chemical composition of photographical solutions

1- what is the base chemical composition of photographical solutions

(fixer bleach...)?

2- what occur to this solutions when we store them for long time?

thanks

Try searching Kodak's MSDS database for the many answers to the first part of your question. There's no simple answer, since most photographic processing solutions contain several compounds. There are also many different and sometimes secret combinations of chemicals used in proprietary developers, fixers and bleach baths.<br>The manufacturer's Material Safety Data Sheets are the nearest thing you'll get to a published formula in many cases.<p>The maker's documentation will also provide you with the keeping properties of the chemicals too.

1) B&W developers - some combination (there are thousands) of a developing agent(s) plus buffers and an alkalizing agent (sodium metaborate or borate, or a hydroxide). Stop baths - citric or acetic acid solution. Fixers - Anhydrous sodium thiosulfate plus sodium sulfite plus other additives depending on purpose (Sulfuric acid for hardening, etc.) Hypo-clear - sodium sulfite, sometimes with aluminum sulfite added.

 

Here's a link to some representative formulas - there are housands of others:

http://unblinkingeye.com/Articles/Developers/Formulas/formulas.html

 

Color developers contain much more complex organic solvents and compounds to create the organic dyes that form color images - you get into names like 2,3,4-trimethyloxy-3,5diamino---(25 more letters)----phenol. These you'll have to look up for yourself (see first answer).

 

Color bleaches often contain a fair amount of ferricyanide since it's a good silver solvent - it adds the deep red/yellow color to the mixture. Bleach for silver-reversal processes (like Agfa Scala) usually contains mostly potassium permanganate.

 

Color fixes are fairly close to regular B&W. At one time color-process stabilizer baths contained formalin to 'fix' and preserve the color dyes the same way it 'fixes' and preserves bio-lab specimens - I don't know if that's still true.

 

2) They go bad.

 

But it's variable. Generally speaking, organic (carbon-containing) compounds are most likely to 'spoil' just as they do in food - it's the paraminophenols and hydroquinones that go bad first. The sulfates and sulfites and inorganic acids/alkalis tend to last a long time

 

Sodium sulfite has a preservative effect on photo chemicals, just as it does in wine and on salad bars. It also buffers some reactions, which is why it's a good preservative. So it tends to turn up in almost every photo formula, from developers to fixers to fixer clearing agents.

 

Oxygen and UV/blue light are most likely to cause spoilage - thus full, sealed, brown-glass/plastic containers are the best defense.

 

And dry powders last longer than solutions - usually (cf. Xtol).

In high school we used old war surplus FIXER in green or blue drums. It was all stuck together due to humidity; and a decade or more past expiration. One had to use a big ice pick to break off big chunks of fixer. Then we used a mortar and pestles to grind it up . We weighed it out on a gram balance; and figured the water in ml to make a batch..The negatives fixed with the ancient fixer still look fine today.

"...Hypo-clear - sodium sulfite, sometimes with aluminum sulfite added..."

 

Should read "...AMMONIUM sulfite added...

 

d-ooo-h!