Gum Paste
1 ounce, or a little more of gum tragacanth (gum dragon). 8 ounces of finest powdered sugar. 8 ounces of corn starch.
The gum must be soaked 12 hours or more before it is used. Put it in a cup with half a cup of water, cover to keep out dust and set it on a warm shelf. When dissolved squeeze it through a clean towel by twisting with considerable force. Scrape up the gum, place it on a dish, add the sugar a little at a time and work them together with a paddle or wooden spoon. Add a drop of liquid blue to whiten it. When the sugar is all in begin adding the starch the same way. Pull out the paste as it becomes stiff and double and pull again, and when all the starch has been worked in the paste is ready for use. It may be pressed into shallow molds of fancy figure, made in plaster of paris, or in carved boards and left in them till dry and hard.
This is the old confectioner's modelling paste, the ancestor of what cake decorators now buy in tubs. The proportions are unusual by modern standards — half cornstarch — which gives a paste that dries bone-hard and takes a mould crisply, rather than one meant to be eaten with pleasure.
- The hinge: work it stiff, then keep it coveredGum paste skins over in minutes. Keep the mass under a damp cloth or in a sealed bag and take out only what you are shaping, or the surface will crack as you work it.
- Gum tragacanthStill sold, usually as a powder rather than the ribbons or flakes this recipe assumes. Powder hydrates in a few hours rather than twelve; whole gum genuinely needs overnight. One ounce is about 28 g to a half cup (120 ml) of water, which makes a thick mucilage.
- Straining through a towelUndissolved gum leaves lumps that show up as hard specks in a moulded figure. Twisting it through a clean cloth is the whole point of the step; a fine nylon sieve does the same job with less waste.
- "Finest powdered sugar"This means confectioners' sugar, sifted. Modern powdered sugar usually contains up to about 3 percent cornstarch, so the finished paste will be slightly starchier than the author intended — no practical difference here.
- Liquid blueA trace of blue optically cancels the yellow cast of gum and sugar, the same trick as bluing white laundry. Use a pinpoint of food-grade blue gel colour. Laundry bluing, which some period kitchens kept on hand, is not food.
- Plaster of paris mouldsRaw plaster is porous and absorbs whatever has been in it. Modern practice is silicone or food-grade polycarbonate moulds, lightly dusted with cornstarch so the paste releases.
- DryingLeft in the mould on a warm dry shelf, small pieces harden in 12 to 24 hours; thick ones take several days. Humidity is the enemy — a damp kitchen will leave the paste tacky indefinitely.
- Yield and useAbout a pound of paste, enough for a good number of moulded flowers, plaques or figures. It is technically edible but sets rock hard and was meant as decoration to be lifted off the cake, not chewed.
Gum tragacanth, the dried sap of several Middle Eastern Astragalus shrubs, has been the confectioner's binder for centuries — English recipes for "gum paste" and moulded sugar work appear well before 1700, and the material reached the same European markets as gum arabic. By the time this book was written, American pastry cooks were expected to turn out moulded ornaments, baskets and set pieces for hotel and banquet work, and a paste that could be pressed into a carved board or a plaster mould and left to dry hard was a standard part of the trade. The carved wooden boards mentioned here belong to an older tradition still, shared with springerle and marzipan moulds. The formula has never really disappeared: commercial gum paste and the tylose powders sold to cake decorators today do the same job the tragacanth did, with a modified cellulose gum standing in for the shrub.