Benzotriazole and Contrast

[Matthew Gorringe]

In a number of threads and other correspondence I have seen people making comments indicating that they lose contrast as they add Benzotriazole to their paper developers.

This is completely the opposite of my experience with Galerie and Emaks in Dektol and Ansco 130. I find that as I add BTAZ I need to compensate with increased exposure times and see a marked increase in the contrast of my prints. The increased exposure is needed to keep detail in the highlights and results in significantly darker shadows.

My limited understanding of what's happening here is that the restraining action of BTAZ has a greater effect in areas of low print density (highlights) compared to areas of greater density (shadows). It seems to me that the effect is to reduce to initial speed of the paper, or to push the paper's toe to the right of the response curve but not so much the shoulder or straight line section. This would lead to a steeper curve and therefore higher overall contrast. Of course this effect would also explain why BTAZ is able to rescue fogged papers.

If you're one of the people who sees a reduction in contrast; do you add enough BTAZ to require an adjustment in exposure time? Do you compensate by increasing development time? Am I misinterpreting what I see?

 

[Mike Té]

Interesting question, Matt. I look forward to some comments as well.

 

[Dan Henderson]

I occasionally use BZ to cool off print tones. The first time I used it I noticed that the print did not start to come up in the developer as soon as it did before adding BZ, and appeared weak and underdeveloped at my usual developing time of 2:30. So I may have increased exposure time (don't remember for sure, but since then I add the BZ to my developer as soon as I make it up and develop my test strips in it), but more importantly, I increased development time to 3:00 and get good strong print tones now.

 

[eclarke]

I use 15 cc 1% benzotriazole per 1L of 130 developer and leave out the bromide. I also increase the carbonate to 80g. anhydrous/L. It appears to be the best formula for the papers I use...EC

 

[Lowell Huff]

Be careful when adding restrainers to formulas. BZT restrains the shoulder and Bromide, the toe. If you take the standard film curve and rotate it 90° clockwise, you will see the progression of development of paper. The toe comes up first and then the mid tones and finally the shoulder.

 

[PVia]

...and which papers do you use?

 

[eclarke]

Sorry, My go to is Ilford WT FB. This cool formula takes the warmtone to just a hint past neutral and selenium tones well. I also print Ilford MGIV FB neutral and Oriental FB neutral, all glossy...Evan Clarke

 

[Matthew Gorringe]

Sorry, My go to is Ilford WT FB. This cool formula takes the warmtone to just a hint past neutral and selenium tones well. I also print Ilford MGIV FB neutral and Oriental FB neutral, all glossy...Evan Clarke

And if you add more BTAZ do you see the contrast of the paper increase or decrease?

 

[dancqu]

Patrick Dignan states that BTAZ is similar to bromide in
it's action; holds back density build up in the little exposed
areas more so than in the much exposed areas. So, an
increase in contrast.

By way of contrast, David Kachel has, for a reduction in
contrast, suggested the addition of potassium ferricyanide
to the developer. A technique I intend to try.

For details search this NG for Kachel. David is known for
his work with and development of the SLIMT. Dan

 

[Matthew Gorringe]

Patrick Dignan states that BTAZ is similar to bromide in
it's action; holds back density build up in the little exposed
areas more so than in the much exposed areas. So, an
increase in contrast.

By way of contrast, David Kachel has, for a reduction in
contrast, suggested the addition of potassium ferricyanide
to the developer. A technique I intend to try.

For details search this NG for Kachel. David is known for
his work with and development of the SLIMT. Dan

Yes I downloaded every article on David's site about 4 months ago, extremely valuable stuff there. I've got a couple of prints where it might be worth trying latent image bleaching so maybe I should have a go too.

 

[eclarke]

And if you add more BTAZ do you see the contrast of the paper increase or decrease?

The prints get a little muddier and the developer loses activity. Adding benzotriazole to the bromide in 130 is a lot of restrainer= loss of activity...EC

 

[eclarke]

Yes I downloaded every article on David's site about 4 months ago, extremely valuable stuff there. I've got a couple of prints where it might be worth trying latent image bleaching so maybe I should have a go too.

The latent image bleaching really works for paper and for film. I pre bleach negatives in my Jobo routinely because it's so easy....EC

 

[eclarke]

My variation on 130:


Water (125 degrees F) . . . . . . . . . . . . . 750 ml
Metol . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 g
Sodium Sulfite (Anhydrous) . . . . . . . . . 50 g
Hydroquinone . . . . . . . . . . . . . . . . . . . . . 11 g
Sodium Carbonate (Anhydrous) . . . . . 80 g
1% benzotriazole solution. . . . . . . . . . . . . . . 15 cc
Glycin . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 g
Cold Water to make . . . . . . . . . . . . . . . . 1 liter

Dilute 1+3 and it likes 73 degrees in the tray...Evan Clarke