ANALYSIS OF SHELLAC
There are different tests for shellac, some of which are mandatory and some are optional.
Among the mandatory requirements as specified by
Indian Standards Institution (ISI) are:
(i) Matter insoluble in hot alcohol
(ii) Colour Index
(iii) Tests for detection of rosin, orpiment and other arsenical
Among the optional tests are:
(i) Volatile matter
(ii) Wax percent
(iv) Matter soluble in water
(vi) Life or heat polymerisation test
(vii) Acid value
(viii) Iodine value etc.
The matter insoluble in hot alcohol varies from
0.2% in very high grade of dewaxed decolourised shellac to
2.5% for inferior grades of shellac.