Development.—Best results are obtained with the temperature of the developer from 60° to 80° F. Immerse the print in the developer with a quick sweeping motion to prevent air bells. Develop in artificial or weak daylight. The development of a print from a normal negative will require 40 seconds or more.
Formula for Developer.—
| Water | 50 ounces |
| Neutral oxalate of potash | 8 ounces |
| Potassium phosphate (monobasic) | 1 ounce |
Care must be used to obtain the monobasic potassium phosphate.
Immediately after prints are developed, place them face down in the first acid bath, composed of
| Muriatic acid, C. P. | 1 ounce |
| Water | 60 ounces |
After remaining in this bath for a period of about 5 minutes, transfer to the second acid bath of the same strength. The prints should pass through at least 3 and preferably 4 acid baths, to remove all traces of iron that may remain in the pores of the paper.
When thoroughly cleared, the print should be washed from 10 to 20 minutes in running water. If running water is not available, several changes of water in the tray will be necessary.
“Water Tone” Platinum Paper.
Print by direct light (sunlight preferred) until the shadows are clearly outlined in a deep canary color. At this stage the same detail will be observed in the half tones that the finished print will show. For developing, use plain water, heated to 120° F. (which will be as hot as they can bear).