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.