(See also Ceramics, Enamels, Paints, and Varnishes.)

Glazes for Cooking Vessels

Melt a frit of red lead, 22.9 parts (by weight); crystallized boracic acid, 31 parts; enamel soda, 42.4 parts; cooking salt, 10 parts; gravel, 12 parts; feldspar, 8 parts. According to the character of the clay, this frit is mixed with varying quantities of sand, feldspar and kaolin, in the following manner:

Frit..........84

84

84

84

Red lead..... 1.5

1.5

1.5

1.5

Gravel....... 8

6

3

-----

Feldspar......------

2

5

8

Kaolin, burnt. 6.5

6.5

6.5

6.5

Glazes which are produced without addition of red lead to the frit, are prepared as follows. Melt a frit of the following composition; Red lead, 22.9 parts (by weight); boracic acid in crystals, 24.8 parts; enamel soda, 37.1 parts; calcined potash, 6.9 parts; cooking salt, 10 parts; chalk, 10 parts; gravel, 12 parts; feldspar, 8 parts.

From the frit the following glazes are prepared:

Frit..........86.5

86.5

86.5

86.5

Gravel....... 7

4.5

3

-----

Feldspar.....------

2.5

4

7

Kaolin, burnt. 6.5

6.5

6.5

6.5

Glazing on Size Colors

The essential condition for this work is a well-sized foundation. For the glazing paint, size is likewise used as a binder, but a little dissolved soap is added, of about the strength employed for coating ceilings. Good veining can be done with this, and a better effect can be produced in executing pieces which are to appear in relief, such as car-touches, masks, knobs, etc., than with the ordinary means. A skillful grainer may also impart to the work the pleasant luster of natural wood. The same glazing method is applicable to colored paintings. If the glazing colors are prepared with wax, dissolved in French turpentine, one may likewise glaze with them on a size-paint ground. Glazing tube-oil colors thinned with turpentine and siccative, are also useful for this purpose. For the shadows, asphalt and Van Dyke brown are recommended, while the contour may be painted with size-paint.

Coating Metallic Surfaces with Glass

Metallic surfaces may be coated with glass by melting together 125 parts (by weight) of flint-glass fragments, 20 parts of sodium carbonate, and 12 parts of boracic acid. The molten mass is next poured on a hard and cold surface, stone or metal. After it has cooled, it is powdered. Make a mixture of 50° Be. of this powder and sodium silicate (water glass). The metal to be glazed is coated with this and heated in a muffle or any other oven until the mixture melts and can be evenly distributed. This glass coating adheres firmly to iron and steel.

Glaze for Bricks

A glazing color for bricks patented in Germany is a composition of 12 parts (by weight) lead; 4 parts litharge; 3 parts quartzose sand; 4 parts white argillaceous earth; 2 parts kitchen salt; 2 parts finely crushed glass, and 1 part saltpeter. These ingredients are all reduced to a powder and then mixed with a suitable quantity of water. The color prepared in this manner is said to possess great durability, and to impart a fine luster to the bricks.