This section is from the book "The Principles And Practice Of Modern House-Construction", by G. Lister Sutcliffe. Also available from Amazon: How Your House Works: A Visual Guide to Understanding & Maintaining Your Home.
Enamelled bricks of several colours can now be obtained, - chalk white, ivory white, cream, buff, pink, and various shades of red, brown, blue, and green. Black bricks are also made, and "soft-glaze" bricks of the nature of majolica. The latter are frequently crazed on the surface, and are not considered as durable as hard-glaze bricks, Enamelled moulded bricks are also made, and also bricks with patterns printed in one or more colours.
Faience is a name which has been applied to a kind of glazed brick and tile. The material has been largely adopted for internal decoration, and in a few instances the external surfaces of buildings have been formed of it. Almost any colour can be produced.
The shape of bricks is a matter of considerable importance. The thickness is not a matter of much moment. Roman bricks were usually more like tiles than modern bricks, being little more than an inch thick, and I have in Spain seen new bricks only 1¾ inches thick; in this country, however, the thickness is usually somewhere between 2¾ and 31/8 inches, although many architects are now in favour of thinner bricks on the score of appearance. The length and breadth are of more consequence than the thickness; in order to obtain proper bond without undue cutting, it is essential that the length of the brick be twice the breadth plus the thickness of one mortar-joint, that is to say, if the breadth be 4¼ inches, the length should be 8 ¾ or 87/8 The reason for this will be apparent on considering the question of bond. Various more or less intricate shapes of brick have at different times been devised, but the common oblong is still almost invariably adopted, except for purposes of ornament.