“For 100 lb. of wet skin washed ready for bating, about 1 lb. of erodin is required. Or in the metric system, 1 kilo. wet skin requires about 10 grm. erodin. The strength or concentration of the bate must not fall below 3 grm. per litre of bate liquor, i.e. 1⁄2 oz. per gallon.
For preparing the bate a sufficiently large cask or tub carefully cleaned and steamed out is placed near the bating paddle. The cask should be fitted with a steam pipe easily screwed on and off, and also furnished with a clean cover.
The requisite quantity of erodin is weighed out and put into the tub with fifty times its weight of water, and the whole brought up to a temperature reaching but not exceeding 40° C. (104° F.) by direct admission of steam, thoroughly stirred, and the pure culture of Bacillus erodiens added to the mixture. The temperature must not be allowed to fall below 25°C. (87° F.), and a little steam should be admitted first thing in the morning, again at noon, and in the evening, to bring the temperature up to 40° C. (104° F.).
A practical mode of procedure is as follows:—On Friday make up and start fermenting twice as much erodin as will be required for a day’s work. This is allowed to remain under the above-mentioned conditions until Monday. On Monday half the amount will be used for bating; this is replaced by an equivalent amount of fresh erodin powder, dissolved in fifty times its weight of water, which is added to the already fermented erodin in the tub. Proceed in this way each day until the following Friday, when there will be left in the tub sufficient erodin for one day. This is put into a smaller tub for use on Saturday, and the cycle of operation begun again.
One pure culture of Bacillus erodiens should be used for every 11 lb. (5 kilos.) erodin powder or less quantity.
Suppose the amount of erodin required for a day’s work to be 11 lb. (5 kilos.), then on Friday 22 lb. (10 kilos.) erodin must be mashed as above described in 110 galls. (500 litres) water, 2 pure cultures added, and allowed to ferment until Monday.
On Monday half of this is used, and to the remainder 11 lb. (5 kilos.) erodin and 55 galls. (250 litres) water is added. This is repeated on Tuesday, Wednesday and Thursday; and on Friday half is used and the remainder put into a separate cask for use on Saturday, and in the mashing cask a fresh quantity of 22 lb. (10 kilos.) erodin with 110 galls. (500 litres) water is made up for use next week.[104]
[104] Mr. Wood has found that in many cases it is unnecessary to start afresh at the end of each week, but that additional quantities of erodin solution with the accompanying bacterial culture may be added continuously to the stock-tub as required. In puering, the concentrated solution from the tub may be diluted with 4 to 6 times its volume of warm water. The diluted liquor should usually only be used for one pack of skins.
On Saturday the remainder of the old mash is used up.
In case this mode of procedure is for any reason not suited to the conditions of work, erodin may be used by making up every day a fresh quantity with fifty times its weight of water, adding the pure culture, and allowing it to ferment three days before use.” In some cases the solution may be used for several consecutive packs, merely adding water and a small quantity of erodin without a new culture.