Collodions consist basically of a thick, colourless, syrupy liquid, made by dissolving guncotton (pyroxylin) in a mixture of ether and alcohol or with acetone. When painted on the skin the solvent evaporates, leaving behind a tough protective ?lm that is useful for covering wounds. Flexible collodion – or collodion as it is often known – contains 1·6 per cent of pyroxylin, with colophony, castor oil and alcohol (90 per cent) in solvent ether. It should be kept in a well-sealed container. Being relatively elastic, it does not crack through the movements of the skin.
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