Shellac is the refined form of the natural polymer Lac. . Shellac has many environmentally friendly properties, being a natural, sustainable, renewable and biodegradable product. The Lac resin is a complex mixture of alicyclic and aliphatic acids, mainly Aleuritic, Shellolic and Jalaric acids, but also contains Butolic and Kerrolic acids. Seedlac contains approximately 5% wax and two pigments, the water insoluble Erythrolaccin and the water soluble Laccaic acid.
Shellac has a typical melting point of between 77-90 degrees Celsius. It is a natural bio-adhesive polymer and when heated to between 120-150 degrees Celsius for a sustained period becomes more viscous and rubbery due to polymerisation, leading historians to view it as an early form of natural plastic. Shellac is soluble in ethanol, methanol, propanol, formic acid and solvents of the hydroxyl group.
It also dissolves in aqueous alkaline solutions containing ammonia, sodium borate (borax), sodium carbonate or sodium hydroxide. Seedlac is refined into Shellac using one of three different refining methods, the Melting Process, the Solvent Extraction Process, or the Bleaching Process.
All four forms of Shellac are used across a wide range of industries, although their various properties mean they tend to be favoured for different applications. End-users often prepare Shellac as a solution by mixing it with a solvent such as ethanol or an aqueous alkaline.
