Confused about fixers

[Todd Barlow]

Here is what I have read:

Photographers Formulary's TF-4 and Kodak's Rapid Fix are both based on Ammonium Thiosulphate and both are considered rapid fixers.

TF-4 is non hardening therefore does not have to have an acid environment that the hardener needs to work. Kodak Rapid Fix can be a hardening fixer with the addition of the Part B Hardener solution, so I assume that the Part A solution is acidic.

i) What component of a fixer formula causes it to be considered an acid fixer?
ii) Can fixers based on Ammonium Thiosulphate or Sodium Thiosulphate be formulated to be either acidic or base?

Thanks

Todd

Enjoying our 25 cm of fresh new snow (hopefully not acid snow)!

 

[Nick Zentena]

i) the acid.

ii) yup.


That's more snow then us-)

 

[Ole]

Nick's answer is brief, to the point, and ... brief.

The rationale behind acid fixers is as follows:

1: acid fix removes the "unsightly stain" from certain developers like pyro (and that's a quote!).

2: The most useful hardeners need an acid environment to work.

3: If the stop bath has lost its acidity, the fix stops development dead.

So the reason for alkaline fixers will be - so what ?

 

[fhovie]

High PH - Shorter wash times - Better archival prints - Better with staining developers - faster fix times - great capacity. - I only use Ammonium Thiosulfate fixers (TF3) - especially with my handheld 8x10 ... Ole ;o

 

[BarrieB]

Greetings All; I always use the 'Two Bath' fixing for prints, Shorter fixing times AND longer life for the fixers. Barrie.

 

[Nick Zentena]

I've never been called brief before. Must be the snow.

I'm not sure I understand the comment about high pH fixers being faster. An acidic sodium thiosulfate fixer isn't going to fix much different then one with a higher pH. Rapid fixers are faster then sodium thiosulfate ones but that's not a pH issue.

 

[rjr]

Nick,

the alkaline fixer makes the emulsion swell, allowing the thiosulfate to penetrate it faster and thus accelerating the fixing... and the washing.

At least in theory... ;-)

 

[photomc]

Not trying to HJ the thread..but have been using Ilford Rapid Fix and now it has gotten hard to find would like to find a replacement before I run out.

What I would like is something that will last as long as the Ilford RF, but something I could mix - don't want to pay shipping for the H20.

Recommendations?

 

[Tom Hoskinson]

Not trying to HJ the thread..but have been using Ilford Rapid Fix and now it has gotten hard to find would like to find a replacement before I run out.

What I would like is something that will last as long as the Ilford RF, but something I could mix - don't want to pay shipping for the H20.

Recommendations?

Try Ole's Fix (OF-1). It is listed in the APUG Chemistry Recipes.

(there was a url link here which no longer exists)

 

[Peter Schrager]

Fixer

Photomc-check out Fineartsphotosupply. I'm using the fixer made for Tgrain films which has a long life and works beautifully for pyro negs. This fixer is only for film but is VERY economical and you mix it yourself. For prints I only use NAthiosufate which I buy 100LBS. at a time locally. I may get heat on this but straight fixer works fine for my prints.

 

[Tom Hoskinson]

Suitability of straight Sodium Thiosulfate for fixing paper depends on the paper's emulsion chemistry. It works fine with Azo, for example.