Longevity of Metol

[rcmartins]

Thanks Tim.
Meanwhile I went to the site of an international distributor of chemical and bio-chemical products and for the metol they have the following description:
color - white to faintly beige
Mine is indeed faintly beige.
raul

[Tim Povlick]

well....

The new supplies arrived and I was able to do a quick test. I tried the 'old' Metol with the new Sodium Sulfite. That was it! The new sodium sulfite did not turn the mixture to color of tea but clear.

The 'old' Metol is slightly beige whereas the new is white (not really important). The sodium sulfite looks fine and it is not that old. It was stored in brown glass bottle. I can't be certain but I must have mixed some other chemical in the sodium sulfite thinking I was combining some sodium sulfite from a second bottle to combine quantities.

So the good news is this is resolved, the Metol is good and seems to have long longevity.

Best Regards,
Tim

[Cor]

Although I do have a bit of a chemistry background, I am not a "hard-core" chemist, but I can offer a theory: If your old Sodium Sulfite was not water free (ie hydrated, you could find that information if your old stock has a proper label, something like .7H2O) it will slowly turn into Sodium Sulfate, by itself Sulfate is harmless, but it will not protect against oxidation like Sulfite as well is will not fur fill the other roles of Sulfite.

good luck,

Cor

[Gudmundur Ingolfsson]

I have Metol I bought 41 years ago and it still white and good but it is in a plastic chemical container from MERCK.

[coisasdavida]

Mine is from the 90s too, very tan, good still.