Calbe A300 fixer

jlehmus

I'm wondering about the chemical composition of A 300. Does it contain acid, and is it therefore a hardening fixer? This information isn't available in the Calbe technical papers; only hazardous components are listed there. Thank you Jukka

cfb_de

Hi Jukka, Hardening fixers may or may not contain acidic components. Acidic components have absolutely nothing to do with hardening capabilities. Standard fixers are acidic, whether they are ‘rapid’ or not. Only fixing baths for C41 processes are neutral and require the use of an acidic stop bath. A300 is a fixing agent based on sodium thiosulphate, and is therefore not a modern “rapid fixer”. It consists of sodium thiosulphate and sodium sulphite for preservation purposes. Nothing else is added. A cheap, simple, traditional formula. Hardening fixers have some formaldehyde salts added and are based on ammonium thiosulphate. Most commercial fixers (unless otherwise stated) are non-hardening fixers. Even rapid fixers are non-hardening, as both paper and film are now largely pre-hardened (except for ADOX/Efke films). Apologies for my poor English. I’m much better at chemistry than at English :-) Best regards, Franz

jlehmus

Thank you, Franz! The reason I asked is that I’ve always loved Classic/Forte films and had previously used Agfa Agefix with them, with satisfactory results, even though that fixer isn’t a hardening one. Now I’m looking for a simple, universal alternative to Agefix and was wondering if A300 would be as gentle on my ‘beloved films’ as Agefix was. Thank you for the correction regarding the role of acids in fixers – I looked at some recipes and the hardening fixers happened to list acetic acid etc., so that’s where I got the idea. No need to apologise for your English! Cheers from Finland, Jukka

tim_k

(...) A300 is a fixing agent based on sodium thiosulphate, and is therefore not a modern ‘rapid fixer’. It consists of sodium thiosulphate and sodium sulphite for preservation purposes. Nothing else is added. A cheap, simple, traditional formula. (...)

I don’t know if they ever changed the formula of their A300 fixer, but as far as I know, it is a fixer based on ammonium thiosulphate (as you can read in the product information; I suppose the letter A in the product name also indicates that):

(...) This lightweight powder fixer, based on ammonium thiosulphate, (...)

Though I admit the A300 is a very slow fixer, much like fixers based on sodium thiosulphate, if you use the amounts of water specified in the manual. Apologies for posting on this old thread, but this is still a relevant result on Google and I just wanted to mention/correct this.

MirkoBoeddecker

The recipe was changed in 2010! The recipe was changed (much to our dissatisfaction, without anyone being notified). Best regards, Mirko

Steffen

[sup]What does it consist of now? Sodium thiosulphate or ammonium thiosulphate? I'm confused.[/sup]

ThomasPauly

Why is this important at all? Among developers, it is clear that different developing agents produce significantly different results. But what about fixers? Of course, there are differences in terms of processing times, yield, shelf life and wash-out speed; as far as the quality of the results is concerned, however, I haven’t noticed any differences. Have I overlooked something here?