In the days of sail, to preserve the life of canvas sails by dressing them with cutch. The sails were immersed in a cutch solution for two or three hours, then hung over a spar to dry. The resultant colour was a rich deep red. When the sail was dry the cutch was fixed in the canvas by brushing into the sail, or immersing it in a solution of 0.45 kilograms (1 lb) of bichromate to 18.2 litres (4 gals.) of fresh water, and this fixing process changed the colour of the sails to mahogany.
Subjects: Maritime History.