The mode of dipping is the same as for hard hats ; less heat in stoving will suffice.
Spirit Proofing.—Some account must now be given of the most popular preparations, both English and American, for the proofing of fine goods, technically known as "spirit proofing." The stiffening of these goods, like that of all others, requires careful attention on the part of the maker, in order to ensure good results. The climate in which the hats are to be worn should influence the character of the proofing. The dampness of the English air demands a much harder stiffening than is requisite in America. In the largest manufactories in the latter country, where fine hat-making, both hard and soft, has reached, a very high state of perfection, the moat favoured preparation is 20 lb. of orange shellac, dissolved in the cold in 5 gal. spirit (methylated or alcohol), in a close vessel, with repeated and careful stirring, to keep it from "lumping," and sticking to the bottom. The vessel commonly used is in the form of a barrel or churn. When fully melted, the " stiff" is made ready for use by being thinned down by spirit. The strength is not gauged by hydrometer, but is judged by actual application by an experienced hand. A good stiff brush is used to put in the proof. Most strength is given to the brim, as in the first case.
Another American proof; of a cheaper kind, for soft hats, is made in the steam proof-pan, by dissolving 9 lb. shellac with 18 oz. carbonate of soda in 3 gal. water. The soda is first gradually introduced, and is soon dissolved ; then the lac is put in, and stirred occasionally for about an hour, by which time it will be dissolved. The whole is then left for an hour or two, when it may be taken out and set to cool. It will be found better if allowed to stand for a few days after being made. When used, it is reduced by water, as explained in the first mixing of hard proof for woollen hats, the strength being 2°-10° Tw., according to the thickness of the felt. This mixture will be found very good for soft or semi-stiffened hats. It is the habit amongst some makers to add 3 oz. salt. The salt counteracts the soda, and the hats may be blocked immediately after stiffened, thereby saving time, and dispensing with the use of the stove. The following ,mixture is esteemed by some English makers :-7 lb. orange shellac, 2 lb. gum aandarach, 4 oz. gum mastic, lb. rosin, 1 pint solution of copal, and 1 gal. wood naphtha or methylated spirit. The lac, aaudarach, mastic, and rosin are dissolved in the spirit, and the solution of copal is added last. This is rubbed into the body with a brush, like the former spirit proof for fine hats. The hats, both
hard and soft, are placed in the stove at a temperature of about 82° (180° F.) if of wool ; less heat will serve the purpose of spirit-proofed hats, and care must be taken lest they catch fire. Bringing the goods from the stove, a steamer is provided, which will hold two rows of pegs, on which to place them while undergoing the steaming process. This chest, Fig. 820, is composed of wood, about 2 in. thick at the sides and bottom, bolted at the sides with cross-bars to strengthen it. The figure shows the inside of the chest with the lid open.
A strong fastening must be attached to the lid, to prevent its being lifted by the pressure of the steam, while the hats are undergoing the process, which lasts for 20-30 minutes.
The lid A is raised by a chain attached to a pulley B, secured in a stout pillar, and enabling the operator to adjust the lid to any height by means of .a balance-weight attached at the other end ; C is a row of wooden pegs, on which to hang a pile of hats, say 6, 8, or 10, as required ; D is one of a, series of perforated pipes fur injecting the steam evenly throughout the Placing hats on these various pegs, the lid is brought down and securely fast ened, and steam is turned on for 20 minutes. On opening the chest, the bats are taken by the taper end, and dropped singly upon the floor to set until perfectly cool. When a sufficient number is accumulated to fill the hot-stove, the goods (if for hard hats) are passed into this stove, and kept at a temperature of 82° (180° F.) for 6 hours, allowing the heat to gradually decrease from that time. In the steaming process, the stiffening is cleaned from both the outer and inner surface, by the equal pressure of the steam on both sides. It needs careful attention to avoid scorching the fibre, as this will destroy the peculiar gelatine inherent in the hair of animals, and which accounts for the fine softness of the finished article ; if once extracted, the latter is left wiry and harsh. This completely spoils its character, and will explain a fact hitherto not generally accounted for, that the dry, harsh sensation is the result of this extraction of gelatine. In dyeing, the same care should be taken not to destroy it by boiling. After a thorough keying, performed in a special apartment if possible, on account of the dangerous character of the work, all the goods are removed to the dye-house, where a number of copper pans are fixed for the reception of the hats, no other material so well withstanding the corrosive action of the acid accumulated in the hats.