When the plate is quite cleared, of which it is better to make sure by leaving the plate in the fixing solution for fully five minutes after it first appears clear, remove it and wash again very thoroughly, and then immerse it in the clearing solution.
| Water | 20 ounces. |
| Sulphuric acid | ½ |
| Alum | 2 |
Leave the plate in the clearing solution two minutes or more, then wash again, rubbing the surface lightly with a tuft of cotton to remove any sediment that may adhere to the film, then set it up in a rack to dry.
PORCELAIN AND OPAL TRANSPARENCIES
may be developed in the same manner until detail may be seen in the face, if it is a portrait; then remove it and instantly flow with a solution of bromide of ammonium to stop developing action, then wash, fix and dry as before.
For portraits on porcelain or opal, to be viewed as positives by reflected light, develop until the fine half-tones in the face are visible. When they are for transparencies, p217 either for window or lamp shades, develop until the detail in the high lights of portrait or landscape are well out. This may necessitate a longer exposure by lamp-light.
Transparencies developed by other methods receive a stain or color, which, in many cases, is not unpleasing; for instance, the following formula will give a very beautiful yellowish color:
| Saturated solution yellow prussiate of potash, | 4 ounces. |
| Pyro | 2 grains. |
| Ammonia (conc.) | 2 drops. |
This will cover and develop one 8×10 plate, giving it an agreeable color similar to that produced by development by sal soda and pyro, but much more agreeable.
A very fine blue color is imparted to the plate when developed by the following formula: