345. Filling The Developing Tank

Filling The Developing Tank. Prepare in a large graduate or pitcher the quantity of developer necessary to fill the size tank employed. With the tank loaded with plates, place on the cover, insert the funnel, and pour into the tank the proper amount of developer to completely cover the plates.

346. Note

Note. It is important that the full quantity of developer be contained in one vessel, and the flow into the tank must be continuous without any intermission; otherwise the finished negatives are liable to show streaks where the intermission took place. If a vessel large enough to hold the full quantity of developer cannot be had at the time, it will be necessary to fill the tank with the developer before inserting the plates. You thus avoid streaks. If the latter method is employed it is advisable, when placing the plates in the tank, to slowly raise the negative rack, or plate lifter containing plates, a few times up and down in the solution, but do not raise them above the solution. This will remove any air-bells that may collect on the films. Should they remain unbroken they would cause pin-holes and spots on the finished negative.

347. Developing

Developing. Where the developer is poured into the tank after the plates are inserted, as soon as the tank is full of developer note carefully the time at which the development will be completed. Do not disturb the plates until that time has arrived. When the tank is filled with devel-er first and the plates inserted afterwards, the time should not be taken until after you have raised and lowered the plates a few times, to remove air-bells.

348. Temperature

Temperature. It is important in automatic tank development that the temperature of the bath be between 65° and 70° Fahr. It must not be over 70°, for an increased temperature will quicken the developer, and a decreased temperature will retard it. The temperature of the developer should be tested with a thermometer just before the solution is poured into the tank. A change of 5° in temperature may lengthen or shorten the required time for complete development; thus the necessity of knowing the temperature just before you begin to develop.

349. Fixing Bath

Fixing Bath. The acid fixing bath is recommended for tank development, as it hardens the film, making the plates less liable to damage from handling. The regular prepared acid fixing powder, prepared in packages ready for use, will be found very convenient. All that is required is to dissolve the contents in a given amount of water and place in a jar or vessel ready for use. For those who prepare their own hypo bath we recommend the following:

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

30 ozs.

Hyposulphite of Soda.................

8 ozs.

Sulphite of Soda (Anhydrous)................

160 grs.

When fully dissolved add the following hardner:

Dissolve in 2 oz. of lukewarm water and then add to bath:

Stir well while adding the hardner. This bath should thoroughly fix plates in 15 minutes. The hypo bath may be used continuously, so long as it retains its strength or is not sufficiently discolored to stain the negatives.