1 tablespoonful of soft glaze,
½ tablespoonful of stannifère, and
½ tablespoonful of China clay,
together on a stone or glass slab with a palette knife, adding ¼ teaspoonful of gum-arabic and enough water to make the consistency a little thicker than thick cream. About ¼ teaspoonful of carbonate of copper added to this mixture (and ground thoroughly into it with the palette knife) will make a light gray-green. For deeper shades increase the quantity slightly. The tint appears much lighter than it will when fired; indeed, in the colouring of glazes, as in painting on china, the worker needs a great deal of faith, for until the magic of the kiln brings out the colours one would never guess what they were to be.
In applying the glaze, place your piece bottom up on a table, or other flat surface. Dip a soft, flat paint-brush into the bowl of glaze, and beginning with the bottom, paint it on in short strokes in every direction—what an artist would call cross-hatching—and overlapping slightly like the shingles on a house. The bottom receives but one coat of glaze, as it is liable to stick in firing and be uneven if it has more than one. Next start at the sides, near the bottom (as the piece stands upside down), and paint down for an inch or two all around. The piece is then set right side up, providing, of course, that the bottom is dry, which it will be undoubtedly, and the rest of it is glazed. From time to time stir up the glaze from the bottom, that it may be thoroughly mixed.
The edge especially should be carefully covered, and the outer glaze may even be brought over inside the piece a little. Before applying the second and third coats (for the piece receives three) two teaspoonfuls of gum tragacanth, well mixed according to directions, are added to the glaze. In putting on the second coat, the piece is again placed upside down on the table, and beginning where the sides join the bottom, the glaze is applied as before. The sides and top edge only are glazed this time. The third coat, which is put on when the second is dry, is begun at the top edge, covering it well, and is ended gradually and unevenly half way down the sides.
Pale-green Mat-Glaze
To make a lighter shade of green, with just a hint of yellow to soften it, add to half the quantity of the glaze first mixed as much again of the uncoloured glaze and a slight sprinkling of yellow.
It will be seen from these directions how much the colouring of glazes is like the blending of pigments for a picture. It is a delightful field for experiment, and the element of chance is supplied by the kiln, which often does unexpected and interesting things to one’s colours and glazes—leaving here, a touch of brown about the rim to relieve an expanse of green; there, a metallic tinge almost like lustre; and again the biscuit peeps through the glaze, giving a warmer tone to the edge of a decoration.
In mixing the glaze for a piece that has been fired in the biscuit, make it a little thicker than that for use on the green clay—about the consistency of whipped cream. It is applied somewhat differently, too. A potter would tell you to "rag it on"—that is, put it on with firm, short strokes, using the ends of the hairs of the brush instead of the flat part. Let each coat dry well before the next is applied. Three or four coats will be necessary, except for the bottom, which receives but one. After the first coat, gum tragacanth is added, as in glazing on green clay. The fourth coat need not entirely cover the piece, but the top should be carefully glazed. If for any reason the pottery has to be re-fired, it should be reglazed, but two coats only will be necessary, and the glaze need not be quite so heavy as that used on the biscuit. Do not be discouraged if your pieces need a second or even a third firing, for often the most beautiful results are obtained by re-firing. Quality—that combination of richness, and depth of colour and texture—rarely comes with the first firing.