Colour choices - performance versus aesthetics

Very often we get requests from customers to tint colours that we know could be problematic. Despite the warnings we give, most times our advice is ignored - often with the predicted consequences. There are two cases that we saw recently, the first involving our paint, and the second involving a competitor's product.
The first case involves product supplied to an entry level housing development in Cape Town. The 'accent colours' specified for the project raised concerns. Blues and greens on the exterior of buildings in a high rainfall area are going to be subject to alkali attack should there be any moisture ingress. Sure enough the original window sill design was cost-driven, allowing moisture ingress. The end result is shown below.

For the remainder of the phases of the project, the window sill design was changed - moisture ingress eliminated and the coatings have survived the first winter without a problem.

The second example of alkali attack we saw this week involves a competitor's product. The house was painted 6 months ago - just before winter. The effects of alkali attack are alarming - indicative of a high degree of moisture ingress.

Hopefully these images will encourage people to check with the manufacturer before colour selection is finalised. Organic colours (bright greens, blues, oranges, reds and yellows) are subject to alkali attack in addition to being less light-fast than oxide shades. They cost a lot more too......

Consequences of incorrect product selection

Some applications, that are less demanding than others, will have minimal consequences if product selection is incorrect. The more technical the application, however, the greater the consequence. A couple of years ago a client was given advice by a paint retail outlet that seemed logical to the advisor, but had disastrous consequences.
The client asked for advice with regard to over-coating a bituminous water-proofing membrane that had been applied to a flat roof below a second storey window. The membrane had weathered considerably, leaving it looking unsightly, and in obvious need of protection from the elements. The client did not want to use Bituminous Aluminium, leaving the sales person in a quandary. We have a product designed for application directly to bituminous membranes (Super Acrylic ST)  but the sales person did not remember that. Logically - according to the sales person - Road Marking Paint is used on bituminous substrates, making it the ideal product to recommend. Unfortunately, bituminous water-proofing membranes become far softer in hot conditions than tar roads do, causing the Road Marking Paint to crack and peel off the surface. Before coating the membrane with the correct product, all of the Road Marking Paint had to be removed from the substrate. This proved to be such a messy operation that it was decided to allow the Road Marking Paint to continue to crack and peel off the substrate on its own - a process that took over a year to complete.
Below is a photo of the roof at a point where most of the Road Marking Paint had peeled of the bituminous membrane. Fortunately it was only visible from the second storey, and that the neighbours were spared the sight!

How to coat swimming pools

As spring has arrived in the Western Cape, and end of year holidays are getting closer, we have the usual increase in requests for information with regard to the coating of swimming pools. This is a far more technical application than most, and it is advisable to get professionals in to do the job. For paint manufacturer's, a sale of generally 10 - 20 litres of paint can result in such dissatisfaction and months of problems that very few companies have swimming pool paints on their ranges. We are the same - we have a product that will work very well if applied by a professional, with due regard to surface preparation and correct application. We are reluctant to give out advice to home-owners or contractors without previous experience in this line.
The short answer then, to the question "how to coat swimming pools", is don't. Get a professional to do the job, pay the price and hopefully have a great summer in your pool!
Not all advice is what home-owner's want to hear - but honesty remains the best policy, even if it sounds a bit abrupt!

Metal Protection at the coast

Last week we were called to give a specification at a coastal installation - literally at the water's edge. Salt spray, wind and high humidity all challenging the integrity of metal gantries and equipment. Design of structures seems not to include the ease of maintaining metal components, and as it often happens we are asked "what now". Good stainless steel would surely have saved the day - but mild steel had been used to construct large moulds for concrete ramps and a series of beams forming an overhead delivery system some 100 metres long, down to the high water mark.
Priming had already been done, after in-house sand-blasting, using two coats of a high build epoxy-ester based anti-corrosive primer. The beams and moulds have to be coated in-situ, limiting application methods, as well as product types. Fortunately, the business has a full-time painter, dedicated to the maintenance of the installation. His days will be filled with removal of dried salt from the metal, sanding, spot priming with the epoxy ester primer and over-coating with Chlorinated Rubber Enamel for the next three years. While this should be music to a paint manufacturer's ears, use of a better material at the outset would have saved a lot costs down the line.

Some weeks are more intersting than others

This week has proved to be far busier and more interesting than most. In the Western Cape, winters are cold and wet, and painting slows down considerably. Spring is in the air now and it seems that business in this industry is set to begin the end of year rush earlier than in previous years.
Buildings visited this week for specifications and advice included an old multi-storey block in the centre of Cape Town (we had to reach the roof of this building through the top floor which proved to be a brothel), a 200 year old manor house in Stellenbosch, an 1800 square metre new luxury home in the farmlands outside Robertson and a fruit pack-shed re-furbishment on a well known estate in Somerset West.
Each of the above sites has its own set of requirements, budgets, and customer expectations. Giving the best advice to each individual owner is our goal, irrespective of the gain to our business. Not all we do as paint technologists is watch paint dry.

What are "snail-trails"

Snail trails can simply be described as shiny vertical run-marks seen on dry paint films. They are often seen soon after water-based paints have been applied, particularly if it has rained or after a heavy dew-fall.
Dry paint films are made up of pigment and binder, but to present the paint in a usable form, many additives are used in the formulation. These additives are mostly water-soluble and remain in the dry paint film until they are effectively washed out by water - be it via rain, dew or by irrigation sprinklers. If the amount of water falling on the surface is low, then only part of the water-solubles are washed out, and they can dry on the surface. This leaves what we call "snail-trails". They tend to be sticky, and can act as a dirt trap as seen in the photo below. Generally these additives are washed out of the paint after the dry film has been wet a couple of times.
Matt paints tend to show snail-trails more readily than sheen paints due to the fact that there is less binder in the dry film. Snail trails can also be seen in kitchens and bath-rooms due to the high humidity. Wiping with a damp cloth often can remove these snail trails.

