Method for preparing stable bleached shellac

Shellacs have been used as a coating for a variety of substrates for many years. Shellac is typically stored and transported in a dry, solid form under refrigeration. The particulate solid shellac is typically then solubilized in solvent, typically alcohol, prior to use. However, particulate leached shellac is quite reactive. The particulate bleached shellac is not storage stable; it has a short shelf life when exposed to ambient temperature. At ambient temperatures, particulate bleached shellac hardens within days to form a solid block; over time the shellac in the block will also begin to polymerize. If the particulate bleached shellac is exposed to heat during storage or shipping, the polymerization is accelerated. A stable bleached shellac and an improved method for making stable bleached shellac is provided which involves precipitating bleached stable shellac from a pre-shellac solution at a pH of from 5.0 to 6.8, preferably from 5.0 to 6.5, most preferably from 5.0 to 6.0. The stable particulate shellac and the stable shellac solution, have a longer shelf life than conventional shellac. The stable shellac solution is comprised of solubilized particulate shellac in a solvent, most preferably ethanol. The stable particulate shellac and the stable shellac solution have a pH of from 4 up to less than 5 or from 5.0 to 6.8, more preferably from 5.0 to 6.5, even more preferably from 5.0 to 6.3, most preferably from 5.0 to 6.0.