Part 103

Mazarine blue 1 part Glaze 7 parts

For royal blue use 1 part stain to 6 parts white body, and glaze unstained.

«Blood-Red Stain.»—Numerous brick manufacturers possess beds of clay from which good and sound bricks or tiles can be made, the only drawback being that the clay does not burn a good color. In many cases this arises from the fact that the clay contains more or less sulphur or other impurity, which spoils the external appearance of the finished article. The following stain will convert clay of any color into a rich, deep red, mixed in proportions of stain, 1 part, to clay, 60 parts.

«Stain.»—

Crocus martis 20 parts Yellow ocher 4 parts Sulphate of iron 10 parts Red oxide of iron 2 parts

A still cheaper method is to put a slip or external coating upon the goods. The slip being quite opaque, effectively hides the natural color of the brick or tile upon which it may be used.

The process is to mix:

Blood-red stain 1 part Good red clay 6 parts

Add water until the mixture becomes about the consistency of cream, then with a sponge force the liquid two or three times through a very fine brass wire lawn, No. 80, and dip the goods in the liquid as soon as they are pressed or molded.

«Blue Paviors.»—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 {167} 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 1⁠/⁠4 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.

«SPECIAL RECIPES FOR POTTERY AND BRICK AND TILE WORKS:»

«Vitrifiable Bodies.»—The following mixtures will flux only at a very high heat. They require no glaze when a proper heat is attained, and they are admirably adapted for stoneware glazes.

I.—Cornwall stone 20 parts Feldspar 12 parts China clay 3 parts Whiting 2 parts Plaster of Paris 1 1⁠/⁠2 parts

II.—Feldspar 30 parts Flint 9 parts Stone 8 parts China clay 3 parts

III.—Feldspar 20 parts Stone 5 parts Oxide of zinc 3 parts Whiting 2 parts Plaster of Paris 1 part Soda crystals, dissolved 1 part

«Special Glazes for Bricks or Pottery at One Burning.»—To run these glazes intense heat is required.

I.—Cornwall stone 40 parts Flint 7 parts Paris white 4 parts Ball clay 15 parts Oxide of zinc 6 parts White lead 15 parts

II.—Feldspar 20 parts Cornwall stone 5 parts Oxide of zinc 3 parts Flint 3 parts Lynn sand 1 1⁠/⁠2 parts Sulphate barytes 1 1⁠/⁠2 parts