Video transcription from 2009: Lacquer is a general term used to describe clear-coated over natural or stained wood. In this video, we will be explaining the difference between a traditional lacquer and a conversion varnish. To the untrained eye, both finishes look identical. A lacquer is a single-component, pre-catalyzed, nitro-celluloid finishthat has 12-18% solids by volume. It is air-cured. A conversion varnish is a high-end solids, two-part post-catalyzed lacquer, which means a hardener must be mixed with this product for the application. Conversion varnish is 40-60% solids by volume and is chemical-cured. Most lacquers cost $25/gallon. Most conversion varnishes are $60-80/gallon. It takes a greater mechanical aptitude to apply a conversion varnish properly. I’m Charles, and I’m getting ready to spray conversion varnish on this piece of walnut. A conversion varnish has twice the dry film thickness as a lacquer. Conversion varnish is more durable and slightly more elastic than a lacquer. This elasticity is an advantage for wood joint expansion. Conversion Varnish is more expensive than lacquer; the material costs are higher by 30%-50%, which is substantial for larger projects. Conversion Varnish is higher in solids and has a higher buildup and is significantly more durable than lacquer.
Update May 12, 2013 Comments from Industry Colleague and Instructor for the Painters Union, Michael Blevens:
Lacquer shouldn’t be a general term for clear finishes, the only thing they have in common is that they are clear. Lacquers’ are either nitrocellulose, acrylic, or derive from lac. (but those are now called shellac). Some are pre-catalyzed some are post catalyzed, and some don’t use a catalyst ( a more traditional lacquer). A traditional conversion varnish is an alkyd product. Acid catalyzed for curing. It hard to follow along with basic terms like lacquer when you have such a variety of clear
coatings such as: Lacquers- both nitrocellulose, and acrylic Conversion Varnishes- both alkyd and acrylic Acid catalyzed lacquers(mostly acrylic) Waterborne Clear acrylic enamels Waterborne clear catalyzed “lacquers” Waterborne clear cross linked conversion varnishes Don’t even get me started on urethanes