Reducing Overdeveloped Negatives - Which Hypo to Use?

[Jarvman]

Hi all. I've overdeveloped some HP5+ in HC-110 by a stop (50% too long). I'm hoping to use Kodak R-4b negative reducer to cut the overdevelopment back.

The formula is

Sol A.
Pot. Ferri ... 7.5g
Water to make 1 litre

Sol B.
Sodium Thiosulphate 200g
water to make 1 litre

My question is, what effect will it have if I use an acid hypo for Sol. B instead of the plain hypo detailed in the formula above? I have some mixed up already. Considering plain hypo doesn't keep for longer than a day I want to use an acid hypo because of its keeping properties. Will this have any adverse effect on the negative reduction I wish to carry out? Cheers

[Ian Grant]

If you mean a rapid fixer when you say Acid Hypo then it's not a good idea as they contain Ammonium Thioslphate and bleaching would be very much faster and could give uneven results.

If you do use a Rapid fixer then it would need to be very dilute.

Ian

[Jarvman]

It's not rapid fixer Ian. The acid hypo is sodium thiosuphate with some metabisulphate added. It's a 2 bath procedure. The bleach is first, followed by re-fixing in hypo. Cheers

[John Austin]

Big problem with a ferricyanide reducer is that it will tend to remove proportionately more silver from the shadow areas than the highlights, which will exacerbate your problem

There are "super-proportional reducers" which will tend to make the neg' softer, which is what you want, but in my single experience the Ilford one can be uneven in use

My personal advice is to try printing on a soft grade of paper and if that does not work abandon the negs to experience - OK, Sod's law states that they will be the best thing you have done in ages, but that is the nature of life

If you can't find a formula for a super-proportional reducer PM me - It contains a strong oxidising agent, which means it can't be posted - Try the chemical supply houses in England, that goes for the hypo as well

[Ian Grant]

It's not rapid fixer Ian. The acid hypo is sodium thiosuphate with some metabisulphate added. It's a 2 bath procedure. The bleach is first, followed by re-fixing in hypo. Cheers

If that's the case any type of hypo or fixers OK. Some reducers like Farmers use the Ferricyanide in the hypo which has a short life once mixed.

Another option is to bleach the film in Ferricyanide/Potassium Bromide bleach, wash well expose to light and redevelop.

Ian

[Jarvman]

I hear what you're saying about the ferricyanide as removing more silver from the shadows. However, It states in the darkroom cookbook that R-4b reduces image density in proportion to silver deposited. Which means that it'll work on the highlights foremost. Strangely, Kodak R-4a (a cutting/subtractive reducer) works on the shadows and mid tones foremost. The only differences between these two formulas is the amount of pot. ferri used in Sol. A. Interestingly it would seem that the amount of pot. ferri in solution changes the nature of how the reduction works, not just its speed. The negs are still printable. I just gave one strip of film a dip in the reducing bath to see how things work.

[Gerald C Koch]

If the negatives are only overexxposed by 1 stop then just print through the extra density. No need to reduce them. Some photographers do this routinely for good shadow detail.