Alkaline fixer?

andynguyen · Post by **andynguyen** » Wed Mar 09, 2016 8:15 am

Dear all,

First off, i know F6 alkaline fixer formula. but it uses sodium thiosulfate. & according to recent (up until photochemical labs shut down) it's been suggested that sodium thio doesnt fully clear the film (quoted from books).

So i've been using Agfa fixer for x-ray film (which i obtain from medical suppliers in town). It's rapid. So it probably contains ammonium thiosulfate instead. which is great. But it's acidic. I tested it with yellow litmus paper, the pH is around like 4-5.

But i'm trying pyro & i dont wanna lose the stains by using acidic fixer.

I compared the formula & it seems to me that the difference is just the pH modifers put in to alter the pH. Main ingredient is the thiosulfate. Acidic fixer has got bisulfite & acetic acid. Alkaline one has carbonate & borax. The Agfa fixer smells acetic, too.

Then, my question is: can I just add sodium carbonate, or sodium hydroxide until the Agfa fixer show up alkaline? then use it as if it's an alkaline fixer. I have both chemicals.

Any insight would be greatly appreciated.

Post by **sanchell** » Wed Mar 09, 2016 2:24 pm

Greetings, Andy. Bill Troop is one of the leading authorities on alkaline fixers after Grant Haist. I have asked Bill to respond to your post.

Bill Troop · Post by **Bill Troop** » Wed Mar 09, 2016 2:59 pm

That's an interesting question. The problem with altering a commercial formula is that you can't know exactly what's in it. Suppose it has a hardener: if it's an aldehyde, it could polymerize if you alkalinize the product. If it's an alum hardener, it will sludge out. But if there is no hardener and the product really contains only ammonium thiosulfate, sulfite, and acetic acid, then there should not be a problem GRADUALLY adding a carbonate solution to bring the pH to about 7.5. I would not go higher. If the solution remains clear, you may be OK.

But I would not do this because I have no way of knowing what is in the product.

Is it impossible for you to make up your own fixer from the basic chemicals? Regarding sodium thiosulfate, the day may come when we have to live with it, if ammonium thiosulfate becomes too expensive. One interesting solution would be to have a mixed sodium/ammonium fixer, using ammonia salts to partially convert the sodium, as in Kodak F-7. I am working on some of these ideas to present in FDC 2.

However, I understand that economy can sometimes be an overriding issue. In that case, this is worth a try. If the solutions looks OK, you should be OK. And you certainly should have a good deal of pH stability, once you have edged past neutral territory, due to the high amount of buffering you will have created. Whatever the case, be sure to test often for film and paper clearing times, and be sure to fix paper for at least twice the clearing time and film for at least three times the clearing time. Keep in mind that washing times will be much more rapid once you have moved into alkaline territory.

JB Harlin · Post by **JB Harlin** » Wed Mar 09, 2016 5:51 pm

I would whole heartedly agree that I, personally, would never modify any solution that I did not know the contents there of. Just me, but you open up a bag of worms by guessing. I am not chemist and I stick with what works and leave all that experimenting to those that know more than I.

I can tell you that I have had ten plus years experience using staining developers. We use Kodak Rapid Fixer, film strength and Do Not add the Hardener. Not sure of the PH of their rapid fix, but I have been told it is a low acid fixer. Gordon Hutchings recommends Kodak Rapid Fixer and we have used it for all staining developers we have used. Gordon also recommended to me to use a very weak acid stop bath. I mix 2ml of 28% acid to 1,000ml of water. Never had a problem with any staining developer.

One thing to keep in mind is the stain should be proportional to the density of the negative. Base stain, that is to say, staining of the clear film base is of no use. It is no different than overall fog. A properly stained negative will have nearly clear film base. You many not even see the stain unless you compare it side to side with a negative that was processed in a non-staining developer. Hope this helps. Rather than go on and on, here is more info. . .

http://jbhphoto.com/blog/formulas-updated-07142015/

http://jbhphoto.com/blog/2011/07/28/sto ... evelopers/

http://jbhphoto.com/blog/2013/08/20/pyr ... nal-stain/

andynguyen · Post by **andynguyen** » Wed Mar 09, 2016 7:42 pm

Thanks Steve, Bill & JB!

It's true that i run a risk of bumping into some unknown ingredients. esp since the thing is designed for x-ray film & nobody know how the film base differs from photo film.

I wasnt aware that Gordon recommended Kodak Rapid. That thing has a pH of 4.9 & should be the most acidic there is. But well, since he recommended so, then that should mean that pH has little to no effect on the image stain. & i shouldnt be too concerned about it.

Thanks a bunch, guys!!! I'll check your links, JB!!

JB Harlin · Post by **JB Harlin** » Wed Mar 09, 2016 7:55 pm

I went to Gordon's book "The Book of Pyro" to be sure I read it or got it directly from him. If you look at page 18 he says, rapid fixers containing ammonium thiosulfate, if used without harder, are fine. He uses Kodak Fixer F24 and gives his 'Spoon Formula' on the same page. I have always used Kodak Rapid Fix, without the hardener. Gordon says, 'the hardening agents reduce the image stain.' I would imagine because the hardener is acid.

Hope this helps!

andynguyen · Post by **andynguyen** » Wed Mar 09, 2016 8:05 pm

I personally tested my Ilford Rapid fixer, it's acidic. The Agfa is acidic as well.

The kodak rapid fixer is also acidic, according to its MSDS data.

The Ilford & Kodak fixer, by now, should no longer contains hardener since it's not neccessary with new emulsion, as I've read.

On the other hand, the Kodak C-41 fixer is neutral.

Oh well, i'll try again with PyrocatHD.

JB Harlin · Post by **JB Harlin** » Wed Mar 09, 2016 8:21 pm

Gordon also recommends the Formulary TF4 fix. I would bleive, from my experience, any rapid fix without hardener will be fine. As usual, I would test to be sure, but I would expect you will have good results. Be sure to let us know how things go!

Bill Troop · Post by **Bill Troop** » Thu Mar 10, 2016 7:27 am

My memory is that Gordon showed that the more alkaline (or less acid) the fixer, the greater the stain. I would say, if you're getting the degree of stain you want with an acid fixer, fine, but if you want more stain, which I think is a good thing, then you would probably move to a neutral-to-alkaline fixer. As long as stain is proportional to the image, it is free density, with maximum enhancement of image quality. Whatever you use, you are likely to get a beneficial stain effect, it is just a matter of degree.

Post by **sanchell** » Thu Mar 10, 2016 8:05 am

There are many ways to get there. I have been using pyro, ABC, PMK, WDHD+, D7, and more since about 1974. For me, the only fixer to use is Formulary TF-4 or TF-5. There are many things I like to play with, developers, toners, but I don't mess with fixer. End of story.

BTW, Bill mentions FDC2. Probably everyone on this forum know what he's referring to. For those that may not, Bill is working on a complete rewrite of the most important book on darkroom procedure ever written, and I include the DCB in that assessment, The Film Developing Cookbook 2nd ed. It should be out later this year and I am extremely excited about it.

While Bill has done me the courtesy and honor to leave my name on the cover, the 2nd edition is entirely his effort.

Bill Troop · Post by **Bill Troop** » Thu Mar 10, 2016 4:33 pm

I want to make clear that FDC couldn't exist in any form without Steve. I will be seeking his advice on a number of issues for the 2nd edition.