RE: Ware's Cyano On Pot ... Instead of NH4 Dichromate
Hi Michael, I guess it can be used; the problem with Potassium is that it will make an unsoluble compound with the Ammonium Ferric Oxalate sensitizer. But since you're using very little dichromate for preservation of New Cyanotype, I don't think that it will harm the sensitizer and you'll already going to filter it anyway. FWIW, I use Potassium Gold Salt with Ammonium Ferric Oxalate in New Chrysotype, and I don't experience any problems with much higher Potassium concentration. Regards, Loris. -----Original Message----- From: Michael Koch-Schulte [mailto:mkochsch@shaw.ca] Sent: Sunday, April 08, 2007 8:22 AM To: alt-photo-process-l@sask.usask.ca Subject: Ware's Cyano On Pot ... Instead of NH4 Dichromate Maybe someone with experience could answer, or possibly a chemist. Would it matter when formulating Ware's Cyanotype to use Potassium Dichromate instead of Ammonium Dichromate? My understanding is that Ammonium Dichromate is used only as a preservative. Would the K in Potassium Dichromate crystalise out in a similar manner as the Potassium Iron (III) Oxalate does? Or would I be left with an excess of K ions in the mix? My question amounts to: can Potassium Dichromate be used as a substitute when Ammonium Dichromate is not immediately available. ~m
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