How to sterilize contaminated surfaces

To support micro-biological growth, moisture, a food source and protection from u.v. light are required. Be it a poorly ventilated bathroom, kitchen, the interior of a wine cellar or fruit pack-shed, these requirements are met, and the growth of fungus and/or algae can be expected. Standard specifications generally call for an initial dose of a fungicide, followed by cleaning to remove the sterilised debris before a second application of the fungicide immediately before re-painting. This specification is sufficient for areas where moderate fungal contamination exists.
Where contamination is high, and where the growth has been present over a long period of time - such as in wine cellars - it is often necessary to repeat the application of fungicide, followed by the cleaning step several times, until all of the growth has been removed. The 'second' dose of fungicide can then be applied and re-coating can commence. These areas should be viewed as 'high-maintenance areas' and these walls should be washed down on a regular basis - as soon as growth re-appears. Installation of u.v. light in these areas will also help to slow down and limit re-growth. The 'one spec fits all' approach cannot be adopted in all cases.
The top-coat applied in these areas should contain a dry-film fungicide to ensure that re-growth is retarded for as long as possible. There is no guaranteed growth-free period, even when all of the above steps have been meticulously followed, as the rate of re-growth is entirely dependant on the conditions in that specific environment. Following the above steps will, however, ensure that you get the maximum benefit for the effort and costs incurred.

Getting prepared for the summer re-paint

With the feeling of spring in the air, it is a good time to start preparing for the summer facelift. Very often people leave painting of homes to the last minute, so that their home looks great for guests over the end of year holiday period. Contractors get booked up with work, and time runs out quicker than one thinks. This could leave you doing a rushed job using an unskilled painter, proving to be disastrous very soon after the fact. Identify what needs to be done now, choose the best contractor you can afford and do some product research so that you are informed when the contractor recommends his product of choice.
Peeling paint can be scraped off walls now, so that the affected areas have dried out completely at the time of recoating. Many times the high-pressure water jetting done by contractors removes paint from these areas, but at the same time forces water into the substrate. If over-coated the day after this has been done, as is the case many times, the coating - particularly if it is a high quality sheen paint - serves only to trap this moisture in the substrate effectively perpetuating the original problem.
Choose the best quality paint you can afford and save for it rather than settle for a cheaper option.
Planning time has begun!

How to remove bore-hole water stains from exterior walls

Often newly painted walls become stained from bore-hole water. The reason for this is that ground water often contains high levels of iron. This dissolved iron leaves brown stains on surfaces when irrigation water evaporates. Many home-owners resign themselves to the fact that they will have to repaint boundary walls on a regular basis to hide these stains. Fortunately this is not the case as we have a water-based degreaser - Tornado - that contains a metal complexing agent (EDTA) that removes these stains when used to wash the surface. The cost of the degreaser is very low, and the added benefit of having very clean, stain free walls after use is very noticeable. Check with your hardware outlet if they have a product containing EDTA for easy iron-stain removal before you repaint.

What happens if paint is applied to a wet surface

Instructions on packaging and in specifications will always call for surfaces to be dry before coating. Recently I saw a perfect example of the results if these instructions are not followed. A contractor had applied a water-proofing acrylic to a newly cast concrete roof, and blistering of the coating occurred in some areas within a week of application. The moisture, still present, in the underlying substrate was prevented from evaporating by the non-porous coating, and pushed the coating off the surface in water-filled blisters. On investigating the problem it was found that the moisture content of the slab was as high as 30%. Ideally, coating should only proceed when moisture levels are 12% or less.
Water-proofing contractors should carry a suitable moisture meter to ensure that the substrate is sufficiently dry before coating. Leaving a rubber mat on the surface over-night is an alternate method of detecting high levels of moisture. A dark patch will be present under the mat when lifted, if there is a high level of moisture in the substrate.
The moral of the story is to check first - rather than to make a costly error.

Apologies for break in transmission

Please excuse the break in postings - have been away for a week at the Kruger National Park. The best coating observed during this time is shown below.

How to coat previously lime-washed walls

A large number of old buildings, particularly in rural areas, have been coated with lime-wash ( also referred to as white-wash). Restoration of these buildings is a complex affair and needs to be undertaken by a skilled contractor who is prepared to pay attention to detail.
The external walls of many of these structures can be anything up to 50cm thick, built without a cavity or damp-proof course. Lime-wash does not seal these walls, so in winter months the walls get very damp, but due to their thickness this moisture never reaches the interior. During summer months the walls dry out, and the lime-wash allows this moisture to permeate though it unchallenged. The paint coatings applied to the exterior of these walls has to be breathable i.e. they should allow moisture vapour to pass through them at a high rate. Matt coatings, with an excess of pigment over binder content, are suitable, and less expensive than the sheen coatings usually used on exterior walls.
Before coating, all lime-wash needs to be removed from the walls. This is best done by scraper and bristle brush as high pressure water-jetting is not an option on old clay brick walls. This is a tedious process, requiring a lot of patience and perseverance. Once all the lime-wash has been removed, and the inevitable repairs to the plaster have been completed and dried, apply one coat of an alkali resistant Plaster Primer and allow to dry overnight. This primed surface can then be top-coated with an interior-exterior matt finish paint such as MattCoat 40.

What are 'high-traffic' coatings

Work-space floors can have very different requirements due to the activity that takes place in that particular area
From high people-traffic in school or office block passageways, to heavy vehicle load-bays or work-shop floors - each area has its own set of challenges. Substrates can vary from wood, to galvanised iron through to screeded concrete, and it is essential to take these factors into account when selecting a suitable coating.
When it comes to coatings (as opposed to self-levelling screeds), twin pack epoxies tend to be the product of choice. They are self-priming on cured cement (due to their chemical resistant properties) and can be applied directly to bright metal - although priming with a twin-pack etch primer would give better long term results.
On wooden floors - where high traffic is expected - it would be better to use a twin-pack polyurethane. They are, in general, more flexible and do not yellow over time so that the natural appearance of the wood is not affected.
Passageways, depending on the volume of traffic, the substrate, and in the case of schools - the budget, can be coated with twin-pack epoxies (best option) or single pack polyurethane enamels. The single pack polyurethane enamel, although not as abrasion resistant as the epoxies, is far cheaper and can be applied by less skilled applicators.

