Dyeing.—As the largest proportion of the hats are to be black, preparations are made to dye what la required daily for the various departments. Some makers prefer pans wholly heated by fire, asserting that the liquor is not damaged, weakened, nor affected in its nature the same as in those raised by steam. Others conduct the black dyeing in a large pan heated both by a ateam-coil of copper pipe and by fire. If possible, a large room on the ground floor, with a good north light, will be very advantageous, and ample room must be provided for opening-out the hats singly, as thia aaaists most materially in striking the colour very deep.
For a large pan, a cage, as shown at B (Fig. 821), is made to fit inside the pan A, and a windlass is attached to lift the entire " dye " or batch of hata at once. This will save much time and labour. The dyeing of hats is much more difficult to perfect than the dyeing of ordinary wool for wearing and other purposes, where the surface of the fibre sustains no damage. In the former case, the dye must satu rate the fibre intimately, or the colour will look very grey and dingy. The subsequent proceas of "sand-papering " seriously affects the aurface, and requires the presence of nothing but free wool, dyed thoroughly through each fibre, or an even colour will be impossible. The dye-pan A (Fig. 821), is of atout copper, built into brickwork, and allowing room around the edge for the workmen to walk and agitate the hats in the process of dyeing. The cage B is alao made of copper, to prevent active corrosion. The workman prepares the pan first for a batch, say 50 doz. of woollen hats, by extracting 90 lb. logwood in a warm bath ; the liquor is well stirred, and the gooda are then immersed. The heat of the pan muat not exceed 82° (180° F.): boiling would cause harshness in either fur or wool, as previously explained, by extracting the gelatine. The goods are thoroughly turned, while the pan ia kept at a regular heat. After 1 hour, they are removed, and each hat ia spread out carefully to expose it to the atmosphere, thia deepening the colour. They aro then again placed in the dye-pan, and the process ia continued for another hour. Previoua to this second immeraion, 15 lb. copperas and 3 lb. verdigris are added. After constant turning over during the second hour, the hats are taken out and laid singly on the floor, as before, remaining for about 20 minutes. A third immersion will complete the dyeing in a satisfaotory manner, if due care has been taken. Many dyers allow the hats to remain for only
40 minutes in the pan ; in fact, the shorter the time that the hats stand in dye, with due regard to colour, the better they will go through the final processes. A much favoured dye for common hats is to mordant them first in a weak bichromate of potash bath, separate from the dye-pan, and then to place them iu the liquor. The use of copperaa can be largely avoided by this process ; but some object to it, on the ground that the bichromate makes the wool hard and harsh. Yet many makers are able to bring back the softness, and commend the process.
The following is a capital dye for fine hats, producing a good bright black, the quantities named being for dyeing 100 hats at one operation. Into a copper containing 55 gal. boiling water, put 9 lb. best liquid extract of logwood at 30 degrees, 41 lb. crushed cashew bark, 41 lb. sandal wood in powder, and 21 lb. soda crystals. Enclose the whole in a linen bag or wicker basket, so that they do not settle at the bottom of the copper. When the ingredients are dissolved, put the hats in, and allow them to boil gently for 2 hours. Then take them out and let them get quite cold. Now add to the bath, 3} oz. chromate of potash and 9 oz. sulphate of copper, and cool the bath by the addition of several pailfuls of water. Return the hats to the bath, and allow them to simmer for an hour. Again take them out, and let them get cold. After adding 2} lb. sulphate of iron, put the hats in again, and let them boil gently for an hour. Should they have a red appearance, add to the bath another 2i lb. soda crystals. After these operations, the hata must be piled up, and covered with a thick cloth for a day ; then subject them to a vigorous washiug, and eliminate the copper, using hydrochloric (muriatic) rather than sulphuric acid, as the latter always draws out the dye. When the copper is thus removed, pass the hats into Old water, in order to free them from acid. For the final operation, prepare a bath of Panama wood, just simmering, and place the hats in this for hour. This bath sets the colour, and gives brightness to the Lit. Upon taking them out, if soft hats, the water must be drained out of them by pressure. To produce a violet-black, the cashew must be replaced by the same weight of orchil. A blue-black is obtained by leaving out the catechu and sandal wood, and replacing them by extract of Cuba yellow wood at 30 degrees.