U of S | Mailing List Archive | alt-photo-process-l | Re: I have a question

Re: I have a question

I think formaldehyde is not the only chemical that needs
attention in disposal among what's used in cyanotype and gum

If formaldehyde is for hardening gelatin, glutaraldehyde has
easier regulatory standard and it is less harmful. Much
smaller quantity of glutaraldehyde is required, meaning you
can work with more dilute solution just as effectively,
reducing potential hazard to the user. Disposal is also
simple with glutaraldehyde.

If the amount of formaldehyde is small, and the waste doesn't
contain much of other compounds, I'd mix the waste solution
with sodium percarbonate or oxiclean and let the mixture sit
overnight at room temperature, and then dump it down the
drain. Alternative is to mix the waste solution with sodium
metabisulfite and dump it down the drain. The former treatment
irreversibly breaks down the formaldehyde by oxidation, while
the latter makes sulfite adduct of formaldehyde (which is
reversible and can form formaldehyde again later upon

Another option is to react aldehydes with a primary amino
alcohol or something at pH around 10. Again, with formaldehyde
the reaction is reversible. (But irreversible with glut.)

Dichromate should be disposed after letting it go "stale" with
the gum-mixed solution (either by light or dark reaction), or
by mixing with metabisulfite. Better yet, give it to a
licensed chemical hauler.

Ferricyanide/ferrocyanide should be given to a licensed
chemical hauler. Can't think of an easy way to deactivate
their toxicity.

Ryuji Suzuki
Q. What is your real message?
A. Keep a good head and always carry a light bulb.
(Bob Dylan, Don't Look Back, 1965)