523. With the following formula there is little or no danger of fog from long development if the tank is covered, excluding: all light: -

Metol - Hydroquinone Tank Developer No. 2.

Metol .........................

........... 4 grains

Hydroquinone..................

........... 4 grains

Sulphite of Soda (anhydrous). . .

3/4 ounce

Carbonate of Soda (anhydrous) ..

1/2 ounce

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

........... 64 ounces

If crystal sodas are used, use twice the amount.

524. Unquestionably one of the best developers for long development, and one which will not fog, is glycine. This developer is prepared slightly different than when used for tray development. This is especially noted for the reason that if the ordinary glycine formula is used for many plates it will sometimes impart a yellowish tinge to the negative This is overcome in this formula by using not more than equal weight of sulphite to glycine, when preparing the solution.

GlyciniE Formula for Tank Development No. 3.

Water (hot)...................

7 ounces

Sulphite of Soda (anhydrous)...

30 grains

Carbonate of Soda (anhydrous). .

30 grains

Glycine

30 grains

After the above have been dissolved add water, twenty-eight ounces.

Note. - If crystal sodas are used, employ double the weight, or sixty grains in place of thirty grains.

525. In using any of the above developers in the tank it is advisable that the temperature be not more than sixty degrees Fahr., in order to obtain the best results. If the weather is very warm the tank should be placed in a vessel containing very cold water for a time, and in cold weather, when it is very cold, the tank should be placed in a vessel containing warm water, thus equalizing the temperature. These formulae for long development are not as reliable for exact time for complete development, but as there is so much latitude, by occasional examination the best results can be obtained from any exposure. For instance, if a normal exposure would develop in thirty minutes a very much under-timed plate could develop for an hour, or even all day, and improve with time. So when using the above formula, it is advisable to examine each plate in the tank before removing, and if any are not perfectly developed place them back into the tank until fully developed.

When using glycine developer special care should be exercised that no trace of hypo is conveyed to the developer or yellow stains will surely follow. For fixing use the regular acid-fixing bath.