The firing of glaze is a process very similar to that employed in the production of bisque, already described. Greater care, however, must be taken in controlling the increase in temperature so that it shall be even and steady—free from all sudden flashes of heat. The cooling also should be very gradual and, as in bisque firing, the kiln should be allowed to get cool before it is opened. With this second firing the pottery is finished unless it should happen that a second coat of glaze is found to be necessary. If only a few spots need attention, this second coat is best applied with a brush.
PROBLEM: A VASE FOR LONG STEMMED FLOWERS
The tools required for making this vase are the same as those used for the bowl, and the process of building is much the same. The chief difference is that it is more difficult to preserve the profile in building because the added height and the greater weight tend to bulge the lower part. To meet this difficulty it will be necessary to set the work aside quite often in order to let the lower part harden sufficiently to support the upper part.
The Profile.—In preparing the profile the same rules hold as were applied in working up the problem of the bowl. It will be well to remember, however, that the curves of a vase must be treated with greater reserve as to their lateral projection than was necessary in the case of the bowl—i. e., the curve of a vase should be enclosed within a rectangle narrower in comparison with its height than is the case with the curve of a bowl. The reason for this, of course, is found in the greater height of a vase in comparison with its diameter. The following figure shows three typical vase forms. If these curves be compared with those shown on [page 288], illustrating bowl contours, it will be observed how the height of the vase is emphasised in the greater restraint and subtlety of its curves. In the next illustration we have two "horrible" examples to which attention has already been called in the suggestions for the design of bowls. The dotted lines in the illustration show how these curves may be improved if, in either A or B, one element of the compound curve be made dominant at the expense of the other. If at the same time the diameter be made smaller in comparison with its height the attractiveness of the contours will be still more improved. Indeed, it will be a transformation from a profile that is positively bad to one that is very good.
Typical vase forms
Profile to be avoided
Decoration.—The problem of decoration is not very different from that of the bowl. Here again, however, the added height seems to call for greater accent by means of vertical or panel divisions. Unless this be understood there is some danger that the larger vertical spaces will seem to offer simply more room for horizontal bands, resulting in a barber pole effect.