Developing Dry Plates and Developing Plates with the Eastman Plate Tank – How to Make Good Pictures

Plate tanks are relatively easy to find on ebay or from some of our favorite sellers like Pacific Rim Camera. I've seen a number of proud new owners posting photos of their tanks in various collectors groups. I thought it might be helpful to repost the following article describing how to develop using the Eastman Plate Tank. This is taken from a 1910s copy of Kodak's How to make Good Pictures, an excellent book which I was fortunate enough to buy at an specialty shop in Oregon, Shadowsmith Photographics. 

Developing Dry Plates & Developing Plates with the Eastman Plate Tank

from How to Make Good Pictures


The foregoing directions apply to dry plates as well as the chemical treatment being the same, except that the preliminary wetting may be omitted with plates.

Plates, however, must be handled in the solutions one at a time as they would scratch each other if a larger number were put into the trays simultaneously. They should also be developed film-face up.

NOTE–Plates should be developed to the same density as film negatives and may be examined, while developing, before the dark room lamp in the same manner.

For fixing plates it is best to procure a fixing box, which is arranged with a set usually of twelve grooves. Each plate may thus be dropped into a groove for fixing, thus eliminating the danger of scratching or overlapping.

In washing plates, be careful that they do not overlap or touch each other, owing to the likelihood of the corners scratching the emulsion.

After the negatives have been thoroughly washed they must be dried.

Plates should be placed in a drying rack and kept in a cool place until dry. They are then ready for printing.


The Plate Tank is the same in theory as the Kodak Film Tank, with, of course, such modifications as are rendered necessary by the physical difference between plates and film. The Eastman Plate Tank consists of a metal solution cup with tightly fitting cover, a cage for holding twelve plates, or less, during development and an ingenious loading fixture for loading plates into the cage in the dark-room.

The exposed plates are loaded into the cage and placed in the tank in the dark-room, and the tank cover fastened in place. On the front of the tank is a dial for registering time. Development is allowed to continue for fifteen minutes, the tank being reversed several times. After development the developer is washed from the plates, the cage removed from the tank in subdued light, and the plates placed in fixing bath. After fixing the plates are ready for washing in the usual manner.

The Developer:
We recommend the use of Pyro. The Kodak Tank Developer Powders are prepared for use with the Eastman Plate Tank and are made from carefully selected and tested chemicals.

For the 4 x 5 Eastman Plate Tank, use a "2 and 3½ Inch" Kodak Tank Developer Powder and for the 5 x7 Tank, use a 5x7 Plate Tank Developer Powder.

What Developer to Use for Dark-Room Development: 
It is well not to try too many developers at the beginning. To understand one thoroughly, or at the most two, will give you results from which you will obtain more satisfaction than should you dabble with the various formula on the market to-day. Thoroughly master one before trying others. One may start with "Pyro" or "Hydrochinon", which are without doubt two of the best.

Pyro the most popular has a decided tendency to stain the fingers. Should this be objected to, Hydrochinon in connection with Elon (which is free from that objection) can be used with good results. Not every photographic beginner owns a pair of chemist's scales, which are a necessity should he wish to compound the formula himself. Rather than be uncertain as to correctness we would advise the use of developing powders. Eastman Special Developer Powders are particularly desirable as they do not stain the fingers. If, however, the amateur desires to mix his own developer, the following stock solutions used as below will be found excellent developers for the dark-room.
Pyro Solution.
"A" ––/–– Avoirdupois.
Pyro, – – – – – 1 oz.
Sulphuric Acid,  – – – – – 20 minims.
Water,  – – – – – 28 ozs.

Soda Solution.
"B" ––/–– Avoirdupois.
E. K. Co. Carbonate Soda (desiccated*), – – – – – 2 ozs.
E. K. Co. Sulphite Soda (desiccated*),  – – – – – 3 ozs.
Water,  – – – – – 28 ozs.

For Dark-Room Development Take
"A– – – – – ½ oz.
"B– – – – – ½ oz.
Water– – – – – 4 ozs.

This developer will then contain 1.56 grains Pyro per ounce.

Solution A.
"A" ––/–– Avoirdupois.
Elon, – – – – – 60 grains
Hydrochinon,  – – – – – 30 grains
E. K. Co. Sulphite of Soda (desiccated),  – – – – – 3/4 oz.
Water,  – – – – – 20 ozs.

Solution B.
"B" ––/–– Avoirdupois.
E. K. Co. Carbonate of Soda (desiccated*), – – – – – ½ oz.
Water,  – – – – – 280 ozs.

*If other brands of desiccated Carbonate of Soda are used a greater quantity will be required. If crystal sodas are used, take about three times the quantity of Carbonate and double the quantity of Sulphite.

To Develop:
Take Solution A 1 oz, Solution B 1 oz, Water 2 ozs. Add one or two drops of a 10 per cent. solution Potassium Bromide to each ounce of developer. 

NOTE–By making a comparison between the developing solutions used in the developing Tanks with those in use for dark room development, Sulphite of Soda is in excess. The reason for this is that, owing to oxidation when exposed to the air as in dark-room development, the Sulphite of Soda is necessary to prevent the negatives becoming too yellow. By the tank method we may use a minimum of sulphite as the negatives are not subject to this fault.

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