Talk:Photographic fixer

Fixer License

Isn't it true that one needs a license to buy and use fixer? It has EPA regulations stating that fixer needs to be disposed in a large barrel container, and removed later by a professional service. LCecere 22:50, 10 August 2007 (UTC)

Not certain about license issues (maybe in bulk?), but here is a discussion on photo.net that contains links to other info on the topic of disposal. Girolamo Savonarola 22:56, 10 August 2007 (UTC)

Certainly not an issue in the UK where fixer can be bought freely over the counter and may be disposed of via the foul drains provided it is well diluted and only in small quantities. Professional processing laboratories need special trade effluent consents or wil need to arrange disposal by specialist waste contractor. In many countries the Silver content of spent fixer and blix makes the value of spent fixer greater than its original purchase price. Velela 23:41, 10 August 2007 (UTC)

text dump - 'washing'

I'm not sure why the following text was added here, it's peripheral to the subject. So i'm dumping it here for reference. Baffle gab1978 (talk) 03:29, 1 December 2008 (UTC)

Washing

A disadvantage of the use of thiosulfate as a fixer is its ability to dissolve elemental silver at a very slow rate. If films or papers are inadequately washed after fixing, any residual fixer can slowly bleach or stain the photographic image. For prints on high grade fibre papers, a period of continuous washing in clean, cold water for up to 40 minutes may be required. For modern plastic (resin) coated papers, washing for as little as 2 minutes in warm water can be sufficient to eliminate residual fixer. Washing aids (also called hypo clearing agents) can be used to make the process of removing fixer faster and more thorough.

A quick, water-saving, and archival technique for washing film fixed with nonhardening fixer in a spiral tank is the popular "Ilford method":

• Fill the developing tank with tap water at the same temperature as the fixer (+/-5 ºC or 9ºF)—maintaining a constant bath temperature during processing is necessary to avoid reticulation of the emulsion;
• Invert the tank five times and drain it completely;
• Fill the tank again, invert it ten times, and drain it completely;
• Fill the tank again, invert it twenty times, and drain it completely.
• The film is now washed.

More conventional darkroom practice recommends washing film for 30 minutes or longer, with a flow of water sufficient to change the water in the washing container at least three times. This is not needed when non-hardening fixers are used.

Over-washing can actually reduce the archival properties of film, as thiosulfate in very small concentrations has been shown to have a beneficial effect on film image stability.

References

Propose splitting 'Washing' section

With reference to the above text - I propose removing the 'Washing' section to its own article. I propose this because it doesn't already exist AFAIK, and because washing is a major but neglected part of photographic processes. But it's irrelevant in an article about fixers. I'll leave it for a week or so - if no-one objects I'll 'be bold' and go ahead with this proposal. Cheers. Baffle gab1978 (talk) 03:30, 14 January 2009 (UTC)

Since nobody seems bothered, I'll move it this week when I have the time and inclination. Any last chance objections? Baffle gab1978 (talk) 09:28, 2 August 2009 (UTC)

Reade "first" claim

I am removing the claim that "Hypo was apparently first used in photography by the Rev. Joseph Bancroft Reade in 1837" and its cit of a 1953 article. In a 1971 article, available here [1], R. Derek Wood debunks the 1837 date as due to Reade's faulty recollection and provides substantial evidence that his experiments actually date to 1839. In this instance, tradition coincides with truth: "Hypo" was first successfully used by John Herschel, earlier in 1839. AVarchaeologist (talk) 16:06, 7 May 2015 (UTC)

Bleach fix

If one reads the article on photographic developers one finds that iron EDTA is indeed used for bleaching, NOT ferrous (II) EDTA but ferric (III) EDTA which in oxidizing the silver is being reduced to iron (II) EDTA. It is most probable that the fresh "blix" contains iron (III) EDTA (ferric EDTA). — Preceding unsigned comment added by 150.227.15.253 (talk) 11:25, 19 February 2019 (UTC)

It is not iron EDTA but the EDTA itself that is a powerful chelating agent. The purpose of the EDTA is to keep the iron (before and after reduction to iron(II)) in solution and possibly to modify its oxidation potential. EDTA might leave the iron for some other compound that it forms stronger chelates with, but it is likely that the iron released in such a process could cause trouble (so it might be good to have some excess free EDTA). The silver might chelate with EDTA but probably forms stronger complexes with the thiosulphate.150.227.15.253 (talk) 11:53, 19 February 2019 (UTC)

In any case, as noted, it is ferric EDTA, and I changed the article. Gah4 (talk) 21:52, 27 July 2019 (UTC)

blix

The article mentions bleach fix, and its contraction, blix. Many processes separate the bleach and fix steps. Also, I believe blix is a trademark of some company. Gah4 (talk) 21:54, 27 July 2019 (UTC)