Coatings and paint

Most coatings are engineered to perform at a specific total dry film thickness (DFT) that you only reach with the manufacturer's stated number of coats — usually two or more. A single coat typically lands at about half the design thickness, which means weaker protection, uneven sheen and colour, and earlier failure (fading, chalking, peeling). You can't fix it with one thick coat either — over-thick coats sag, trap solvent and cure poorly. Build the film in the specified number of controlled coats. Important: applying fewer coats or the wrong thickness can void the product warranty, so always follow the data sheet's coats and DFT.

Single-pack coatings cure on their own (by air-drying or moisture) — simpler, no mixing, fine for many general jobs. Two-pack (2K) coatings come as a base plus a hardener/activator that you mix in a set ratio; they cure by chemical reaction into a much tougher, more chemical- and abrasion-resistant film — which is why marine, industrial and high-wear floor systems are usually 2K. The trade-offs with 2K: you must mix the exact ratio, you only have a limited pot life once mixed (it'll go off in the pot), and handling and PPE matter more. Match the system to the exposure — and follow the data sheet's ratio, pot life and recoat times.

Start from the product's stated coverage / spread rate (often given as m²/L at the recommended DFT) on the data sheet, then divide your area by that rate — and multiply by the number of coats. Build in extra for losses: porous or rough surfaces soak up more, and spray application wastes more than brush or roller (overspray). Coverage figures are theoretical maximums under ideal conditions, so order a margin over the bare calculation. Many of our coating pages have a built-in coverage calculator to do this for you.

The recoat window is the time range in which you should apply the next coat. There's a minimum (the coat must be dry/cured enough to take the next one, or you trap solvent and get bubbling, sagging or dull patches) and often a maximum (leave it too long and the previous coat cures too hard for the next to chemically bond, so you may have to sand/key it first to get adhesion). It varies hugely by product, temperature and humidity — warm conditions shorten it, cold lengthens it. Stay inside the data sheet's stated recoat window; if you've gone past the maximum, abrade the surface before recoating.