PAINTS and Varnishes are used by the engineer and builder for covering the surfaces of wood, iron, and other materials, in order to protect them from the action of the atmosphere, or to improve their appearance.
It will now be necessary only to give a few particulars regarding the paints and varnishes in common use on engineering and building works.
The paints used by the engineer and builder as a rule consist of a base1 (generally a metallic oxide) mixed with some liquid substance known as the vehicle; upon this, permanency of the paint depends.
It will be an advantage to glance at the properties of the substances used to effect the various objects above mentioned before describing the paints most commonly made from those substances.
The materials most commonly used for the purposes above mentioned are as follows :-
Spirits of turpentine.
1 Sometimes called a pigment, but here called the base in order to avoid confusion with the pigment added to give the colour; see p. 413.
Ochres, lampblack, umber, sienna, and many metallic salts, the principal of which are mentioned at pages 413 to 417.