Raw Chemicals Longevity

[Mahombi]

Does anyone know how long raw chemicals last? I've had a number of various chemicals for several years, some in their original plastic pots and others in clear plastic bags, and am wondering if they are still usable.

I don't know if exposure to light has the same effect on them as when they are mixed, but I haven't made any special effort to keep them in the dark, although they have spent their lives in the darkroom. Your views would be gratefully appreciated.

[Kevin Crisp]

It will depend entirely on which chemical it is. Hypo crystals if kept dry last forever. Others ingredients don't.

[Daniel_Buck]

I've often wondered about this as well.

Anyone know about un-opened bottles of HC-110 and TF-4? I'm assuming that they will last quite a while (years?) I'd love to know for sure. I've been hesitant to order a large quantity because I don't know how long to last. If they last, I'd love to order a larger quantity to keep handy!

[Jeremy Moore]

Anyone know about un-opened bottles of HC-110 and TF-4?

Opened up and used a bottle of HC-110 syrup this past week which had sticker date of 1998 on it. No problems.

[paulr]

HC110 seems to last many years, but i really couldn't vouch for how long it goes before you'll notice something's funny. Most liquid chemicals in that strong a concentration have a long shelf life, as do most powdered chems.

There are glaring exceptions. Powdered glycin has an annoyingly short shelf life (at least it tells you it's oxidized by changing color). Developing agents in general are more suspect than things like sodium sulfite, carbonate, etc., which should last indefinitely.

[Mahombi]

Thanks Kevin and paulr for your info. I suspected it would depend on the particular chemical.

To push this question further. Do you know of any resource website which would have this info for the various dry chemicals used in photography. Alternatively, (if you have the time and the inclination,) perhaps you could tell me what the keeping properties are for the following dry chemicals. They are;

Sod. Metabisulphite
Sod. Metaborate
Sod. Hydroxide
Sod. Thiosulphate (hypo)
Sod. Carbonate
Pot. Carbonate
Pot. Bromide
Pot. Iodide
Pot. Ferricyanide
Amm. Thiosulphate
Metol - in clear plastic container
Hydroquinone - in clear plastic container
Sod. Sulphite - clear plastic bag

They are mostly up to 14 years old. Other than the last three, they have all been kept in white plastic pots, which keep a fair amount of light out but are not opaque. The hypo has actuallly expanded in the pot and forced the lid open, thus exposing itself to air. So I suppose that will be past it's best.

[Mick Fagan]

I have every one of those chemicals in my darkroom and except for one, all were bought in April 1992 or earlier.

There was a local photographic chemical supplier who was going out of business, I purchased pretty much most of his stock for standard B&W chemistry, with a few specific for colour, like colour developing agent CD4.

I have been using this supply continuously since that date, I'm currently just starting to purchase some chemicals that are getting a bit low. Some of the chemicals that I'm using were purchased over 30 years ago, I can detect no difference between these and newer chemicals.

I am not a chemist, in fact I'm just a user of photochemistry who has learn't by purchasing a set of scales, then mixing chemistry according to published formulae.

I think you will find that the shelf life of safely stored chemicals is effectively, forever!

Mick.

[Mahombi]

Thank you Mick. That is precisely the answer I was hoping for.