U of S | Mailing List Archive | alt-photo-process-l | Re: Mixing Ferric Ammonium Oxalate

Re: Mixing Ferric Ammonium Oxalate



Hi Camden,

I don't think that what Mike ware defines as "remaining solid" is something like a milky precipitation (if that's what you mean). I think he means insoluble impurities and/or undissolved excess AFO crystals (in case of relatively high concentration and/or low storage temperatures)...

You shouldn't experience a "milky precipitate" with AFO...

Regards,
Loris.

Quoting Camden Hardy <camden@hardyphotography.net>:

I bought some AFO to try Mike Ware's POP palladium method, and have a
question about mixing it.

From Ware's site:
Within 5 minutes nearly all the solid will have dissolved to form an
emerald-green solution. The volume will be correct (50 cc) so it does not
need to be made up. A little remaining solid may be ignored.
Filter the solution (Whatman # 1 paper, is adequate) directly into the
clean, dry, brown storage bottle, and store at room temperature in the
dark.


My question: how much is "a little remaining solid"?

I mixed a 45% solution (Ware's directions call for 60%), and it's still
somewhat milky.  I let it sit overnight, and there was still quite a bit
of solid that had settled...about 1/8-1/4 inch in about 2 inches of
chemistry...60mL bottle.

Also, he says to use a Whatman # 1 paper...is a coffee filter adequate?


Camden Hardy

camden[at]hardyphotography[dot]net
http://www.hardyphotography.net