Silk Degumming

Abstract

The chemical properties of sericin are reviewed. When alkalies or soap react upon sericin a progressive degradation of the sericin particle takes place in solution after the sericin leaves the silk. The grams of sericin combining with one gram equivalent of soap or alkali when a point of equivalence is attained in solution may be expressed by the equation B = — 1000 log₁₀R — 2180 where B is the binding weight of sericin R is the initial ratio of gram equivalents of total soap or alkali per gram of total sericin initially present.

This same relationship holds for solutions of sodium hydroxide, sodium carbonate, sodium silicate and sodium, oleate for values of B from 140 to 2100, the experimental range. The point of equivalence is taken as neutrality with phenolphthalein when the sericin solution is titrated with standard sodium hydroxide or sulphuric acid in a 40% alcoholic solution. At this point of equivalence sodium-sericin still possesses degumming power so that the values of B just noted do not apply to the binding weight or sericin as it is just removed from the silk.