Then by slow degrees a proportion of " dryers " is added - usually equal weights of litharge and minium being used to the extent of 3% of the charge of oil; and with these a small proportion of umber is generally thrown in.
After the addition of the dryers the boiling is continued two or three hours; the fire is then suddenly withdrawn„and the oil is left covered up in the boiler for ten hours or more.
Before sending out, it is usually stored in settling tanks for a few weeks, during which time the uncombined dryers settle at the bottom as ” foots."
Besides the dryers already mentioned, lead acetate, manganese borate, manganese dioxide, zinc sulphate and other bodies are used.
How would you define dryers? Add your definition here.