310. The plate-glass is recommended where a brilliant surface is desired. The opal, or ground-glass, is recommended for very fine grain matt surface results.

311. Preparing The Opal Or Ground-Glass

Preparing The Opal Or Ground-Glass. The opal, or ground-glass, has an advantage over the plate or transparent glass, from the fact that the development can be watched and examined, while on the latter the development is more difficult. If, however, a white porcelain tray is used, the development can be watched on plain glass just as well.

312. Cleaning The Glass

Cleaning The Glass. The plate used for this purpose must be perfectly clear and clean. In order to insure clean plates we advise placing them in a carbonate potash bath, made as follows:

Water........................................

32

ozs.

Carbonate of Potash .............................

6

ozs.

313. Place this bath in a porcelain tray and immerse the plates for about three hours. If these plates have been previously used, they must remain in the carbonate potash bath until the wax is thoroughly dissolved. They should then be rubbed with a piece of flannel and finally rinsed in clean water, then placed in a rack to dry.

314. Waxing The Glass

Waxing The Glass. After the plates are thoroughly cleansed they must be prepared with a waxing solution, as follows:

Beeswax ..........................................

20

grs.

Pure Benzole ........................................

4

ozs.

315. In order to dissolve the wax more quickly, it is advisable to warm the benzole. To do this, place the benzole and wax in a glass bottle and stand in a kettle of hot water. It will be necessary to renew the hot water from time to time. You must be careful and not place near a stove or light of any kind, as the benzole is very inflammable and explosive, but there is no danger if you keep it away from fire. After the wax is dissolved it should be filtered and the clear solution used when preparing the plates.

316. Applying Wax Solution To The Opal, Ground-Glass Or Plate Glass

Applying Wax Solution To The Opal, Ground-Glass Or Plate Glass. After you have carefully polished the surface of the plate it is intended to use, place it on a table, which is free from dampness and dust, and with a piece of flannel soaked with a small quantity of waxing solution, rub over the surface of the glass very quickly. Avoid going over the same spot twice, as this would give you an uneven waxing and also too much of it. Any number of plates may be prepared in this way and placed in a rack to dry. The drying requires about half to three quarters of an hour.