Henry R. Blaney

“ It is sometimes advisable to regulate the quantity of dichromate. In hot weather, or for very thin negatives, the proportion of water should be doubled, while for very hard negatives only half the quantity should be used. In very hot weather it is often advantageous to replace about 30 per cent. of the water with the same quantity of alcohol.
The operation of sensitizing the tissue must be carried on in a room lighted by a window covered with a yellow blind. A flat dish of porcelain, glass, or papier maché, a squeegee, and a sheet of glass or zinc larger than the tissue, will be required. ”

“ Transparencies can be made same size of negative by contact and exposure to artificial light, or enlarged or reduced in the camera by daylight, with equal perfection in result. To make transparencies by contact place one of the Keystone thin crystal glass transparency plates over the negative in printing-frame, lay piece of dark soft material over it, close down the back, and expose to the light of the lantern or to a gas flame or other artificial light, for 10 to 30 seconds, according to density of negative, at a distance of 20 inches from the flame. ”

“ If the negative is made by the collodion process the matter is a simple one. The glass is treated with French chalk previous to collodionizing. After the negative is made and dried it is laid on a leveling stand and a solution of gelatine poured on it. When dry, it is readily stripped by running a knife all round. With ordinary dry-plates the method usually recommended is to immerse them in dilute hydrofluoric acid. The difficulty often experienced here is in the lateral expansion of the film. This will largely depend upon the plate, or rather the quality of the gelatine used. ”

“ The addition of ammonia and alcohol to the sensitizing solution makes it easier to strip the paper from the copper plate, after the carbon tissue is mounted on the plate, and enables one to develop the resist in the water at a lower temperature than without it, thus avoiding pits in the darker portions and white specks or bubbles in the lights, should the water reach too high a temperature. ”

“ Experience here is the only guide, as the light varies as well as the density of the negative and the sensitiveness of the tissue. If one does not have an actinometer, a slip of albumen paper may be used; as soon as the paper has reached the darkest point, which is then called one tint, extend it so that a fresh portion comes out to the light, and so on for the different tints. ”

“ In cases where these are flat from over-exposure it is well to make a carbon transparency; intensifying the image with a strong solution of permanganate of potash, and from this make a fresh negative upon a slow or Carbutt transparency plate.
Mr. Horace Wilmer says: "The class of negative most suitable is such as gives a good result by any of the printing processes. A bright sparkling negative will always give a good plate, but I do not find that any satisfactory results can be got from a soft flat negative. The negative should be as perfect as possible. ”

“ The beginner is usually content to start with a modest outfit, but as interest grows the hunger for more artistic results calls for better facilities so that the apparatus must constantly be of a more improved pattern and contain all the latest fixings, till finally the question of improvement is entirely one of the value of the lens.
To suit this growing appetite we make a line of camera boxes unequaled for workmanship and convenient appliances. We can supply any stage of hunger, and make to order to suit any whim. ”

“ Continuing Action of Light.—If the carbon tissue after exposure to the light, be kept in the dark for a little time the effect on the print will be precisely the same as if the exposure to light had been prolonged. This continuing action of light may often be utilized to advantage. Pictures known to be under-exposed will, if kept till morning, by that time have acquired the same force as if they had received the proper exposure.
Development consists simply in dissolving the gelatine unaffected by light, with hot water as the solvent. ”

“ The steel or zinc plate is then to be exposed to light to completely harden the mixture all over, and is then treated exactly as in my other engraving process; that is, pressed into soft metal by hydraulic pressure, electrotyped, and then the surface is aciercised or coated with steel. The dark parts are thus represented by a coarse grain, the middle tints by a medium grain, and the finest shades by the most infinitesimal particles, thus meeting all requirements necessary to a successful photo engraving process. ”

“ After cutting it up to the required sizes, which should be conveniently smaller than the dish to be used for sensitizing, it should be kept flat under a metal plate.
Sensitizing the Tissue is the next operation. This is performed in a solution of potassium dichromate rendered alkaline with ammonia. Tie over the mouth of a two-gallon jug a piece of muslin, to form a kind of bag, into which place fifteen ounces of potassium dichromate, then fill up the jug with water and allow it to stand until the dichromate is dissolved and the solution becomes cold. ”