Maine-iac
Member
Several people have inquired about the divided developer printing method I use.
First, some general remarks: Divided developing is not a new idea. I ran across it first about 25 years ago in an old Dignan booklet of formulas, and have used it ever since. The concept is simple: by separating the activating agent from the developing agents into two separate baths, several things are accomplished:
1. Time/temperature considerations virtually disappear. Since no image appears in the developing agent bath (Bath A), any temperature will do. I've tested at temps ranging from 50F to 100F with no discernible difference. I've even had Bath A at room temp and Bath B 50 degrees warmer and everything was fine. Just came up faster in Bath B. Your ambient darkroom temperature will do just fine. All that happens in Bath A is that the latent image created by exposure under the enlarger absorbs the amount of developer it will need to fully convert the silver ions. As a result, Bath A never becomes exhausted; it only get used up physically in volume as each sheet of paper absorbs a tiny amount. It can be re-used indefinitely. Generally, about 20-30 sec. in Bath A is sufficient for the absorption to take place.
2. Since no actual image appears in Bath A, and in Bath B, only the absorbed developer is activated, one cannot over- or under-develop as long as sufficient time is given for absorption of the solution. Any density changes will have to occur under the enlarger, thus making you become a better printer.
3. Contrast is automatically controlled. You cannot increase or decrease contrast by leaving it in the soup longer or pulling it out sooner. You can leave it in Bath B all day and it will develop no further than what the absorbed developer from Bath A permits. Again, learn to control contrast under the enlarger. EXCEPTION: by using a soft contrast developer formula for Bath A instead of the harder formula, you can decrease contrast approx. 1 paper grade.
4. 2 liters of Bath B, which is just sodium carbonate (Arm & Hammer Washing soda) will process approximately 35-40 8 X 10's before beginning to become exhausted (weak blacks, muddy grays). Just discard and replace, at a cost of mere pennies. While the image can't over-develop, it can under-develop if you pull it too soon. At a normal ambient temp of around 70 degrees, it usually takes about 45 seconds to fully develop. The warmer your developer or room temperature, the shorter time it will take. I've never had it take longer than 45 seconds, even with a weakened solution. So the total time saving per print is considerable.
5. Bath A will keep more or less indefinitely, because the preservative is in it, but not the activator. Don't contaminate Bath A with Bath B or you turn it into a weak single-solution developer and all bets are off. In actual fact, I've kept it going for as long as 9 months without noticing any degradation. Once I had to stop printing for nearly a year, and the solution did go bad during that period. So figure on a 6-9 month shelf life before mixing fresh (again, at very low cost).
This method also works well with Ilfochromes (eliminates the temp control problems and naturally controls contrast) though with a different Bath A formula. Another topic for another day.
Caveat: I am not a chemist (Ph.D. in biblical studies and early Christian origins--- an almost totally useless field of knowledge---which along with $3 will buy me a cup of coffee almost anywhere), and my quantities, arrived at through experimentation, work, but are not necessarily the optimum in terms of interactions and proportionality. I'm sure Pat Gainer or others with more knowledge of chemistry can tweak them to be more correct. Here are the formulas I've been using for years quite successfully:
Normal-hard Bath A to make 2 liters
2 teaspoons Metol
3 Tablespoons Sodium Sulfite
2 teaspoons Hydroquinone
1/4 teaspoon Potassium Bromide
OR
10 ml Benzotriazole (not both)
Soft Bath A
2 Tablespoons Metol
3 Tablespoons Sodium Sulfite
1/4 teaspoon Potassium Bromide
OR
10 ml Benzotriazole (not both)
Bath B
2 liters water
1/2 cup sodium carbonate
No water rinse or stop bath between Bath A and Bath B.
I've also tried E-72 which is a Phenidone, Vitamin C formula for Bath A, but find that with the divided development technique, an extra boost is needed, so I add a teaspoon or two of Hydroquinone to the Phenidone, Vitamin C for Bath A, and that does the trick.