How to identify the type of coating currently on a surface

When selecting the coating type to apply to a previously painted surface it is important to know whether incompatibility could result. The best way to avoid this is to first identify the coating type currently on the surface. Quick tests can narrow the options down to a level where a potentially expensive compatibility problem is avoided.
Without becoming too technical, dry coatings exhibit solubility, or a lack thereof in certain solvents, and this can be used to identify the coating type on the surface.
The method used is to rub the surface of the coating with a rag wet by solvents 15 times back and forth (known as 15 double rubs), and inspecting the rag for dissolved paint.
If 15 double rubs using Lacquer Thinners as the solvent caused no dissolution of the paint coating, then the product on the surface would be a twin pack epoxy or polyurethane.
Similarly, if a high aromatic solvent dissolves the coating, a water-based coating is indicated.
If the high aromatic solvent does not dissolve the coating, but Lacquer Thinners does, then a single pack solvent based product is likely to be on the surface.
Although this is not a fool proof method of testing a paint film, it does give a good idea of what one is faced with, and helps when selecting a new top-coat option. Costly mistakes are avoided when the correct information is at hand when specifying coating systems to be applied to previously painted surfaces.

Honest advice vs making a sale

A conflict arises when visiting a site between making a sale and giving the customer the best advice possible. We like to solve coating problems, and if the problem can be solved by using a product on our range, then a sale is possible. It is better to walk away from a sale than to offer a solution that is not guaranteed - your own personal integrity, as well as the technical integrity of your products remains intact. For a technical person this is probably easier than for a salesperson driven by commission, or sales targets, but we pride ourselves on the fact that we do not fall into that trap. This is why we have technical consultants rather than sales-people. Many a time have we advised customers to tile rather than paint, to go for cheaper options in certain applications, or simply questioned the reason for wanting to paint in the first place. Paint cant solve all issues, and the customer needs to be told when this is the case, so that more cost-effective alternatives can be looked at. In the same way, customer expectations of coating systems need to be managed - by giving accurate information with regard to life-expectancy of the coating - so that later disappointments are avoided.

Importance of identifying the needs of the substrate

In many cases we have been to sites and viewed substrates that have different requirements for different areas of the same substrate. A factory floor often will have high and low traffic areas in the same work-space. Wine-cellar walls often have wet areas where lower sections of walls need more specialised coatings than the remainder of the wall. Exterior walls often have exposed plaster or brickwork below the damp proof course that need a different coating than the upper walls.
It is important for a contractor or specifier to identify these requirements before coating work commences, so that the correct combination of products can be used. This saves a lot of money in the long term and keeps the coated structure looking its best for the longest period of time possible.

Solvent Sealer

Solvent Sealer is a clear, solvent based pure-acrylic penetrating coating. It was originally formulated to seal coloured floor screeds, but has since its launch found many other areas of application. Being a pure acrylic, it is non yellowing, making it an ideal choice to seal interior or exterior cementitious substrates. Flower pots, planters, face brick walls and paving, concrete walk-ways and stoeps have all been successfully sealed by this product. It is a low viscosity product that penetrates and binds the substrate, with little film build-up on the surface, so that the character of the surface is minimally affected. The product is xylene-based resulting is a very quick drying time. The abrasion resistance is appreciably lower than that of twin-pack coatings so only low-traffic areas should be sealed with this product.

"Food-grade" paint

We get a regular stream of calls asking for food-grade paint for coating interior walls and equipment in food processing areas. The short answer to the question put to us is that there is no such thing. Additives such as colourants, preservatives and flavourants that are used in processed food and beverage production are sold as food-grade as they are consumed. Paint, on the other hand, will hopefully not be consumed. Dry paint films are, in the main, non-toxic and are safe when it comes to contact with food. Over the years many of the known toxic raw materials used in paint production have been banned and replaced with safe alternatives. Low VOC (volatile organic compounds - basically solvents) coatings are available to be used when called for, further reducing the chances of consumables being tainted during production. A range of FDA approved biocides has been offered to us for use in products destined for use in food or beverage processing plants - the use of products will contribute further to the safety of the coating supplied. Good planning of maintenance during plant shut-down periods will ensure that no contamination of consumables occurs during the application phase, and that a fully cured and thus food-contact safe coating protects and decorates the interior of your food or beverage processing plant.

Previously coated wine tanks

Many of the older wine cellars still have steel wine tanks in use. These tanks are typically decades old, and often have been coated on the exterior with many layers of a variety of coating types. On number of occasions we have been called in to advise on the route forward with regard to the rehabilitation of such tanks. After sterilizing and cleaning the tanks - Fungal Wash followed by Tornado Degreaser - it is possible to get a good look at what is being dealt with. Now rust can be removed and treated, before selecting a suitable top-coat. We have, in many instances, gone the route of recommending Druiwebakverf (Fruit-bin paint) - a quick-drying solvent based acrylic/chlor-rubber bound coating incorporating an anti-corrosive pigment. The acid resistance of the coating is a big advantage, and the cost relative to twin-pack materials is favourable. It can be applied to substrates where alkyd based coatings were previously used, which is often the case.

Cleaning and sterilizing of wine tanks

Maintenance of cellar hygiene plays an important part of over-all cellar maintenance. We advocate a pro-active approach to the control of fungal growth, rather than waiting for the inevitable unsightly appearance of contamination before treatment is considered. This applies equally to coated surfaces as well as stainless steel tanks. Regular sterilization and cleaning of tanks ensures that they remain in a bight and shiny condition. After the application of Fungal Wash to the contaminated surfaces, the tanks can we washed down - either by high pressure water-jetting, or by manual scrubbing - using Tornado Degreaser. This is a very simple and inexpensive treatment that will keep one of the components of the cellar in great shape.

