Benzotriazole

Hi all:

I'm going into the darkroom Monday and will be mixing Ansco 130 but with no bromide, substituted entirely with Benzotriazole. What is a good starting quantity to clear the highlights while keeping highlight detail in the print? 10ml of 2% solution or .2grams? less?

Any drawbacks to using benzo instead of bromide that I may not be aware of? I'm going for cool to neutral tones.

Also, what is the keeping property of benzo, I have plenty here, but it's nowhere between 18 months and 3 years old, I don't know.

Thanks!

Jarin

I use 15cc of 1% per liter of stock, no bromide.
As far as storing goes, I double bag the bottle and store it in the freezer. I've not had it go bad so I can't tell you when it will go bad.

The rule of thumb is to use 1/10 the amount of benzotriazole as bromide. This will provide the same restraining action. Benzotriazole is best used as a 1% solution. It is difficult to dissolve in cold water but will dissolve in hot water. This chemical is quite stable and the resulting solution should last for at least a year.

A caution about cold tone developers. There is a well known optical illusion whereby warm tones appear to be above the paper surface whereas cold tones appear to be beneath the surface. This is caused by the fact that the eye is a simple lens which cannot focus on colors from both ends of the spectrum at the same time. If the image tone is too cool it can give the print an ugly veiled appearance. It best to add the BZT slowly until the desired tone is achieved. As Michael points out bromide is released from papers when they are developed. For this reason some people find that they get better results by not completely eliminating the bromide. The image tone remains more constant over the useful life of the working developer.

Jarin,

I would take the informed advice of both Michael R and Gerald before mine. I will be switching my use to theirs.

So, in theory, one should use .55g of benzo / liter to give the same restraining as 5.5g Pot. Bromide, not the aforementioned .2 grams? I have KBr around too from last year, so I may consider putting in a trace base for a bit more consistency. I'm not stingy with quantity of developer per tray, though.

Does the use of restrainer effectively straighten the toe (highlights) of the paper? I'll be printing Pyro negs (WD2D+) on VC paper and wonder if this is a method I can use to reduce the compensation/flattening of the highlights that can supposedly happen with pyro negs and VC paper, if the highlights look too flat?

My benzo is still in dry form, probably from early 2013. Reckon it's still effective?

Jarin

I have some BZT that is going on 50 years. Probably older than many of those on APUG. Still works fine.

I use BZT as a copper corrosion inhibitor in the formulations that I make for work. What does BZT do in a photographic formula?

RattyMouse said:

I use BZT as a copper corrosion inhibitor in the formulations that I make for work. What does BZT do in a photographic formula?

Click to expand...

It's a restrainer/anti-foggant. In a print developer, it keeps the highlights white.