In 1831, William Macfie was setting up a new 'candy stove' in his Greenock refinery. (Letter)
From a very long Supplement to The Penny Magazine of April 1841 entitled "A Day at a Sugar-Refinery"...
We may here perhaps briefly explain the mode of reducing sugar to the state called sugar candy. The process is not conducted at sugar refineries, but is nearby as follows:- When the cane juice has been clarified and boiled, it is placed in old moulds, having their lower ends stopped with linen, and crossed at intervals with strings or small twigs, to retain the sugar as it crystalizes. The moulds are then deposited in a cool place; and in proportion as the syrup cools, crystals are formed. In about nine or ten days the moulds are carried to the stove and placed in pots, and a small aperture made, through which the syrup can drop slowly. When the syrup has drained off, and the crystals of sugar candy are become dry the moulds are taken from the stove and broken in pieces to disengage the sugar, which adheres strongly to the sides of the moulds. By previously tinging the syrup with cochineal or some other colouring substance, the candy may be made to assume any desired hue. The arrangement of the utensils used in the process is generally somewhat as follows:- a stove is set apart, the entrance into which is on the ground floor, as near as possible to the pans: the top is usually from ten to fourteen feet above the ground, and covered like the top or crown of an oven. Beams are fastened into the wall, at a distance of twenty six inches from each other, and sufficient to bear a very large weight; upon which strong planks are laid when wanted. The candy pots are placed upon the planks, and remain there until the process is finished. The pots are usually made of thin copper, without feet, and are perforated around the lower part with numerous holes, the purpose of which is this:- a course white thread is drawn by a needle through a hole in one side of the pot, carried across to a similar hole in the other side, brought back again through a third hole; and so backwards and forwards till the lower part of the pot is traversed by several lines of thread; after which the holes are stopped. Each string forms a nucleus round which the candy crystalizes; an effect which used formerly to be produced by the use of small twigs.
From an extract of a few pages from an aged untitled encyclopedia ...
This well known material is nothing more than sugar brought to a regular form by slow crystalization. The management of it differs considerably from that of loaf sugar. To prepare it, the syrup is clarified as usual, and boiled down to a certain point, but not so much as for making loaf sugar. It is then poured into large oblong moulds or boxes, into which a light frame is previously fixed, holding, stretched from one end to the other, a number of cords of packthread. The mould filled with syrup is then put into the drying stove, and suffered to remain undisturbed for a considerable time, during which the sugar gradually deposits in crystals around the threads. The mould is then removed, and the frame is lifted out with every thread thickly and very beautifully encrusted with the candy, and is afterwards drained to free it fom the adhering syrup. Sugar candy is more transparant and much harder than common sugar. The brown sort crystallizes full as regularly as the white, but becomes clammy and deliquescent in a damp air, while the white remains always dry. On account of its superior hardness it is less soluble than loaf sugar, and appears to have much less taste, but it has full as strong a body of sugar, and would be excellent calculated for preserving all vegetable food if the price were lower.