Good day all. After a long break from posting on this site there is some great news to share. Paint Consultant (Pty) Ltd is up and running. Owned by my wife - Joanne - and I, we will be servicing the paint market in the Western Cape, concentrating on the fruit and wine industry's requirements, as well as the domestic housing market.
All advice, backed by nearly 45 year's experience, is given at no cost. The products that we recommend are tried and tested.

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.