This section is from the book "Experimental Cookery From The Chemical And Physical Standpoint", by Belle Lowe. Also available from Amazon: Experimental cookery.
Timbales and rosettes should be crisp, and the timbale shell should be thick enough to hold the material that is to be served in it. Usually a cup of flour to a cup of liquid produces a good texture, but a slightly larger or smaller proportion of flour to the liquid also makes a good timbale. The batter should be mixed until free from lumps to avoid thickened places in the finished timbale. If bubbles are formed during mixing or beating of the batter they interfere with the smoothness of the finished timbale and it is therefore better to let the batter stand until these bubbles disappear.
The timbale iron should be heated while the fat is heated in the deep fat kettle so that it will be the same temperature as the fat. If the timbale iron is too cold when it is dipped into the batter, the batter will not cling to it. The fat should be drained from the iron or the surplus wiped off with a paper towel before putting the iron in the batter. Otherwise the batter will not cling to the iron or large holes may be formed in the bottom of the timbale case from the surplus fat.