Shellac – the all-rounder in the gilding workshop.
The insect “Laccifer Lacca” produces the purely natural product shellac by sucking up the sap of host plants and excreting a secretion of dye and resin. This product, known as shellac, is harvested and subject to a purifying process. For application, shellac is soluble in alcohol. Gilders and church restorers often use it to seal surfaces, as a glossy base for oil gilding, or as a topcoat varnish.
When reacting with moisture, shellac forms polymers that are no longer soluble in alcohol. Therefore, it should be stored in a cool, dry place. If shellac flakes get very warm, they can clump together into a lump, also known as blocking. The lump can be broken up with a hammer and the shellac pieces can once again be dissolved in alcohol.
Shellac dissolves in alcohol or spirit. To do this, pour some shellac into a screw-top jar and add alcohol. The alcohol should cover the shellac by about one centimetre. Stir with a stick every 15 minutes until the shellac has completely dissolved. In the meantime, always close the lid so that the alcohol does not evaporate. You can simplify the dissolving process with a nylon stocking: hang the nylon stocking filled with shellac in a drinking glass, and the floating shellac in the solution will dissolve on its own.