substituting Kbr with benzotriazole?

[phritz phantom]

i'm trying to mix a paper developer from scratch. to get a cold tone developer one can substitute potassium bromide with benzotriazole, so i've heard (read on this board). is this possible with all paper developer formulas that contain potassium bromide?
and how much benzotriazole should be added? the same amount as potassium bromide? or is it a more or less active ingredient?

thanks.
pp

 

[Roger Hicks]

i'm trying to mix a paper developer from scratch. to get a cold tone developer one can substitute potassium bromide with benzotriazole, so i've heard (read on this board). is this possible with all paper developer formulas that contain potassium bromide?
and how much benzotriazole should be added? the same amount as potassium bromide? or is it a more or less active ingredient?

thanks.
pp

VASTLY more active. Both slow dev times as well, of course.

Before you start trying to do this sort of thing I'd suggest you read one of the standard works on photographic chemistry -- Haist, Glafkides, Neblette, Clerc... Otherwise you really can't have enough of an idea of what you're doing.

I'm not being rude: I have read these books, and I still wouldn't have the confidence to try this sort of thing, which (as practised by most amateurs) is very hit and miss. A lot of people think they're being clever when in reality their screw-ups are being covered by the enormous flexibility of the photographic process.

Cheers,

R.

 

[avandesande]

The easier option is just to add the bromide/bz to the tray in increments until you get the print color you want.

 

[phritz phantom]

thanks for tips and concerns so far.

say if i wanted to mix a batch of ansco 120, which has 1,8gr. of potassium bromide, how much benzotriazole would be the correct (approximatively) amount as substitute? a gram, half a gram?

 

[Photo Engineer]

Benzotriazole (BTAZ) is adsorbed to all halide grains in the paper being processed. Bromide is not. Therefore, in long term use during even moderate seasoning, due to the low concentration BTAZ is used up more rapidly than bromide and results can vary over a long run of prints - or even a moderate run.

BTAZ is therefore more reliable in a throw-away developer situation.

PE

 

[Alan Johnson]

To give some idea of equivalent amounts, Geoffrey Crawley wrote that in FX-37 the 50mg benzotriazole in the original formula can be replaced by 500mg potassium bromide,which is easier to dissolve.
Make a solution of 5g/L sodium carbonate at 100 F and dissolve 1g benzotriazole in it,each ml now contains 1mg benzotriazole.The solution will keep for years.This is Crawley's suggestion for dissolving benzotriazole, which is not easy.

 

[Dave Starr]

I use Ansco130, which calls for 22 grams of bromide. I substitute 2.2 grams of benzo, which works quite well. Using 1/10 the amount of bromide seems to be about right.

 

[Gerald Koch]

Before you start trying to do this sort of thing I'd suggest you read one of the standard works on photographic chemistry -- Haist, Glafkides, Neblette, Clerc... Otherwise you really can't have enough of an idea of what you're doing.

I'm not being rude: I have read these books, and I still wouldn't have the confidence to try this sort of thing, which (as practised by most amateurs) is very hit and miss. A lot of people think they're being clever when in reality their screw-ups are being covered by the enormous flexibility of the photographic process.

Cheers,

R.

Well said!

 

[Anscojohn]

For years I have used Ansco 103 for blackest tones with an mq paper developer. I put in one half the bromide, and ad 50 ml of benzotriazole, 10% solution to the stock. My understanding is that some bromide is necessary to buffer against print color changes as bromide is released in the developing process.
Anscojohn

 

[Zathras]

For years I have used Ansco 103 for blackest tones with an mq paper developer. I put in one half the bromide, and ad 50 ml of benzotriazole, 10% solution to the stock. My understanding is that some bromide is necessary to buffer against print color changes as bromide is released in the developing process.
Anscojohn

Hi Anscojohn,

Ansco 103 is one of my all time favorite developers. I reduce the bromide and add benzotriazole too. Is there a typo in your post? 50ml of a 10% solution would be 5 grams of benzotriazole,,,which is a lot of benzo. Did you mean to say 1% or maybe .1%? I attempted to make a 10% solution of benzotriazole once, never could get it to dissolve completely, and it resulted in massive crystalization of the solution.

I have had very good results with a .1% solution, addig 50ml~100ml per liter of working solution. This developer gives excellent blacks and print color.

Mike Sullivan