1% Benzotriazole + Expired Film

Attachment shows effect of adding 1% Benzotriazole solution to 20 year old T-Max 400 all exposed at EI=100 and developed in PaRodinal 1:50 8min 20C.
What is a good combination of ml/L 1% Benzotriazole and increase in development time?
10ml/L and 30% increase?
Thanks.

What volume of developer did you use? 10ml added to 220ml gives a different concentration than 10ml added to 1000ml.

The amount is listed below each strip as ml of 1% per Liter.

Yes, it's ml of 1% Benzotriazole per liter of developer, thanks, I edited it in the OP.

The 1% solution was made by dissolving 1g Benzotriazole in 30 ml Isopropyl alcohol (dissolves easily) and making up to 100ml with water.

Background fog, especially with negative film and at these low levels, is no show stopper. Can you see to which extent shadow detail suffers at the higher BTAZ levels?

I have the impression that at 10 ml/L 1% BZT the fog goes but all the shadow detail stays but IDK if that is theoretically possible.

Alan Johnson: I do not think that you can have your cake and eat it also: with the fog, also goes the shadow detail. Expose more. Read:

You have to remember that when using restrainers, the film speed drops. Think of it this way: age-fog is in the same category as the toe on the characteristic curve. Thus, emergent shadow detail becomes the target of suppression, as does the fog, itself. That is why routinely adding restrainer to developers can be self-defeating with fresh film. The negative's base will look great, but the speed (thus shadow detail) will be compromised. The ONLY way to separate such emergent shadow detail is to elevate that shadow detail upon the characteristic curve.

That said, old, foggy film needs this restrainer boost. If, ultimately, you can use such film, productively, and not have to throw it out, who cares if the speed drops? Here is what I do. I cannot prove that this is theoretically valid but, for me, it WORKS.

First, take either one gram of benzotriazole OR 18 grams of potassium bromide. Put that in 250ml of water. I put the water and chemical in a small, PET plastic bottle, cap it, and shake vigorously for a few minutes. THAT dissolves the BZ completely, (The PB, if you used that instead, is far easier to dissolve.) I have never used alcohol but that might also be a way to do it. To this, I add a little sodium bicarbonate: about 12 grams. That dissolves rather quickly after a minute of shaking.

This is your restrainer stock, which I will call RS. I use the designation 'RSL' to indicate the amount of this RS i will add to each liter of developer working solution for film. I find that adding about 50 ml per liter is excellent with highly diluted developers such as D-76 1+3. The sodium bicarbonate slows things down (so fog is kept low) and I honestly believe that that baking soda aids the restrainer in its work. I have some Kodak 2484 film that is so fogged that anyone would discard it, but with this, I have no problem as long as I expose at about EI 16. You might have to add a bit of sodium carbonate if development gets too slow, but not much, maybe start with 1 gram per liter of developer working solution, and go from there.

The development time is tricky: you want adequate contrast (usually you will have to put up with a gamma of about 0.6) and still keep the fog low. Make clip tests, using only about one exposed frame, but I use highly diluted developers and the extra exposure kind of makes up for the reduction in develper energy. Try, at first, about the same normal development time.

Think of the needed extra exposure in this way; for such fogged film and development, the exposure must START about halfway up the characteristic curve, because, with such film, the first half is now fog. Thus, with really old, (formerly fast,) film, the highlights might get squeezed a bit, but you will be amazed how the film's latitude can save the day here.

For PAPER, I find that I can use the same RS but with far more (maybe up to ten times as much) baking soda added. This, for me, works wonders at times with bad paper: The baking soda slows development and seems to synergize with the restrainer in order to truly suppress fog. (Please do not ask me to post examples, as that is not feasible right now, but testing what I say with only small amounts of solution should not be too trying for you.) Start with Dektol diluted a bit more, maybe 1 + 3 and go from there. Bottom line: use a coin test and make certain that the unexposed area under that coin is not acquiring more than 50% density by the time you have finished developing the paper. Expose the image in order to get a full, dense picture. After fixation, use Farmer's Reducer to 'bring back' that coin area to whiteness. Now, that really dense image should be really good if you exposed properly. It will take much trial and error, but remember that the coin area must be pure white when you have finished with the Farmer's Reducer. This data will give you what you need to make further prints without the coin. Remember, the density under that coin determines your development time. The density of the print after that coin area becomes pure white, determines your exposure time. (Now you can see how lazy we become with fresh paper that cannot easily be overdeveloped!!!)

NB: if you do not have a scale, I do not know how you will measure the benzotriazole, as it is like 'feathers'. But to measure potassium bromide in milliliters simply measure 12ml (to equate to 18 grams). For baking soda, the volume needed is about 9ml (to equate to 12 grams). - David Lyga

Thank you, David,
I note you use 50ml of 0.4% Benzotriazole solution (with other additive) which is equivalent to 20 ml/L 1% Benzotriazole solution in my attachment series.It can be seen that this would reduce the fog more than the figure of 10ml/L 1% Benzotriazole I first mentioned.

Yea, do your own calculations according to what you usually use, Alan. I have done countless experiments and this is my data, but such data can easily be transcribed. My data is not the Holy Grail, but it might be highly relevant, nevertheless.

Remember, my data is for HIGH age fog, not light or medium. Measure accordingly, perhaps using only half my data for light to medium age fog. For some reason, Farmer's Reducer (FR) makes BW negatives lose MUCH contrast, so that is why I raely use FR with film. But with paper, the FR makes the contrast a bit bolder. That is usually very attractive. - David Lyga

Michael R 1974 said:

Alan, do you have Richard Henry's book? He did some interesting tests with age-fogged film and restrainers.

Click to expand...

Thanks Michael,
I looked in "Controls in Black and White Photography"
p188 He developed 4 years out of date Tri-X Pan in D76 1+1 with the equivalent of about 3 ml/L of 1% Benzotriazole solution on my attachment.He concluded that with film it will print just as well without Benzotriazole but noted that eventually a fog level will be reached where this is no longer true.
He did not investigate film that was more out of date than 4 years.

Old films with 1% Benzotriazole addition seem to need longer development.
I developed FP4 (discontinued in favor of FP4+ in 1990, date year of my film not known) exposed at EI=50 in Xtol 1+1 with 20ml/liter 1% Benzotriazole addition.
Double the normal time of development (from the massive development chart) was needed to give normal density and a good result.

I have an incentive to check this as was given a box of 60 HP5+ dated 2002 stored at 60-80F.
As its speed will have dropped I push processed it thereby hoping to restore it to box speed. Developer was Xtol 1+2.
The attachment shows the result without and with Benzotriazole addition.
The "without BZT" is more fogged but has more shadow detail. I obtained a good print from it, in spite of the fog.
So it seems best to omit BZT in this case, when wanting to push process to shoot at box speed.

The problem with using BZT with old film is that while is may decrease the amount of fog it also decreases the density of the negative. What Dr Henry found is consistent with this and also finds that it really is not needed. Since age fog is even throughout the negative you can just print-thru it.