GREEN IS GOOD, YELLOW IS YUCK
(temporarily ignoring the water)
Fe2(C2O4)3 is Ferric Oxalate the Sensitizer (green)
Fe(C2O4) is Ferrous Oxalate the Exposed Sensitizer (yellow)
The sensitizer reacts to light, heat, or time as follows:
3Fe2(C2O4)3 => 6Fe(C2O4) + 3(C2O4)
Following is an excerp from The Mathias Guide To Platinum Palladium
Printing, copyright April 1993, revised 1996 by Jeffrey D. Mathias:
Testing the Ferric Oxalate
Note: Testing, as with any handling of Ferric Oxalate, should be carried
out in safelight illumination.
To test the Ferric Oxalate solution:
TEST #1
Place some Ferric Oxalate solution into a shot glass.
Add a crystal of Potassium Ferricyanide (one or two crystals is plenty
to do the job).
Nothing should happen.
If it darkens, the Ferric Oxalate has turned into Ferrous Oxalate and
FAILED TEST #1 (do not consider any orange color from the Potassium
Ferricyanide).
If the solution (used in TEST #1) is OLD SOLUTION, make a fresh
solution from the stock powder and test again (TEST #2).
If TEST #2 FAILS and the stock powder is OLD POWDER (powder was
probably not stored correctly, it may have gotten hot), use new powder
and test again (TEST #3).
If TEST #3 FAILS, then the new powder is defective and should be
returned to the vender for replacement.
If TEST #3 PASSES, new solution and stock powder are OK.
If TEST #2 FAILS and the stock powder is NEW POWDER, then the
powder is defective and should be returned to the vender for
replacement.
If TEST #2 PASSES, new solution and stock power are OK.
If the solution (used in TEST #1) is NEW, then the stock powder is
bad.
If the stock powder is OLD POWDER, then it has probably been stored
incorrectly.
If the stock powder is NEW POWDER, then the powder is defective and
should be returned to the vender for replacement.
If nothing happens, continue with TEST.
Place shot glass with Solution in UV light. It should turn deep
indigo blue.
If the solution does not turn a deep indigo blue, then the Ferric
Oxalate is bad.
If this is a NEW SOLUTION from a NEW POWDER, first try adding some
more Potassium Ferricyanide. If there is still a failure to turn blue
and the Potassium Ferricyanide is good, then the powder is not Ferric
Oxalate. Return the powder to the vender for replacement. (If this
happens again, find a new vender.)
If this is a NEW SOLUTION from an OLD POWDER (that has worked
before), then somehow the solution was made incorrectly. Make a new
solution from the old power and re-test.
If this is an OLD SOLUTION from an OLD POWDER (that have both worked
before), then the Potassium Ferricyanide must be bad. nop51076@mail.telepac.pt (This is unlikely
, but there is no other reason.)
When the solution turns blue only under the UV light, then the TEST
has PASSED.
If the yellow powder is used instead of the green, the result will be a
fogged print. I also have procedures for testing for fog and clearing
problems.
Back to the dark room - Jeff
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