Packaging and storage—
Preserve in well-closed containers, preferably in a cold place.
Labeling—
Label it to indicate whether it is bleached or is orange, and whether it is dewaxed or wax-containing.
Identification—
To 50 mg of Shellac add a few drops of a mixture of 1 g of ammonium molybdate and 3 mL of sulfuric acid: a green color is produced, and it becomes lilac on standing for 5 minutes.
Acid value—
Dissolve about 2 g of finely ground Shellac, accurately weighed, in 50 mL of alcohol that has been neutralized to phenolphthalein with 0.1 N sodium hydroxide, add additional phenolphthalein TS, if necessary, and titrate with 0.1 N sodium hydroxide VS to a pink endpoint.
[NOTE—For orange Shellac, titrate slowly, stirring vigorously, until a glass rod dipped into the titrated solution produces a color change when touched to a drop of
thymol blue TS on a spot plate.
] Express the acid value in terms of the number of mg of potassium hydroxide required per g of dried Shellac.
Wax—
Transfer about 10 g of finely ground Shellac, accurately weighed, and 2.50 g of sodium carbonate to a 200-mL, tall-form beaker. Add 150 mL of hot water, immerse the beaker in a boiling water bath, and stir until the solid is dissolved. Cover the beaker with a watch glass, and maintain the heat for 3 hours more, without agitation. Remove the beaker to a cold water bath. When the wax has floated to the surface, pass the solution through medium-speed quantitative ashless filter paper, transferring the wax to the paper, and wash the filter with water. Pour 5 to 10 mL of alcohol onto the filter to facilitate drying. Wrap the paper loosely in a larger piece of filter paper, bind with a piece of fine wire, and dry with the aid of gentle heat. Extract with chloroform in a suitable continuous extraction apparatus for 2 hours, using a weighed flask to receive the extracted wax and solvent. Evaporate the solvent, and dry the wax at 105
to constant weight.
Rosin—
Dissolve 2 g by shaking with 10 mL of dehydrated alcohol, add slowly, with shaking, 50 mL of solvent hexane, wash with two successive 50-mL portions of water, filter the washed alcohol–solvent hexane solution, and evaporate to dryness. To the residue add 2 mL of a mixture of 1 volume of liquefied phenol, ½ volume of dehydrated alcohol, and 2 volumes of solvent hexane. Stir, and transfer a portion of the solution to a cavity of a color-reaction plate. Fill an adjacent cavity with a mixture of 1 volume of bromine and 4 volumes of solvent hexane, and cover both cavities with an inverted watch glass: no purple or deep indigo-blue color is produced in or above the liquid containing the residue.
731
—
Dry it at 41 ± 2