Re: Help with what I believe is a hardening issue

Hi Jack!

That's all very well, as long as you can accept the uncertainties. The
"white substance" is a polymer of the formaldehyde, and means you no
longer have a 37% solution. Also, formalin this old will have very
significant amounts of formic acid, also formed from formaldehyde,
through oxidation and disprop., further reducing the actual formaldehyde
concentration. This may or may not interfere with what you are doing,
you will have to be the judge of that. If you choose to use formalin
this old, you need to pay very close attention when you finally purchase
new stock. It will be quite different from the last drops of your old
bottle...

Best regards,

Tom Einar Andersen

Jack Fulton wrote:
> I've had, since the late 1960's, a gallon of Formalin (37% formaldehyde)
> which is the primary form used in photography. It comes from a local Bay
> Area laboratory. There are a few small flakes of a white substance on
> the bottom of the heavy duty plastic jug and other than that there seems
> to be zero deterioration.
> Jack Fulton
Received on Mon Nov 22 09:45:05 2004