The hard, crusty surface of canes renders them practically impervious to water stains. A brown tone may be gained by scorching the canes in a gas flame - a gas-stove flame for preference. Bamboo workers generally colour up the articles after they are made. This is done by mixing suitable pigments, as vandyke brown, brown umber, or black, with French polish or spirit varnish thinned out with methylated spirit, a coat of clear varnish being applied afterward- for finish. If the canes have been stored in a damp place to render them soft, try a stain made by mixing vandyke brown with American potash and hot water.