_Example of Matt Glaze and Bright Glaze Mixes._--Two mixes are given below calculated to fuse at cone 04. One has a "matt" or dull velvety surface, and the other has a "bright" or shiny surface. The matt will be found more desirable for general work because it harmonizes better with flowers and foliage. The figures given below refer to units of weight. Metric weights (grams) are most convenient to use, but any units will serve so long as the same one is used throughout. The matt glaze should be of the consistency of thick cream, the bright glaze somewhat thinner.
MATT BASE Lead carbonate 154 Whiting 25 Canadian feldspar 83 Florida kaolin 51
BRIGHT BASE Lead carbonate 142 Whiting 20 Canadian feldspar 84 Florida kaolin 8 White oxide of zinc 8 French flint 44
The bases itemized above are colourless and there must be added to them from 3 to 6 per cent. of colouring material that will stand heat. A list of materials with their colours when fired is given on page 304, together with a few typical combinations of colours in quantity suitable to be added to the glaze bases given above. The following lists are by no means complete, and it is expected that the young decorator will make use of these colour mixtures simply as an introduction to quite extensive experimenting:
Black oxide of cobalt Blue Black oxide of copper Blue green Green oxide of chromium Yellow green White oxide of antimony Lemon yellow Red oxide of iron Yellowish brown Green oxide of nickel Dirty gray (for neutralizing) White oxide of tin Makes glaze opaque Black oxide of manganese Purplish brown Yellow ochre Yellow Burnt umber Brown
Dark brown Iron oxide 3 Nickel oxide 2 Manganese oxide 5
Light gray-blue Tin oxide 5 Cobalt oxide .5 Copper oxide 1.7
Blue-green Cobalt oxide 1 Copper oxide 7 Yellow ochre 4
Dark gray-blue Nickel oxide 5 Yellow ochre 3 Cobalt oxide 2 Copper oxide 1
_Applying the Glaze._--Before applying the glaze to the piece of pottery or bisque, the latter should be soaked in clear water for about five minutes or until the air is expelled from the pores. When this has been accomplished it should be removed from the water and all moisture should be wiped from its surface. The piece is then ready to be dipped into the glaze, or to have the glaze poured over it, if the size and shape of the piece make it more convenient to apply the glaze in this way. It is usually best to glaze the inside first, shaking out all the superfluous glaze before applying the glaze to the outside. During this process the piece must be held firmly but by as few points of contact as possible. These points of contact will generally need to be touched up before it is ready for firing.