Tell me about benzotriazole

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BetterSense

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I have a whole bunch of TMY that I got for cheap. It works; right now I shoot it at 200 and I get good results but you can really see the base fog. I understand that you can use benzotriazole or something like that to suppress base fog, but how does it work, and where can I get it?
 

Rlibersky

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Is the film fresh? How long are you developing it for? What are you developing it in? If the film is fresh I would look at your process before adding any antifoggant.

Randy
 

Muihlinn

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I've used a 2% solution, which I've mixed later with the developer (10ml by liter) to avoid base fog on way way past from expiry date stock (+10 years), and it works but has its price, like reducing the speed. If the stock is not that old, and you get good results, I won't add anything.
 
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BetterSense,

Just print through the base fog. Normally, this is the best solution.

If the film is quite old and the fogging interferes with the shadows, you can overexpose it a bit to get the shadow values up out of the fog (looks like you are already doing that to some extent shooting at EI200).

Being able to "really see the base fog" is not necessarily an indicator that the film is fogging more than normal. Have you compared it to new film processed the same way. Are you sure you have more fog than "normal" for your developer? Is something else fogging the film? Light strikes, etc.?

I have TMX from 1999 that is still going strong with no fogging to speak of.

And, to expand on the answers to your original question: benzotriazole is an organic anti-fog agent that is often used in place of or addition to potassium bromide. It has a tendency to cool print image tone a bit in comparison to bromide alone. I use a 2% mix like Muhilinn, and add it to print developers in increments of 10ml/l to "clear" the whites some. The effect is a very noticeable loss of speed.

The same would happen with film, I'm sure, so it is usually better to just overexpose a bit and forget the extra restrainer in the film developer. This, as mentioned already, puts the shadow values above the fb+f a bit more and probably results in more available film speed than adding benzotriazole.

Best and good luck

Doremus Scudder
www.DoremusScudder.com
 
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BetterSense

BetterSense

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The film expired in 2004; it looks foggy compared to fresh TriX and other films.
 

JBrunner

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As Doremus said, a generous exposure that allows you to disregard the base fog is easiest. All film developer combos have some level of base fog. As it increases (usually with the age of film) it doesn't become much of an issue until begins to change the values beyond what a minor contrast adjustment in printing gives. Most likely you can print right through it.
 

Muihlinn

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As Doremus said, a generous exposure that allows you to disregard the base fog is easiest.

As long as you're the one who is going to expose the film. In my case it was very old movie stock which was expired in around 1995, if not before that date with uncertain storage. All of it came from a late friend's state of in form of exposed rolls without much more information, in almost any other case I'd avoid to add antifogging, as I did with other films of him, just because you need a negative which prints beautifully, not a beautiful negative to the eye.
 
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