3. Open one of the developer pow ders, then put the contents, (two chem icals) into the beaker and pour in four ounces of water. Stir until dissolved with the stirring rod, and pour into second tray.
4. Take one of the exposures from the water and immerse it, face down, in the second tray. Rock it back and forth to prevent streaks and air bubbles ; in about one minute the film will begin to darken in spots, representing the lights of the pidure, and in about two minutes the operator will be able to distinguish objeas in the piaure. The developer should be allowed to ael five to ten minutes.
5. Transfer the developed film to the third tray, and rinse two or three times with water, leaving it to soak while the next film is being developed.
NorE.—Fiye or six 4 x 5 negatives can be developed, one after the other, in nne portion of devel oper, made by use of Eastman's Special Developer PoN\clers, then it should be tht own away and a fresh portion mixed.
Only one negative should be developed at a time until the operator becomes expert.
As each successive negative is developed, it should be put, with the preceding negatives, in the washing tray, and the water changed twice, to prevent the developer remaining in the films from staining them.
6. Prepare in the fourth tray sufficient fixing bath to fully cover the negatives, use ounce of Kodak Acid Fixing Powder to each 4 ounces of water.
7. Immerse the negatives one by one in the fixing bath until they are entirely clear of white spots and are transparent instead of milky by trans mitted light. This will require about ten minutes.
S. The yellow shade can be removed from the lamp as soon as all the exposures have been fixed.
Wash and dry as per directions on page So.
The fixing solution must only be used in tray No. 4, and the negatives, after fixing, must not be put in either No. or No. 2 trays. Neither must any of the fixing solution be allowed to touch the films, through the agency of the fingers, or otherwise, until they are ready to go into the fixing bath, otherwise, they will be spotted or blackened, so as to be useless, The trays and beaker should now be rinsed out and set away to drain and dry.
The foregoing pages fully cover the subject of development so far as telling the beginner exactly what to do is concerned. If the amateur fol lows absolutely the directions therein given he will secure good results ; but a word of the theory of development will nevertheless prove interesting and instructive.
An exposed and unexposed film do not differ, so far as the eye can judge. It is necessary, therefore, to treat the exposed film with a solution containing certain chemicals to reveal the action of the sun's rays.
This is called development.
The chemicals are the developer.
The active or developing agent, such as Pyrogallic acid (commonly known as Pyro) and Hydrochinon, affect the latent image by reducing to metallic silver those parts which have been affected by the light. In other words, it blackens them. But these agents require the use of another sub stance to give them energy: An alkali when mixed with the active developing agent gives it a greater affinity for oxygen; it therefore becomes more energetic as a reducer. This alkali is called an accelerator. The alkalies most commonly used are Carbonate of Soda (known as sal soda and washing soda) and Carbonate of Potassium.
A restrainer is a substance that has the power to restrain or retard the action of development. Bromide of Potassium, most commonly used for that purpose, has the property of dissolving a certain amount of Bromide of Silver from the film, thereby forming a double salt which is less easily reduced by the developer. This action having taken place, the develop ment is much slower; hence the name, "restrainer." The preservative is a substance that will keep the developer from discoloring and oxydizing when it is to be kept for future use. " Sulphite of Soda " is most commonly used for that purpose; it also has much to do with the color of the negative. If only a very small portion be used the negative will be brown, the quality being harsh and hard and one that will give you a print of much contrast, while the use of a greater portion gives a gray, soft negative with more detail.
The fixing or clearing of a negative is due to the action of the " Hypo sulphite of Soda " eating out the Bromide of Silver not acted upon by the light, and until this has been accomplished it is still sensitive. When the creamy appearance on the back of the negative disappears it may be called " fixed," and can then be taken from the bath and exposed to any light without fear of injury.