Paint Technology and Tests

Linseed Oil. The seed of the flax plant which is extensively grown in North Dakota, Argentine Republic and Russia, contains approximately 36% of oil which may be obtained by grinding, heating, and expression. Ripe native seed generally produces a pale oil of little odor; the oil from Argentine seed often having a greenish tint and an odor resembling sorghum. While filtering, pressing and ageing will remove considerable of the ("foots") mucilaginous matter, phosphates, silica, etc., from the oil, the better grades which are intended for varnish making are often refined with sulphuric acid. A light colored oil which may be heated without "breaking" results from this treatment, but such oils are apt to contain considerable free fatty acid, unless they are washed with alkali subsequent to the sulphuric acid treatment.