These are examples of well maintained tanks from different cellars in the Western Cape. Some of the tanks we see are very badly contaminated, and the "before photographs" would be quite alarming.

Densification of cement plasters

Cement floor screeds or wall plasters can be densified by application of a solution of sodium silicate.
Sodium silicate is a liquid glass, that, simply put, bonds to the cement/sand matrix and reduces the spaces between particles in the matrix. This results in the hardening of the upper layer of the plaster, as well as reducing the porosity without fully sealing the surface. It is inexpensive, non-toxic, odourless and very easy to apply. This makes it an ideal option in certain applications, particularly where legislation does not call for the substrate to be sealed. There is no need to wait for the product to dry before walking over the applied area, as no film is forming on the surface. Lithium silicate is a slightly more costly variant, said to have better properties with regard to hardening.

Crack repair - Weathercrete and Joint Sealer

I have, in separate posts, dealt with the repair of cracks using both Weathercrete and Joint Sealer.
Weathercrete is a "twin-pack" material comprising of a pre-weighed, dry cement component, mixed immediately prior to use with a liquid polymer. The resulting repair plaster has very good adhesion to a variety of substrates, is water-proof, highly abrasion resistant, and has a good degree of flexibility. Thorough mixing on site prior to use is a problem in some cases, as mechanical stirring is advised. More and more of our regular contractors are opting to use Joint Sealer - a high volume solids acrylic, rather than Weathercrete, to fill cracks on walls. Weathercrete remains the product of choice for repairs on floors, however, where abrasion resistance needs to match that of the surrounding substrate.
On walls, both repair materials should be over-coated with two coats Elastocryl prior to the application of top-coats, so that the necessary film thickness is achieved to permanently seal the crack.

Single and Twin Pack Etch Primers

The priming of non-ferrous metals became an issue during World War 2 when aircraft and ships were starting to be built using aluminium rather than the heavier steel previously used. The U.S. military claim the original development of etch primers and their introduction into the coating industry. Phosphoric acid, when added to paints based on phenolic/polyvinyl butyral resins provide the adhesion required to successfully coat 'difficult' metals. Anti-corrosive pigments such as zinc tetroxy chromate were used to provide the protection against corrosion.
After the withdrawal of calcium plumbate, and chromate pigments from the market due to health risks attached to their use, etch primers have been more and more popular, not only for priming non-ferrous metals, but as the first choice in primer for ferrous and galvanised metals as well. The solvent blend used is rich in alcohols, making the coating quick drying. The product can be applied by spray  as well as by brush or roller.
As a rule, in the South African coating market, single pack etch primers are applied to galvanised iron or ferrous metals, and twin pack etch primers are applied to non-ferrous metals (mostly aluminium or stainless steel), usually by spray application. Twin pack etch primers have, in addition to this, been very successfully used to prime glass-fibre substrates for subsequent coating.

Dealing with crazy-cracking

Under certain conditions, new cement plaster hardens with a hexagonal pattern of very fine cracks present, roughly the size of an adult's hand. These are not visible to the eye, but if a solvent based bonding liquid is applied to the surface, their presence is shown very distinctly. As things stand there is no special coating requirement, and the usual one coat of a Masonry Primer and two coats of a good top-coat will suffice. A big problem, however, arises when these cracks open and close under large temperature changes or settlement of the new structure.
The very standard coating procedure given above will provide up to 100 microns of top-coat. When these cracks open - often as much as 500 microns, huge stress is applied to the dry paint film above the crack. Upon stretching to accommodate the crack below, the paint film above it becomes thinner, much like a rubber band would if stretched. For a paint film to accommodate that type of stress, not only does it need to have an intrinsic degree of flexibility, but there also needs to be enough film thickness to allow that type of elongation without the film breaking above the crack.
The leading  international Pure Acrylic binder manufacturer conducted a series of tests to determine the film thickness required to successfully bridge opening cracks of this nature. Not surprisingly, the binder had to be of a highly flexible nature - but what was surprising was the fact that a minimum film thickness of 320 microns was required to survive the ordeal. This would require around 7 coats of most top-of-the-range pure acrylic exterior coatings currently used in the South African paint market. I have never seen a specification calling for 1 coat Masonry Primer and 7 coats pure acrylic top-coat before!
Should you need to re-coat a wall where crazy cracking is evident, after surface preparation, apply one coat Plaster Primer, followed by two coats Elastocryl ( a fibre re-enforced, high solids, pure acrylic coating) at 5 square metres per litre before coating with two coats of the chosen top-coat. Better still, contact us for advice specific to your job's requirements.

Repairing of plaster cracks - Weathercrete.

As part of surface preparation, when repainting plastered surfaces, cracks are often an issue. Hairline cracks can be sanded to a smooth profile, spot primed with Plaster Primer then over-coated with two coats Elastocryl prior to recoating the wall. The two coats Elastocryl will give 210 microns of film thickness, before the top coats are applied. The total film thickness over the crack will then be sufficient that should the crack re-open due to movement of the substrate, the paint film above it will not break.
Larger cracks should be raked or angle ground open, to a sound substrate, before re-filling. Here we recommend the use of Weathercrete -  pre-weighed cement to be mixed with the polymer supplied, to be used as the fill compound. The resulting profile of the dry fill will match the surrounding plasterwork to a far greater degree than when using cellulosic fillers. Patting the surface of the still wet filled area with a damp sponge helps to match the surrounding plaster profile. Once this is dry, spot prime the repair with Plaster Primer, over-coat the repair with two coats Elastocryl and proceed with the application of top-coats.
Weathercrete can be used to fill plaster defects on cement floors, as a waterproof grout between tiles, or even as a tile adhesive. Be sure to clean the equipment used with water directly after use, as once dry, the adhesion to metal is so good that you may have to angle-grind it off.

