Home Improvement

The Basic of the Lacquer Finishes

Nitrocellulose and synthetic lacquers are by far the commonest finishes in industry, because of their fast application and drying. There are brushing varieties, which are thicker and slower-drying for even ‘flowing on’, but generally spraying is best. You can cover large areas in a very short time and, with careful and thorough rubbing down between coats, achieve a superbly smooth finish quite easily.

These materials take between 30 and 60 minutes to dry reasonably hard, and many can be recoated after that time; full curing takes at least a day, and in some cases a week, after which they are among the hardest and most durable of all finishes.

Cellulose is made from nitro-cellulose, resins, plasti-cizers and thinners; pre-catalysed lacquers include cellulose, melamine, and acid hardeners, but the synthetic resin-carrying and acid-catalysed lacquers, the toughest of all, need to be mixed with a hardening catalyst immediately before application.

Cellulose finishes offer no advantages over pre- or acid-catalysed lacquers, apart from a certain extra flexibility allowing movement of the wood. They all come in satin, matt or gloss finishes, and should be used with water-based stains and fillers, or ones that use the same solvents as the lacquers themselves. Like spirit-based products, nitro-stains and fillers are easy to use and mix. If you do use oil- or spirit-based stains and fillers, seal them well with at least two coats of the lacquer you use; and wait and watch for a possible reaction or bleeding through. Avoid laying these lacquers over shellac or varnish.

Lacquers can be tinted with their own colours, or you can use cellulose-based enamels for car touch-up work underneath them.

The hardness of these products, particularly acid-catalysed lacquers, makes them ideal for ordinary household use. They are resistant to mild acids and alkalis and stand up to knocks and heat very well – although damp heat like steam corrupts pre-catalysed lacquers fairly easily.