8. Preparing A Small Bath

Preparing A Small Bath. As before stated, when albumen paper is not used exclusively and on a large scale, then there is no need for a stock solution and the bath may be prepared in a bottle, ready for use. Usually a 60-ounce bath is sufficient, and this is prepared as follows:

9. In a glass bottle containing 60 ounces of pure water, dissolve 6 ounces of nitrate of silver crystals. The crystals may be dissolved by shaking the bottle or by stirring with a glass rod. When all is dissolved test with the hydrometer. The bath should test between 55° and 60°. If the amount of silver added does not bring the bath up to this test, add more silver. If the bath tests over 60°, dilute by adding pure water. For general purposes the bath works best when testing between 55° and 60°.

10. In large studios where large quantities of paper are consumed, a reserve stock of solution is usually prepared, using a 2-gallon glass bottle and filling about two-thirds full with pure water, and then dissolving sufficient nitrate of silver to make the bath about 60 grains to the ounce. From this stock solution, the baths in use are replenished and kept up to their normal bulk and strength.

RESPONSIBILITY Study No. i  See Page 355 Katherine Bingham

RESPONSIBILITY Study No. i- See Page 355 Katherine Bingham.

11. Where a variety of negatives are to be printed from, some hard, some medium, others very soft, we usually provide two baths of different strength. The strong bath is used for sensitizing paper to be used on medium strength or very thin negatives, while the weaker bath is used for paper sensitized for hard negatives. The weak bath gives slow or deep printing, thus enabling high-lights to print with the shadows and thereby overcoming heavy bronzing of the densest shadows, which usually occurs when printing from hard, contrasty negatives. With thin, soft negatives, of equal strength throughout, the printing is quicker, and if the paper is weak in silver the deposit will be insufficient to hold up the image, with the result that the prints are weak and mealy looking. With the stronger bath, which makes the paper richer in silver, you have a heavier deposit, permitting of deeper printing, resulting in stronger prints; hence the object of the different strength baths.

12. Neutralizing The Bath For Use

Neutralizing The Bath For Use. A silver bath for sensitizing paper should always be kept neutral or slightly alkaline, which is just the opposite for sensitizing plates. For the latter the bath must be acid. An acid printing bath will give poor, flat prints, while a slightly alkaline bath will give rich, strong prints. The bath when freshly prepared and tested with blue and red litmus paper, will usually be found to test slightly acid, the blue paper turning slightly red. To neutralize it, or to make it slightly alkaline, as is required, add to this bath a few drops at a time of aqua ammonia, stirring the bath each time and testing with the red litmus paper. When the red litmus paper turns slightly blue it is in proper condition and ready for use.