For the inside of most pieces a transparent glaze is used, whether the outer glaze is to be transparent or opaque.
All of the odds and ends of transparent glaze, no matter what the colour, that are left after each glazing, are poured into a large bowl or other vessel which is kept for the purpose. The mixture of all colours in this combination of glazes makes a neutral tint which harmonizes most agreeably with the outer glaze, whatever its colour.
It is applied as follows:
To Glaze the Inside of a Piece of Pottery
Take a small cupful of transparent glaze, and, holding the piece of pottery over the large vessel containing the liquid, pour the cupful of glaze into it, rolling it around the inside of the piece quickly but carefully, so as to have it cover the entire inner surface. Then turn the piece deftly and suddenly bottom up, so as to empty it into the large vessel without letting any of it drip over onto the outside of the piece. Should this happen, by accident, rub it quickly off with the fingers.
The Outside Glaze and How to Apply It
The most satisfactory finish for the outside of fine pottery is a mat or opaque glaze in any soft dull shade of green, brown, blue, yellow, or the red obtainable with red oxide of iron. For an art pottery, composed of fire-and blue-clay, which requires a strong heat, the following glaze is applicable:
Gray-Green Mat-Glaze
Mix