That's part of the idea...Originally Posted by Dracotype
According to Terry King and others, the ferric oxalate gives less speed, but better quality than ferric ammonium citrate. However, I need to PM Gustavo Castilla and ask how he goes about developing; I note in his article (such as it is) that he uses a weaker potassium ferricyanide solution (30 g/L instead of the 50 g/L I have for traditional cyanotype). The problem I've had with development isn't as much unevenness as brushing away the forming image while trying to get enough solution on to produce even development. Gustavo is getting very even and dense results; I'll find out how.The increase in speed might be more significant if the oxalate salt of iron was used, but I have no data on this. Only a suggestion.
I thought of developing in a tray with the solution, but that's a lot of ferri all in one place, and I don't have a huge amount to play with (though it's not very expensive, and I'll probably get more when I order chemicals Real Soon Now). Worse, I can't find the 5x7 trays I thought I had (I'd bet they're off looking for my 9x12 cm to 3x4 inch plate adapters, which I haven't seen since I moved, despite now having film sheaths for them).I think that the traditional method for cyanotypes shows an advantage when it comes to development. The two solutions are on the paper. With brushing on the ferricyanide, you open the possibility of uneven development. Perhaps if you had a super saturated solution of potassium ferricyanide that you developed your print in? That might take care of washing away the ferric ammonium citrate to early. Just a suggestion.