Blue paving bricks may be produced with almost any kind of clay that will stand a fair amount of heat, by adopting the same methods as in the former case of blood-red bricks, that is, the clay may be stained throughout, or an outside coating may be applied.

Stain for Blue Paviors

Ground ironstone. ... 20 parts

Chromate of iron..... 5 parts

Manganese......... 6 parts

Oxide of nickel...... 1 part

Use 1 part clay and 1 part stain for coating, and 50 or 60 parts clay and 1 part stain for staining through. Fire blue paviors very hard.

Buff Terra-Cotta Slip

Buff fire clay........ 16 parts

China clay......... 6 parts

Yellow ocher........ 3 parts

Ball clay............ 10 parts

Flint.............. 4 parts

Add water to the materials after mixing well, pass through the fine lawn, and dip the goods when soft in the liquid.

Transparent Glaze

Ground flint glass..... 4 parts

Ground white lead.... 4 parts

Ground oxide of zinc. 1/2 part

This glaze is suitable for bricks or tiles made of very good red clay, the natural color of the clay showing through the glaze. The goods must first be fired sufficiently hard to make them durable, afterwards glazed, and fired again. The glaze being comparatively soft will fuse at about half the heat required for the first burning. The glaze may be stained, if desired, with any of the colors given in glazed-brick recipes, in the following proportions: Stain, 1 part; glaze, 1 part.