Testing Potassium Bromide and Carbonate Solutions

[Vlad Soare]

Hi guys,

Is there a quick-and-dirty way of telling if a solution of potassium bromide is still good?
How about sodium or potassium carbonate?
All of these are said to keep indefinitely, but it would be nice if I could somehow test them from time to time, to make sure they're still OK before risking a film.

Thank you.

 

[Removed Account2]

They keep *forever*, if you mix about a years use, you're good.

 

[ruilourosa]

the real problem is water, if the products are in a hygroscopic form you could be using more water than reagent! other problem could be contamination, but if so, you are way too messy to make solutions. A simplist way to determine purity should be target ph, other way could involve some CSI machines, a really expensive process, just buy another kilo of the stuff from a reputed dealer and cap well, i use new jam jars with rubber sealants, reagent bottles and sometimes saran wrap to keep things clean. I have metol and hidroquinone with 40 years and they are good as new.

 

[Gerald C Koch]

You don't mention concentrations which would effect the answers. I assune you mean fairly concentrated solutions 5% or greater.

The following information may be helpful. Care should be taken in the selection of the bottle material for photographic solutions. Look at the SPI (recycle number within a triangle on the bottle) to determine the type of plastic. SPI 1 and 3 are good to prevent oxidation of developer solutions and SPI 2 and 4 are good for stopbath and fixer. Glass is good for all but highly alkaline solutions which will eventually etch the glass and leave a precipitate of silica in the bottle.

If keep in well sealed bottles at room temperaature the solutions should keep for at least two years.

 

[Vlad Soare]

You don't mention concentrations which would effect the answers. I assune you mean fairly concentrated solutions 5% or greater.

You're right. My mistake.
The potassium bromide solution would be 10%. I'll use it in formulae that call for amounts of bromide too small to be measured accurately, like ABC Pyro or Michael Smith's amidol print developer.
Sodium carbonate would be either 8% (the C component of ABC Pyro) or 20% (the B component of Pyrocat).
Potassium carbonate would be 75% (also the B component of Pyrocat)

I'm using glass bottles almost exclusively, except for extremely basic solutions (like the activator of the thiourea toner, which is 10% sodium hydroxide).

Thanks.

 

[Photo Engineer]

Bromide solution will not decompose and will keep forever. You should stir gently before using.

Carbonate solution can decompose slowly, and thus change in pH slightly. You should keep it tightly capped and an inert atmosphere would not hurt. Stir gently before using. Use a high quality glass bottle for this or a thick plastic. Concentrated Carbonate can etch some cheap glass but not as badly as Hydroxide solutions. Etching of glass, if it takes place will contaminate the solution. This is unlikely, but has been known to happen.

PE