Larry Kalajainen
First, some general remarks: Divided developing is not a new idea. I ran across it first about 25 years ago in an old Dignan booklet of formulas, and have used it ever since. The concept is simple: by separating the activating agent from the developing agents into two separate baths, several things are accomplished:
1. Time/temperature considerations virtually disappear. Since no image appears in the developing agent bath (Bath A), any temperature will do. I've tested at temps ranging from 50F to 100F with no discernible difference. I've even had Bath A at room temp and Bath B 50 degrees warmer and everything was fine. Just came up faster in Bath B. Your ambient darkroom temperature will do just fine. All that happens in Bath A is that the latent image created by exposure under the enlarger absorbs the amount of developer it will need to fully convert the silver ions. As a result, Bath A never becomes exhausted; it only get used up physically in volume as each sheet of paper absorbs a tiny amount. It can be re-used indefinitely. Generally, about 20-30 sec. in Bath A is sufficient for the absorption to take place.
2. Since no actual image appears in Bath A, and in Bath B, only the absorbed developer is activated, one cannot over- or under-develop as long as sufficient time is given for absorption of the solution. Any density changes will have to occur under the enlarger, thus making you become a better printer.
3. Contrast is automatically controlled. You cannot increase or decrease contrast by leaving it in the soup longer or pulling it out sooner. You can leave it in Bath B all day and it will develop no further than what the absorbed developer from Bath A permits. Again, learn to control contrast under the enlarger. EXCEPTION: by using a soft contrast developer formula for Bath A instead of the harder formula, you can decrease contrast approx. 1 paper grade.
4. 2 liters of Bath B, which is just sodium carbonate (Arm & Hammer Washing soda) will process approximately 35-40 8 X 10's before beginning to become exhausted (weak blacks, muddy grays). Just discard and replace, at a cost of mere pennies. While the image can't over-develop, it can under-develop if you pull it too soon. At a normal ambient temp of around 70 degrees, it usually takes about 45 seconds to fully develop. The warmer your developer or room temperature, the shorter time it will take. I've never had it take longer than 45 seconds, even with a weakened solution. So the total time saving per print is considerable.
5. Bath A will keep more or less indefinitely, because the preservative is in it, but not the activator. Don't contaminate Bath A with Bath B or you turn it into a weak single-solution developer and all bets are off. In actual fact, I've kept it going for as long as 9 months without noticing any degradation. Once I had to stop printing for nearly a year, and the solution did go bad during that period. So figure on a 6-9 month shelf life before mixing fresh (again, at very low cost).
This method also works well with Ilfochromes (eliminates the temp control problems and naturally controls contrast) though with a different Bath A formula. Another topic for another day.
Caveat: I am not a chemist (Ph.D. in biblical studies and early Christian origins--- an almost totally useless field of knowledge---which along with $3 will buy me a cup of coffee almost anywhere), and my quantities, arrived at through experimentation, work, but are not necessarily the optimum in terms of interactions and proportionality. I'm sure Pat Gainer or others with more knowledge of chemistry can tweak them to be more correct. Here are the formulas I've been using for years quite successfully:
Normal-hard Bath A to make 2 liters
2 teaspoons Metol
3 Tablespoons Sodium Sulfite
2 teaspoons Hydroquinone
1/4 teaspoon Potassium Bromide
OR
10 ml Benzotriazole (not both)
Soft Bath A
2 Tablespoons Metol
3 Tablespoons Sodium Sulfite
1/4 teaspoon Potassium Bromide
OR
10 ml Benzotriazole (not both)
Bath B
2 liters water
1/2 cup sodium carbonate
No water rinse or stop bath between Bath A and Bath B.
I've also tried E-72 which is a Phenidone, Vitamin C formula for Bath A, but find that with the divided development technique, an extra boost is needed, so I add a teaspoon or two of Hydroquinone to the Phenidone, Vitamin C for Bath A, and that does the trick.
Larry Kalajainen