Twin Pack Epoxy and Polyurethane coatings

Twin Pack Epoxy and Polyurethanes are extensively used in industrial applications. Most of the volumes sold of these two products are used for flooring or coating of machinery.
Twin Pack Epoxies, in general, have better solvent and chemical resistance than the Twin Pack Polyurethanes. They have better adhesion to metals, and again, in general, have better abrasion resistance than Twin Pack Polyurethanes. They are also cheaper than their Polyurethane counterparts. Their chief draw-back when compared to TP Polyurethanes is their very poor u.v. resistance - making them suitable only for interior coating applications.
Twin Pack Polyurethanes can be used for demanding out-door applications such as the coating of boats, trailers, automotive coatings, aircraft, trains etc.
Both options have similar surface preparation and curing requirements, and both require a level of expertise to use. Always check with the supplier before using these products as to their suitability for your requirements, and obtain a detailed specification for the application. When used correctly, both products can provide many years of protection.


Fruit packaging warehouse floor - Twin Pack Epoxy

Workshop floor - Twin Pack Epoxy



Wood-floating of cement floors

Very often we are called out to give advice on the coating of cement floors. The proud new owner of the building shows us the power- floated floor. Many times the floor is as smooth and shiny as a mirror. Unfortunately this is not ideal for coating, as the surface has been rendered totally impervious to coating penetration. The first step required in term of surface preparation is then to roughen the surface so that it resembles 100 grit sand-paper. This will ensure good adhesion and penetration into the substrate, and prevent the coating delaminating from the substrate. Impact of a heavy object falling onto the coated surface, or a vehicle - even a pallet-jack – turning sharply, can cause the coating to come away from a very smooth surface if no penetration has been possible. The best method of roughening a smooth surface is by floor grinder. These can be hired by the hour from construction equipment hiring businesses. They create a lot of dust, but do the job very well. It is best to vacuum up the dust using an industrial vacuum after this process is complete. Ensure that the entire floor, including edges right up to the walls and hollow spots, are evenly abraded.

An alternative method is to acid etch the floor, but the drawbacks far outweigh the reduced cost of this approach. Strong acids are hazardous chemicals and should never handled without the correct training and Personal Protective Equipment. Acid fumes generated are highly corrosive – both to the applicators and to electrical distribution boards. The acid tends to lie in hollows on the surface, leaving high spots untreated. The floor needs to be rinsed off after etching – leaving it wet and therefore unsuitable for immediate coating. We do not sell acids used for this application due to these limitations.

 

Below is a photo of a floor topping being wood trowelled for later coating.

 

The moral of the story is that if you are screeding a floor that will be coated at a later stage, save yourself some money and have it wood-floated to a rough finish.

Coating of polystyrene ceiling panels

More and more ceilings boards and cornices being installed these days are made out of polystyrene. They are light-weight and easy to mould into fairly intricate cornice designs. Not only are new ceilings boards often made of polystyrene, but there are a large amount of industrial buildings where thick (75mm) panels were used to form dropped ceilings - both for insulation and sound dampening considerations. Some of the older ceilings we have seen in wine cellars have been so contaminated with fungal growth that we have advised the client to replace them rather than trying to sterilize and coat them. Coating of these panels - after sterilizing with Fungal Wash, if required, is a simple process. Ensure that the product to be used is water-based and you can simply apply two coats by conventional means. Any aromatic solvent containing paint cannot be used, as the polystyrene will dissolve.

Elastocryl - quick drying waterproofing system

Elastocryl was developed at the request of local waterproofing contractors to provide a product that can be used throughout the year - including wet and cold winters. After doing our research into what was being used elsewhere in the world, with similar climates to the Western Cape, we had a starting point to work from. Laboratory produced samples were tested by contractors, fine tuned after feed-back, and we were up and running.
The success rate of this product has been phenomenal - we receive many calls from satisfied customers telling us how Elastocryl worked where many attempts with other products have failed. Essentially it is a high Volume Solids adhesion promoted pure acrylic, re-enforced with a high loading of wood-fibre. It dries a lot faster than other water-based waterproofing coatings, and can be applied with rain only hours away.
Possibly the best testimonial we have received was from the owner of a dedicated paint outlet - one of our opposition - who successfully waterproofed their own shop roof during light drizzle. Their own product had failed - even though it was applied in good weather conditions. Needless to say they now sell Elastocryl very successfully in their area, even though it is produced by an opposition manufacturer.
Elastocryl can be used with or without a polyester membrane, depending on the application. Application of two coats of Elastocryl at 5 square metres per litre to badly hairline-cracked substrates, followed by the top-coats, has rendered many buildings free of moisture ingress. Sealing of parapets, 'flat' concrete roofs, even reservoirs and ponds, have all been successfully achieved by this product.

Give us a call before your next waterproofing challenge - Elastocryl will beat it!

Druiwebak Verf - literally Grape-bin Paint

This is a versatile product made to coat metal bins that harvested grapes and fruit are transported in.
It is a quick drying solvent based coating, resistant to acid and alkali, self priming on metal and has low moisture and oxygen permeability. That is quite a list of attributes for a single product, and is what makes it so versatile. Low moisture and oxygen permeability reduce the chances of the substrate rusting and together with the inclusion of an anti-corrosion pigment, make the product a good choice as a metal coating. Resistance to acids, self priming on metals, low oxygen and moisture permeability, and good u.v. resistance makes it ideal for the primary use on grape/fruit bins. The fact that it is alkali resistant makes it suitable for coating directly onto cement plastered surfaces. Walls and floors in wine cellars and fruit pack-stores have been successfully coated with this product. The binder composition is similar to that of the traditional road-marking paint - the ones that lasted years but are now deemed to be too expensive.
The photo below is that of a wall in a wine-cellar, subsequently coated with Druiwebak Verf, after sterilizing with Fungal Wash.

