Under the solvent process, practically wax and impurities are completely removed by dissolving the seedlac in a suitable solvent, usually, chilled industrial alcohol. The solution is then filtered through fine cloth and the alcohol is recovered by boiling the solution. The molten shellac is then stretched to the required thickness on a roller. The product does obtain is known as Dewaxed Shellac. Highly sophisticated grades of dewaxed and decolourised Shellac can be produced by this method by adding activated carbon as the decolouring agent. The impurity is around 0.2%.
Dewaxed Shellac
Grades of Dewaxed Shellac :-
a. Dewaxed Orange
b. Dewaxed Lemon
| Dewaxed Orange Shellac (Physical Data) | ||
|---|---|---|
| Colour | Gardner in 20% ethanol | max 16 |
| Acid No. | (DAB 9) | 65-80 |
| Arsenic | (DAB 9) | max. ppm 1.5 |
| Ash | (DAB 9) | max. % 0.2 |
| Insolubility in hot alcohol | max. % 0.2 | |
| Melting Range | (DAB 9) | 65-85 C |
| Moisture | max. % 2.0 | |
| Saponification No. | (DAB 9) | 190-230 |
| Wax | (USP XXIII) | max. % 0.2 |
| Dewaxed Orange Shellac (Physical Data) | ||
|---|---|---|
| Colour | Gardner in 20% ethanol | max 15 |
| Acid No. | (DAB 9) | 65-80 |
| Arsenic | (DAB 9) | max. ppm 1.5 |
| Ash | (DAB 9) | max. % 0.2 |
| Insolubility in hot alcohol | max. % 0.2 | |
| Melting Range | (DAB 9) | 65-85 C |
| Moisture | max. % 2.0 | |
| Saponification No. | (DAB 9) | 190-230 |
| Wax | (USP XXIII) | max. % 0.2 |