This section is from the "Studio light a magazine of information for the profession 1914" book, by Sara F. T. Price. Also see Amazon: Studio light a magazine of information for the profession 1914.
There are a number of photographic troubles which crop up each year as soon as it begins to get real warm, and which are invariably due to the same conditions which prevailed at the same time last year. It's a good time just now to caution the printer and the dark-room man that they may be on the watch for warm weather difficulties and prevent them.Comparisons are not always odious, and many times a good point is made clearer, sinks in deeper and remains fixed in the mind, because of a comparison that fits.And still it is sometimes hard to find a parallel that will clearly illustrate a particular point in photographic manipulation.
FROM AN ARTURA IRIS PRINT
By Geo. M. Edmondson Cleveland, Ohio
Conditions of water encountered in hot weather will not cause Artura prints to blister, frill, stain or become soft and sticky. However, the chemical action of the developer is changed by a decided variation in temperature.
Developing a print with warm developer gives much the same result as hitching an extra team of horses to a plow and driving across a very rough field on a run. The plow will only hit the high spots and the soil in the depressions of the ground is not disturbed.
In effect, the result is much the same when your Artura developer is so warm that it runs away from you. Only the high spots of the print, the shadows, are touched, the developing action being too fast to allow any great amount of developing energy to reach the depressions in the emulsion, so the detail of highlights and half-tones is lost. The prints, as a consequence, are entirely too contrasty.
If your developer cannot be kept at a temperature somewhere near 65 Fahr. in warm weather, reduce the amount of carbonate of soda, and your prints can be made to develop slowly and with proper gradation. It isn't the paper that is at fault - the emulsions have not become more contrasty - it's the manipulation that is wrong.
For the benefit of those who have been or may be troubled with yellow stains or toning spots, let's take up the subject of fixing baths for a moment.
If you get such spots you have a toning bath instead of a fixing bath. Sulphur has been released from the hypo in your bath and your prints have partly toned while fixing.
If prints have not been thoroughly washed, this toning may continue while prints are drying, or may not be noticed at all until the prints are on the drying racks.
Hypo is certainly less expensive than your loss of prints and the time in making them. Use a fresh Hypo bath - use the best chemicals in your bath and compound it carefully.
The Hypo is the agent which dissolves the free silver salts not acted upon by light. Hypo alone will fix a print, but a hardening solution is necessary to clear the print, prevent stains and harden the emulsion.
The hardening solution is mixed separately and added to the Hypo solution, and as this hardener may be made up in a stock solution, it becomes a very simple matter to mix a fresh Acid Fixing Bath.
The hardener is composed of water, Sulphite of Soda, No. 8.Baby days and baby ways are over all too soon.
A good picture, though, will keep the memory of those days fresh through all the years of growth and change.
When was your baby's picture last taken ?
There's a photographer in your town. Eastman Kodak Company, Rochester, N. Y.
Acetic Acid (28% pure) and Powdered Alum. The Acetic Acid is the clearing agent and clears both the bath and the prints. Without it the bath would be milky. And if it is used stronger than a 28% solution, the balance of the bath will be destroyed.
The Alum is used as a hardener.
The Sulphite of Soda is used to balance the bath by preventing the liberation of sulphur, which causes the toning action first mentioned. Any form of acid will attack Hypo and release sulphur, and as both acetic acid and alum are present, there must also be enough sulphite of soda to counteract the acid and prevent sul-phurization.
Old or weak sulphite of soda should be avoided, as the amount of sulphite given in the formula is just sufficient to prevent sul-phurization. E. K. Co. Tested Sodas are specified in the formula because of their uniform strength and purity. Be sure your sulphite is always kept in an airtight can or bottle, as it deteriorates when exposed to the air.
Never overwork your fixing bath, or you may expect trouble. An overworked fixing bath is as dangerous as an improperly mixed bath.
By knowing the action of your chemicals, and by keeping the above things in mind, you will be able to prevent troubles, the occurrence of which always mean
a loss to you, both in time and materials.
If you do not have the latest edition of "Artura Results," a postal will bring it to you, and the information it contains will always be found helpful.