View Full Version : Alternatives to Potassium Bromide for developer restrainer?

22-Jan-2011, 06:51
Just wondering if there are other readily available chemicals that can act as a restrainer in a developer?

Also, does anyone know how Potassium Bromide "restrains" development?


Gem Singer
22-Jan-2011, 06:56

See: S.Anchell and B.Troop, "The Film Developing Cookbook".

22-Jan-2011, 07:10
Yes, I should have mentioned that in the OP.

Benzotriazole is mentioned in my copy of The Darkroom Cookbook. But Google search doesn't seem to come up with any non-industrial source for the stuff. So, as far as I can tell, it's not readily available. :(

Any ideas on how it works or why it would be better or worse for development?

Now I find myself wondering what commercial developers might use bromide vs Benzotriazole...

back to google!

22-Jan-2011, 07:15

I found Benzotriazole! It's marketed as "Liquid Anti-Fog" and is likely available at your favorite photographic supply outlet.

Still wondering how this stuff works (what chemical action or reaction is taking place) or if there are any other outside the box versions?

Gem Singer
22-Jan-2011, 07:26
Several commercial developers use sodium or potassium bromide as a restrainer.

The developer that I am presently using, Pyrocat-HD, contains potassium bromide.

As to the actual chemical-physical way it works. can't help you there.

(Edwal's Liquid Orthazite = Benzotriazole)

22-Jan-2011, 08:06
Photographer's Formulary has benzotriazole

Michael Mutmansky
22-Jan-2011, 10:56
Bostick Sullivan and Artcraft have both I think.

John Bowen
22-Jan-2011, 13:52
I know Artcraft has it.

I would use BZ if I wanted a cooler print tone. I would use Kbr if a warmer print tone was desired. I have also used BZ and Kbr together with some fogged paper.

I haven't a clue how the chemistry works, but I know how to manipulate my developer to get the print tone I'm after.

Jim Galli
22-Jan-2011, 14:14
Leftover from my days of trying to formulate E6 developers from powder are 2 reatrainers that I later folded into my APHS lith film developer (http://tonopahpictures.0catch.com/FreestyleAPHS/DevelopingAPHSwRodinal.html).

.2% Benzotriazole, and .1% Potassium Iodide

Easy to mix. Last almost forever in a plastic bottle. Cheap.

22-Jan-2011, 14:29
Regarding how it works, search rec.photo.darkroom for old posts on bromide by Richard Knoppow. I'm sure he detailed it more than once there so if you look you will find. Or just ask the question there-RK still hangs out there.

Sal Santamaura
22-Jan-2011, 18:06
...I would use Kbr if a warmer print tone was desired...That's the conventional wisdom. I just completed a trial with my Canadian grade 2 Azo, developed in Neutol WA, in which I incrementally added Kbr and made matching prints. I enlisted my wife to evaluate the results, since my eyes said the more Kbr the colder those prints were. With no "witness leading," she observed the same thing. Guess I'll not use any Kbr, since it did the opposite of what was desired to print color and required longer exposures to boot.

John Bowen
22-Jan-2011, 20:08

I've never added Kbr or BZ to Neutol WA. Always used it straight from the bottle. Try it with MAS Amidol and Canadian Grade 2 Azo and your eyes will tell you more Kbr = warmth (and longer exposures), more BZ = cooler (and longer exposures). Azo in MAS Amidol with Zero Kbr and Zero BZ = very blue print with fog.

Vlad Soare
23-Jan-2011, 12:13
Sal, I don't know about Neutol WA, but I did try this with Lodima and Michael Smith's amidol formula, and the tones became noticeably warmer and warmer as the amount of KBr increased. The last print was downright olive.
So warming up the print by adding KBr does seem to work for me. I have no idea why it doesn't work with Neutol WA.

Just wondering if there are other readily available chemicals that can act as a restrainer in a developer?
Another restrainer, and quite potent at that, is potassium iodide. It's used for medical purposes, so I guess it should be available in drugstores.

Drew Wiley
23-Jan-2011, 14:42
It takes much less benz to do the job than KBr. On cold-tone graded papers, KBr tends to give than greenish "Dektol"cast, while benz shifts things to a cooler or bluer
tone. With graded papers, particularly warm-tone ones, the effect is more complex,
and might even depend on the color balance of the exposing light and how far the
paper development goes to completion. Some very interesting things can be done
by fine-tuning the use of these two respective restrainers.

23-Jan-2011, 21:55
You can get both Potassim Bromide and Benzotriazole off eBay. http://myworld.ebay.com/cjchemical/