Cellulose Nitrate:
The Resin Made From Wood Fiber
The name nitrocellulose is actually derived from the method of manufacture
of the film forming nitrocellulose resin. Nitrocellulose is produced
by treating cellulose fibers with nitric acid (plus a little sulfuric
acid).
Nitrocellulose lacquers have been manufactured and used as a top coat
system for many years. Their primary usage in the early years, circa
1925, was as an automotive finish. Today, their primary usage is
in production/industrial finishing and cabinet/furniture finishing because
of their fast dry and hard, tough abrasion resistant films. Lacquers
are primarily used on interior wood substrates, but when properly formulated
and pigmented nitrocellulose lacquers also have good exterior durability
on metal.
Most lacquers form a film through evaporation of volatile solvent(s) leaving behind the film former which was dissolved in the solvent(s). This feature enables easy touch-up and re-coat because the touch-up or re-coat actually melts or dissolves the first layer and reforms a smooth even film when dried. By convention, a lacquer is defined as any coating which forms a continuous film through solvent evaporation.
Ease of application is the first feature that comes to mind. Another is fast drying . . . lacquers dry to handle in 60 minutes or less and can be recoated in 1 - 2 hours. They form a smooth, luxurious film capable of high gloss & clarity with excellent touch-up. Nitrocellulose lacquers are self-priming.
Nothing is better than matching the coating to the substrate. In the case of lacquer on wood, the chemical makeup is almost identical . . . i.e. cellulose on cellulose. And, properly formulated to meet National Kitchen Cabinet Association standards, catalyzed lacquers will have outstanding heat & shrink resistance, cold check resistance, chemical resistance (to vinegar, lemon juice, grape juice, tomato catsup, coffee, olive oil, alcohol & mustard) as well as resistance to detergents and water.
What is meant by the term water white?
Water white lacquers impart a clarity unequaled by any other interior wood finishing system. Water white lacquers enhance the appearance of "pickled" or white-washed" wood so popular in today's market. Water white lacquers are designed to resist yellowing over long periods of time. Clear amber lacquers, on the other hand, provide an amber cast that serves to enhance the depth and beauty of the wood finish.
Properly formulated lacquers have earned the United States Department of Agriculture (USDA) acceptance for on site or off site application to structural surfaces where there is a possibility of incidental food contact.
What is the film former in nitrocellulose lacquers?
The film former of nitrocellulose lacquer actually consists of three main types of material: nitrocellulose, resin modifiers and plasticizer. The nitrocellulose resin contributes hardness, toughness, rapid dry and strength. The resin modifier contributes adhesion, film build and additional toughness. The typical blend is 30 - 40% nitrocellulose, 30 - 50% resin and 10 - 20% plasticizer depending on the type of film desired.
Are there unique or strong solvents used in lacquers?
The volatile solvents in nitrocellulose lacquers are divided into three classes. They are: (1) the active solvent(s), (2) latent solvents and (3) diluents. Active solvents such as Acetone and MEK actually dissolve nitrocellulose. Latent solvents, such as alcohols, have dissolving power only when used with active solvents. Diluents for nitrocellulose lacquers are high aromatic content hydrocarbons such as Xylene and Toluene. A typical blend is 30 - 40% ketone, 10 - 20% alcohol and 40 - 60% Xylene and/or Toluene.
