This method, however, has been found too costly to work commercially; the usual method to get rid of curling is to dip the prints directly into water raised to a temperature of i 15 Begs. Fahr., and then to lay them face downward on a slightly inclined tray, and pat them gently until no tendency to curl is apparent. In this position they should be allowed to remain for about ten minutes, after which washing should be continued, at the same time gradually reducing the tem perature of the water until cold water can be safely used.
With collodion paper, the precautions against dampness are not so much needed as with the gelatine.
Another method is to place the prints, after washing, in a bath of alcohol, and from this direct to the toning bath. • Collodion prints require a thorough washing before toning, or the action will be uneven. It should be remembered that water does not permeate the collodion film so readily as the gela tine, although against this it must be said that the collodion film is far thinner.
Toning and is of opinion that collodion aristotypes require a much weaker toning bath than albumen or gelatine. It is certainly a fact that if the bath is too strong, a very uneven effect is produced. The process that he recommends is to wash the prints well in salt and water, rinse and tone in Borax solution (1 per cent.) t,000 parts Gold solution (I per cent.) 20 to 3o parts The manufacturers of the Ilo collodion paper recommend the following: Pour the gold solution into the sulpho solution, giving you 140 ounces bulk. This bath keeps, and can be used repeatedly by adding gold and sulphocyanide ammonia.
Toning will be done in two or three minutes. If a warm tone is desired, prints must be taken out when quite red.
While for Kalona paper, which is also prepared with collodion, the following are given: No. t.
Water 48 ounces Acetate soda 75 grains Borax 75 grains Add neutral gold enough to tone.
No. 2.
Water 48 ounces Phosphate soda go grains Add neutral gold enough to tone.
No. 3.
Water . 48 ounces Tungstate soda iso grains Add neutral gold enough to tone.
Have plenty of bulk to toning bath, so that each print is singly and thoroughly saturated. Toning baths should be made up at least twenty-four hours before using. Be sure toning bath is slightly alkaline at all times, testing occasionally with litmus paper. The toning bath should not work too quickly, from eight to twelve minutes for each batch of prints. After prints are toned, place in large intermediate water bath before fixing.
Fixing is done in Hyposulphite of sodium 3 ounces Water 64 ounces In this solution the prints must be allowed not less than fifteen minutes.
A good plan, after this treatment, is to rinse them and immerse for five minutes in a fresh fixing bath. This method of double fixation is now very largely adopted, as it insures the com plete elimination of the hyposulphites of silver.
The combined toning and fixing bath can also be used, and is preferred by many on account of its simplicity and regularity. The instructions given with the Ilo paper for this method of treatment are as follows: Dissolve thoroughly, then let it stand for twenty-four hours to settle, and use the clear portion. Bath of above proportions will tone and fix 500 to loo cabinet size prints.
The bath must not be colder than 55 degs. nor warmer than 6o degs. Fahr. Take the temperature with a thermometer just before using, and if warmer than 6o degs., cool by adding a small piece of ice.
The amount of hypo in the toning and fixing bath must be kept up to the original standard, therefore a saturated solution of hypo should always be at hand-1 pound hypo to 2 pounds (I quart) water. Measure the bath as you put it in your toning dish, so you will know just the quantity you are using. If you are using a quart, for every twenty-five or thirty pints toned and taken from the bath, add one ounce of this hypo solution to the portion of the bath you are using. If you are using a pint, add ;4 ounce of the solution for every twenty-five or thirty pints toned and taken from the bath; and if you are using half a gallon, add 2 ounces of the hypo solution for every twenty-five or thirty pints taken from the bath, etc., etc.
You can use the bath over again as long as it will work and give satisfactory results. When you have finished, simply pour the portion you have been using into a separate vessel, and, to tone next batch of prints, use half old and half new bath.
Dissolve two or three bottles of the chemicals at a time, so you will have i or 2 gallons of the solution as stock always on hand. It keeps indefinitely in an open vessel, and, by having a quantity this way, you get much more satisfactory results. If your bath gets muddy, let it stand to settle, and use the clear portion and reclaim the balance by filtering.
Vogel is of opinion that, with collodion paper, the toning process should be as rapid as pos sible. When the time taken is too long, the fine details become gray, while the shadows keep warm.
Lead salts in the toning and fixing bath hasten the toning action. He recommends the following three combined toning and fixing baths: