Home › Ornamental Icing › Crystallization
Crystallization
Crystallization consists in simply covering the cake while the icing is wet with granulated sugar, plain or pink. (For coloring sugar pink see "meringue icing"). Or you can use pink or white sugar or rock candy crushed. If you wish to crystallize only a portion of the icing, and that in any particular design, first allow the icing to dry, then wash the part you wish crystallized with white of egg or gum-water, and cover it with the sugar; then shake off what will not remain on.
This is a finishing technique rather than a formula, and the whole thing turns on moisture: the sugar has to meet an icing surface that is still tacky, or it simply falls off. A few notes on the materials, which have mostly survived under different names.
- Work fast, while the icing is wetPlain confectioners' icing skins over quickly, and royal icing faster still. Scatter the sugar as soon as the last stroke of the spatula is down, one section of the cake at a time if it is a large one.
- What sugar to useNineteenth-century granulated sugar was generally coarser and less uniform than today's. For the glittering effect intended, use sanding sugar or coarse decorating sugar; modern granulated will read as a matte crust rather than crystals.
- Gum-waterA solution of gum arabic in warm water, roughly one part gum to three or four parts water, left to dissolve for several hours and strained. It is still sold for cake decorating and is the better of the two adhesives given here.
- The raw egg whiteWhite of egg brushed on and never heated is the older option and carries the usual raw-egg risk. Pasteurized egg white, sold in cartons, brushes on identically, or use the gum-water instead.
- Pink sugarThe cross-reference is to the book's meringue icing, where the method of tinting sugar is presumably given. A drop or two of gel food color worked through granulated sugar with the fingertips, then spread on a tray to dry for an hour, gives the same result without clumping.
- Crushed rock candyBreak it in a heavy zip bag with a rolling pin and sieve out the dust, which will dissolve into the icing and dull the surface. Only the pieces you can see the facets on are worth applying.
- Catching the excessHold the cake over a sheet of parchment or a rimmed tray when you shake it off. What falls is clean and can go straight back into the jar.
- Masking a designFor the partial crystallization described, let the base icing dry hard first, several hours or overnight, then paint the adhesive only where the sugar should stick. A small stencil laid on the dry surface makes this far easier than freehand work.
- HumidityOn a damp day the sugar draws moisture and the crystals go cloudy and soft. Decorate in a dry room and keep the finished cake uncovered rather than under a dome.
The Dixie Cook Book belongs to the great wave of American compiled household manuals of the 1880s, and its note on crystallized icing reflects a moment when elaborately decorated cakes had moved from the professional confectioner's window into the ambitious home kitchen. Crystallized or "frosted" surfaces were part of a broader Victorian taste for glitter on the table, of a piece with spun sugar, sugared fruits and the sugar-work centerpieces that appear in contemporary confectionery books. Gum arabic, the adhesive named here, is the dried sap of acacia trees and had long been a staple of the confectioner's bench, used for pastilles, lozenges and gum paste ornaments as well as for making sugar stick where it was wanted.