Another method of negative intensification, especially for a stronger result, is to use mercury and ammonia. That is, to bleach your washed negativle out in a saturated solution of bichloride of mercury, wash and then immerse in a solu tion of ammonia, about half an ounce of ammonia to 20 ounces of water. This is a very strong intensifier and is very seldom used except for line copies and the like.
If a less strong intensification is desired, it can be bleached out and then blackened with a solution of sulphite of soda.
Occasionally there are negatives wWe the high-lights are too strong or harsh and yet the shadows need intensification. In such a case, one way to accomplish this is as follows : Bleach out with a saturated solution of bichloride of mercury and then, after washing thoroughly, touch the spots that are too harsh with a very weak solution of plain hypo on a piece of cotton and they will be reduced, but the hypo must be very weak, as its action is quite fast. After the high-lights have been reduced sufficiently, the bleached negative can be blackened to its original state by one of many methods. It can be placed in a weak solution of sulphite of soda, sulphide of soda, or ammonia, according to the amount of density that is wanted.
With a little intelligent practice, almost any kind of result can be accom plished. In fact, I do not think there is any limit to what can be done to a negative in the hands of a clever workman. A ground-glass, with a light under it, placed in a horizontal position to light negatives during intensification and reduction, is very helpful and makes a very convenient arrangement.
Again, there are times when but one small portion of a negative either has to be intensified or reduced, and especially in the case of reduction, the reducer is apt to get on to another portion of the negative where it is not wanted. One way to get around that is to proceed gs follows : Take a clean blotter and dry your negative (or a clean towel do the same thing) and then apply your reducer with a piece of cotton, pulled out to a fine point, in the center of the spot that is to be reduced. The reducer does not spread so rapidly on a plate that has been blotted or dried off and is thus more easily controlled. Some operators use an ear syringe, applying a strong intensifier or reducer with a thin film of water running over the plate at the same time. The thin stream of water going over the plate keeps the reducer or intensifier from causing a little ring around the spot being reduced.
Hot weather brings on its share of trouble, especially with double-coated plates, where the emulsion will become quite soft despite ice in the washing water, etc. There is also some trouble with films, they being coated on both sides. One way to remedy this is the method used by the pioneer dry plate workers in the old days, when plates were always soft. As the negative comes from the tray or tank after developing, rinse it off as usual and then immerse in about a 5 per cent solution of chrome alum for a second or so, transfer immediately to the fixing bath and then, unless your fixing bath is terribly old or very warm, your negatives or films will be almost hard enough to skate on.
Then, in the winter time, especially when using tanks or large trays of developer, there is difficulty in holding up the temperature. There is an electric iron on the market used for heating shaving water and the like, which is a very convenient attachment to have, as it will raise the temperature to any desired point with little trouble and one is very well repaid by such an investment.
The drying of negatives is also very important, if their quality is to be preserved. It is the habit of some dark-room men to dry their negatives in the dark-room. A Jar better plan, to my mind, is to have a place on the outside of the dark-room that is up off the floor and away from dirt, and the possibility of dirt flying on to them and away from the dampness of the dark-room.
Where several operators use the same dark-room and the same plate holders, especially when several different kinds of plates and films are employed, there is always the possibility of a plate holder lying around and nobody knows whether a panchromatic, Orthonon double-coated, or single-coated, or what kind of a plate is in the holder. A convenient way is to mark the holders with a grease pencil, such as is used to write on glass, specifying the kind of plate or film in the particular holder. Many of the large studios require their operators to return all unused plates or films to the proper boxes every night, which is a good plan, and if this method is employed liability of a mix-up is avoided.
In using pyro for developer, we all get our fingers stained, and many young fellows, going out among the ladies, and those of us who labor in "high brow" studios, have to remove the stain from our fingers. There are several methods of doing this. If the stain is not very bad and it has not been on very long, by immersing the fingers in the permanganate of potash reducer mentioned above, and seeing that the nails get plenty of it on, washing them a little bit, and then dipping them in the fixing bath a few moments, the stain will come off. If that does not work, wet your hands thoroughly with warm water to get them softened up, and apply a saturated solution of potassium permanganate to all of the stained parts ; wash them a little, and then bleach them out in a saturated solution of potassium metabisulphite. This will remove fairly obstinate pyro stains.
If the stains still stay with you, proceed to put more saturated solution of potassium permanganate on the finger nails, immerse in a mixture made of two or three drams of hydrochloric acid (Muriatic) and about eight ounces of water, to which is added four or five crystals of hypo.
This makes a kind of emulsion or soapy looking substance, but will remove the stains from your hands. I suppose if you left them in long enough, it would remove the hands too, as it is a little hard on the hands.