Druiwebak Verf has Thales approval for use in wine-cellars.

Primers and undercoats

Primers, be they metal or wood primers, are formulated to be in direct contact with the raw substrate. When preparing a surface for repainting, one of the requirements is to scrape off loose or flaking paint . When the prep work is complete, and the substrate has been exposed in discrete areas, that particular area needs to be spot primed with the appropriate primer before recoating. Many times we see metal primers being used over the entire surface of previously painted metal or wood objects, before the object is repainted. Anti-corrosive pigments, used in metal primers, need to be in contact with the metal substrate for them to be effective. Similarly, oils in wood primers need to be in contact with wood for them to lubricate wood fibres.
Plaster or Masonry Primers are alkali resistant, breathable coatings designed to penetrate and bind the upper layer of a plastered substrate. Often we see contractors using "Universal Undercoat" in place of Plaster or Masonry Primers, often with disastrous consequences. Universal Undercoat's are not alkali resistant, and should only be used over primed surfaces. They contain neither anti-corrosive pigments, nor wood-fibre lubricating oils, making them unsuitable for use directly onto metal or wood.

Coatings for Mass Housing

Mass housing development is huge in South Africa, and most other African countries. In the Western Cape, all exterior coatings have to carry an Agrement Certificate. This ensures that the product will effectively seal and protect the structure, and have an acceptable life expectancy. We have been supplying coatings for mass housing for may years, and have formed good relationships with our clients. By getting involved in identifying potential design problems we have been able to eliminate many water-proofing and coating issues, thus saving the client both time and money. Joint Sealer (see previous post) was developed specifically to deal with a problem on a large mass housing development, at the request of the client. The notion that cheaper housing will use cheaper coatings is false - in many ways the coating requirements are more demanding than those used in the 'conventional' housing market. Taking a hands on approach to technical service on mass housing sites has taught us a lot about practical building methods, and has put us in a position to provide coating solutions to diverse application challenges. The two photos below give an indication of the scale of the projects. Both of these projects involved supplying the coating requirements for over 2000 units.

Weatherklad - Heavy duty exterior protection.

Weatherprufe Weatherklad is our flag-ship product. It is an adhesion promoted pure acrylic, formulated with high volume solids for thick film protection. The product is fibre re-enforced for crack bridging and tensile strength, and contains a dry film fungicide for protection against mould and algal growth. Many projects, from sea-side homes and apartments to farmsteads in the hot Western Cape interior, have been successfully coated with this product. We produce the coating in a range of colours for exterior walls, or tinted to the colour of your choice,  as well as in oxide shades for use as a roof paint. A variant of this product, Cellarklad, containing the maximum recommended level of fungicide has Thales approval for use in wine-cellars. Below is a photograph of a recently completed project in Cape Town, where Weatherklad was used as the exterior top-coat.

Polarsheen - Low temperature curing acrylic

Polarsheen is a pure acrylic water-based paint formulated to dry at very low temperatures. It has Thales approval for use in wine-cellars. It has been successfully used, over a period of several years, in Controlled Atmosphere Rooms (low temperature and reduced oxygen storage rooms where fruit is stored) across the Western Cape. The product has low odour and is able to dry at temperatures below 4 degrees Celsius. Flexibility is very good resulting in the product being used to seal the gaps between panels in Controlled Atmosphere Rooms. The photograph below was taken in an underground wine cellar coated with Polarsheen. The product also contains a dry-film fungicide, to prevent mould growth.

Wood varnishes and wood seals

Protection of exterior wood can cause a lot of head-aches if the right route isn't followed from the outset. Often the quality of wood used in South Africa is not the best, and this only adds to the problem. If new work is being done, start off by using the best timber you can afford. Hard, dense woods are more dimensionally stable than softer woods, and the additional cost is money well spent.  Harder woods are less porous than soft woods, meaning there is less swelling due to water ingress, and ultimately less chance of rotting. They are also less prone to warping due to heat - both of these factors lead to less stress being placed on the coating, from factors other than uv light and the elements. Having installed the timber, check with the timber supplier whether the density is suitable to be coated with a varnish, or a wood-seal, as very dense timbers should only, at the most, be protected by a wood-seal.
Preparation of new timber involves sanding the surfaces to be coated to a smooth finish and removing dust. Knots (if present) should be sealed using a knot-sealer as per the manufacturer's instructions.

• Varnishes are typically solutions of long oil-length alkyds (a solvent based binder type) containing a low level of Linseed Oil ( to lubricate the upper-most wood fibres). Other additives could include u.v. absorbers and transparent iron oxide colourants. Typically this finish is glossy. The coating will have a limited penetration into the timber - so thinning the first coat up to 10% with Mineral Turps is advised. Allow this to dry for 24 hours, and thereafter apply the first of two top-coats (unthinned) with 24 hours between coats. Maintenance of these coatings would involve sanding the coated timber to an even, matt finish, and re-applying one unthinned coat every 12-18 months.
• Wood-Seals are dilute solutions of long oil-length alkyd, with a higher level of Linseed Oil, and waxes. The same additives are used as for the varnishes. There is generally more penetration of a wood-seal into the timber than varnishes, and the product has a matt, waxy appearance. They take longer to dry - due to the higher Linseed Oil level, and for this reason are seldom used indoors. Three coats can be applied (at 24 hr intervals) to the prepared timber. Maintenance of these coatings involves cleaning the surface with a rag soaked in Lacquer Thinners, allowing to dry, and recoating. Maintenance intervals are the same for each coating type.

Twin Pack Epoxy Coatings

It has become very fashionable over the last few years to have coated cement floors in office entrance halls as well as in kitchens and bathrooms in domestic homes. These floors are often coated with Twin Pack Epoxies. A problem can arise when the interior design calls for colours produced from blends of different pigment types. Epoxy resins are ideal for the production of industrial coatings, where performance is more critical than aesthetic attributes. Pigments are not well stabilized in such resins, and preventing different types of pigments from floating is a problem associated with these coatings. I saw a problem created by the floating of pigments during roller application to a floor that can be directly attributed to the tinting of a medium grey shade to a blue-grey colour. Due to different pressure applied by the applicator, roller width stripes of noticeably different colours were evident in some areas. Murphy's law reigned supreme in this case, and the darker stripes were in the middle of the floor. A third coat, carefully applied, sorted the issue out. Fortunately, this was a small area that had been coated, and the applicator had enough product left over to complete the repair coat.

Tornado Degreaser

Tornado Degreaser is a water-based highly concentrated multi-purposed product that has had a lot of success in diverse applications. It has approval for use in wine-cellars (via Thales Institute) and cleans the exterior of old wine tanks back to bright metal. Diluting the product anywhere up to 20:1 with water allows it to be used as a household tile cleaner, wall cleaner, pre-soak for oily clothes (reportedly even bloody clothes after a hunting trip), pot cleaner amongst others.
More paint related uses include degreasing of new galvanized iron roof sheets, removal of oil patches from workshop floors and degreasing of metal objects prior to coating. The water-based formulation makes the product safe and easy to use and results are excellent.
Copper stains in old enamel baths and iron stains on boundary walls from bore-hole water are no match for the product either.

Painting of boundary walls

Correct procedure for this application will ensure maximum life span of the coating. Very seldom are boundary walls constructed with the inclusion of Damp-Proof Course (DPC). This means that the lower part of the wall will be subject to rising damp. Watering of lawns and flower beds adjacent to the walls provides a constant source of water around the base of the wall causing this to be a constant issue. Here's how to deal with this in the best possible manner.
Remove all loose and flaking paint by scraper. Cracks, if present, should be opened up by angle grinder. Refill these areas using a 3:1 sand/cement mix using Weatherbond Enhance (a water-proofing polymer) to wet the mixture to application consistency. Using a sponge, remove excess and match the appearance of the repair plaster to the existing profile surrounding the repair. Allow this repair to dry for 24 hours. Spot prime repairs or any exposed raw plaster Using Plaster Primer and allow to dry for 8 hours. Treat any fungal/algal contamination by application of Fungal Wash - allow 6 hours for the product to sterilise the surface and then scrub or high pressure jet the debris of the wall. Re-apply Fungal Wash and leave to dry on the surface - do not wash this off before re-painting.

Water-proof the top horizontal surface, or coping, by application of two coats Elastocryl, at a spread rate not exceeding 5 square metres per litre, allowing two hours drying time between coats. This area can then be coated with two coats Weatherklad in approved colour ( 8 square metres per litre, 4 hours drying time between coats). This will eliminate the possibility of water-ingress from the top of the wall, leaving only the issue of the rising damp to be best accommodated.
The vertical surface should be coated with two coats MattCoat 40 - a breathable matt finish product.
This will ensure moisture rising in the wall has the greatest possibility of diffusing through the coating, in the form of water-vapour, without damaging the coating. MattCoat 40 is also a far cheaper product than sheen finish alternatives - it is not often that the best technical option also costs less!!

Paint store audit and advice

Maintenance Managers on wine farms, fruit farms, and in the fruit packaging industry (as well as food and beverage suppliers) are tasked with maintaining the standards required for regular audits and inspections related to accreditation for supply to the local or international markets. Budgets for the required maintenance are often limited and the need to get the full benefit out of money spent is obvious. In many cases we have seen paint stores containing several half used paint cans, often produced by several different manufacturers, lying idle and collecting dust. Putting these products to use before re-ordering could save a lot of money.

A service we offer is to check the viability of the products currently stocked in terms of stability and suitability for use. This involves the identification, determination of viability, re-labelling if necessary, re-sealing and recommendations in terms of areas that can be coated with the product concerned. This results in substantial savings and leaves you with easily identifiable products – and a tidy store, at no cost to you.

Water-based masonry primers

Water-based primers have been gaining popularity for some time now- not only for environmental concerns, but also as a cost consideration. The cost consideration is unfortunate, but a real issue in the market we service. One disadvantage that a water-based primer has compared to a solvent-based masonry primer is the limited penetration into the substrate. Water-based binders are emulsified, and the droplets have a measurable particle size, meaning that penetration is not possible into interstitial spaces smaller than the droplet size. As long as the substrate is well bound,dry and not friable, water-based primers perform well. An experienced contractor will be able to make the call as to whether the substrate is suitable to be primed with a water-based primer or not, whereas decisions that are solely price driven can result in unnecessary failures. Recently I saw an instance where a still wet plaster-skim had been primed with a water-based primer and over-coated with a washable sheen acrylic, with predictably disastrous consequences. The entire coating system could be fairly effortlessly (fortunately) peeled off the substrate. The back of the paint film was entirely covered with loosely bound skim-plaster, and the moisture level was measured between 19 and 22%. The moral of the story is to apply all masonry primers only to dry substrates, but water-based primers especially only to dry and non-friable substrates.

Wet and dry film thickness

From the previous two posts, we saw how to calculate wet film thickness from the recommended spread rate. The relationship between wet film thickness and dry film thickness is dependant on a formulation parameter known as Volume Solids. This value, given as a percentage, is usually found on the Technical Data Sheet of the product. A Volume Solids of 40% means that when the paint dries
40% remains on the surface forming the dry paint film. So if the wet paint film thickness was 125 microns and the Volume Solids of the paint applied was 40%, then the dry film thickness will be 50 microns (125 x 40/100).
Two coats, applied at 8 square metres per litre, of a paint formulated at 40% Volume Solids, gives a dry film thickness of 100 microns.
Applying a product at the manufacturer's recommended spread rate ensures that the correct dry film thickness results and the performance of the coating is maximised. Thinning the coating by addition of water or solvent, or spreading the coating too far, only results in a thinner dry film - and the life expectancy of the system is reduced.

