[49Stude63]

"Quick-drying solvent-based lacquers that contain nitrocellulose, a resin obtained from the nitration of cotton and other cellulostic materials, were developed in the early 1920s, and extensively used in the automobile industry for 30 years" I think they call the material that is one stage of the chemical reaction "gun cotton" which is explosive but then this material if further reacted creates a lacquer polymer chain. This conversion was totally by accident and in this case that accident didn't go boom!!! If the water is present on the lacquer layer long enough it will seep though the laquer layer and the layer itself will start turning milky. Unlike latex paint that cross-links when it dries so that even if you put water back on dried latex paint if you let it sit a short time and mix it back up you will have water with dried latex paint still in it and not latex paint again. You can take a chunk of dried nitrocellulose laquer and add the solvents back to it and let it sit a short time and mix it and have lacquer again. That is why I called it an open layer since after a while, water, cooking oil vapor, nicotine will eventually over time be absorbed into the lacquer layer which is why most old radios have that dark look to them. Lacquer itself will yellow and darken but the crud it has absorbed over the years adds to this, mostly nicotine from smokers in the past. The newer lacquer resins from the later 40's to early 50's were a result of a safer way to make lacquer and reducing the chance that your paint plant goes boom if you make a minor error.

This link I found covers some of the history and drawbacks of each type of lacquer but all lacquers in the 30's and early 40's were nitrocellulose types. http://www.taunton.com/finewoodworking/M...px?id=2948