More on Spread Rates and Film Thickness

The relationship between spread rate - given in square metres per litre - and wet film thickness is fixed. Applying paint at a spread rate of 10 square metres per litre gives a wet film thickness of 100 microns. This obviously assumes that the paint is evenly applied to a smooth surface. To calculate the wet film thickness from the spread rate simply divide 1000 by the spread rate. So a spread rate of 8 square metres per litre gives a wet film thickness of 125 microns.
When paint dries, water or solvent (depending on whether the paint applied is water-based or solvent-based) evaporates leaving a dry paint film. The relationship between wet film thickness and dry film thickness is not fixed and will be dealt with in the next post.

Spread rate and film thickness

Manufacturer's will recommend that products are applied at a specific spread rate. This is literally the area covered by one coat per litre of paint. This information is given on the Technical Data Sheet of that particular product. Applying the paint at the recommended spread rate ensures that the paint dries to an acceptable film thickness. Applying the correct amount of coats of paint then gives the correct film thickness of the system. This dry paint film protects the surface coated and will live up to the life expectancy as long as no deviation from these recommendations have been made. Two coats of a good exterior coating, applied at the correct spread rate, will provide a paint film thickness about 100 microns. This is only one tenth of a millimetre - and much is expected of it. Given that acrylics weather naturally at a rate of around 8 microns per year when exposed to u.v. light and the elements, it doesn't make much sense to skimp. Using a skilled painting contractor, familiar with the product to be used, will ensure that the product you have paid for lasts as long as you had expected it to and saves you a lot of money in the long term.

The PVA confusion

The term "PVA" is often still used to describe a water-based paint. This goes back to the post second world-war era when it was the first binder type to be used in the production of water-based coatings. It had many shortcomings as a binder and was soon super-ceded by Pure Acrylics and Modified Acrylic binders, now still used as the main binders used in water-based coatings. Ask your paint manufacturer or stockist for the binder type used in the product you are about to purchase, especially if you see the term "PVA" used in the product name. A simple rule of thumb is that Modified Acrylic binders are used to produce matt or textured finish paints while Pure Acrylic binders are used to produce sheen and roof paints.

Galvanized iron roof sheets

New galvanized iron roof sheets are best left to weather for a full year before coating. This, however, is not always possible in practice. Should the roof sheets need to be coated within this time period, or if a water-proofing system is to be applied over a portion of the area, it is essential to first thoroughly degrease the area to be coated. This removes the residual oily layer present on the new roof sheets when supplied. There are many products available that will successfully accomplish this - we have an eco-friendly water-based product called Tornado Degreaser on our range that is ideal for this application. This will ensure the good adhesion to the substrate of the coating to be applied.

Wine Cellars - Specification file for all buidings

One of the services we offer to wine cellars is the compilation of a file of specifications for the re-coating of all buildings on the estate. This gives the Maintenance Manager all of the surface preparation and coating instructions,  product requirements and quantities for all of the buildings from the main homestead, managers house, labourer's cottages through to the cellars. This can be used any time in the future for maintenance budgeting and planning. This is done free of charge and with no obligation.

Wine and fruit industry coatings

Now that the harvest time is over, maintenance starts on wine cellars and in fruit packaging warehouses. We have an impressive portfolio of customers in these industries and offer a full package of advice, training and products approved for use. Large amounts of money can be saved by good planning and routine coating maintenance. We service the entire Western Cape and have references from top clients. As an additional service we keep full records of all products used for HACCP, GLOBAL GAP and ISO inspections. We are listed as a supplier in the Wineland Directory 2014 edition due to go into circulation 1 July.

Joint Sealer

This product was developed during 2013 at the request of a mass housing developer constructing panelled houses in the Western Cape. It is used to seal the joint between panels, and the main requirements are good adhesion to the substrate, flexibility and high film build. Essentially, it is a high solids acrylic formulated on a blend of binders to provide the required properties. As with all products of this type, there is a degree of shrinkage on drying, necessitating two "coats" to be spackled into the joint. Since the successful introduction of the product, contractors have used it to fill plaster cracks with equally good results. Its toughness and flexibility would make it a good option to seal between timber panels used to construct timber homes, in addition to the above applications.

Coating of cement floors

After inspecting a floor for an applicator to determine its suitability for coating, I feel that putting down a couple of essential pointers would be appropriate. Previously uncoated cement screed floors need to be fully cured, dry, free of oil or dirt, and of a sufficiently rough profile before coating. Often calls come in from applicators or home owners after the coating has been applied asking why problems have occurred - all of which could have been prevented had these guidelines been followed.  Cement slab driveways and verandas (stoeps) are often thrown without a damp proof course below them - here the rule is simple - do not coat them.
Allow at least 28 days for the cement topping to cure, then check the moisture level with an appropriate moisture meter. The moisture level should ideally be below 12% as measured by  a Protimeter. Ensure that the profile of the surface resembles 100 grit sand-paper, if not mechanically abrade the floor using a floor grinder. This step will often remove surface dirt and oil at the same time. All dust should then be removed by sweeping or vacuuming the surface clean.
The first coat can now be applied - preferably thinned 10% by addition of the relevant solvent. Generally, a 24 hour drying time should be allowed before application of the first unthinned top-coat. After another 24 hours, the second top-coat can be applied. Depending on the coating type, there will be a specific time that needs to be allowed before the coating is subjected to heavy traffic.
Coating types vary from Water-based Acrylics to single pack Alkyd and Polyurethane-Alkyd enamels, then on to the Twin Pack Epoxy and Polyurethanes. There are cost and performance advantages related to each of the above options - check with your supplier as to which one best suits your requirements.

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