psvensson said:I mixed it yesterday for the first time, and I'm a bit worried that I goofed. The solution is still strongly green, and I think it's supposed to be yellow. Could the room lights have been too strong? I did it under ordinary bathroom lighting, only realizing afterward that it might be too bright.
The one way to find out, of course, is to coat some paper and try it, but I won't have the opportunity to do that for a while.
psvensson said:I thought the purpose of acidifying the clearing bath was to prevent excessive clearing of the blue salt? If you want more aggressive clearing, wouldn't you just let the water be?
psvensson said:Bostick & Sullivan shipped the ferric ammonium oxalate in a white plastic bottle that obviously lets through light. That doesn't seem like a good idea. According to Ware, the solid salt is sensitive down to green light. I've written to B&S about that, but haven't heard back yet.
psvensson said:I've run more tests, and it's pretty clear that my water causes massive loss of density unless acidified. It might have to do with differences in our water supplies.
I just realized that adding just a little bit, like half a teaspoon, of potassium ferricyanide to the first clearing bath (along with 1 tbsp citric acid for 1.5l water) deepens the D-max tremendously. It's the kind of blue that you have to look twice at to make sure it isn't black. It also makes the paper almost more contrasty than enlarging paper.
castilg said:Not bad what paper did you used? and exposure time?
Donald Qualls said:This is what I'd expect with an alkaline water supply. Acidifying the wash water as you've done is the simple way around it. Unfortunately, cyano requires too much water to use distilled for the development/wash, at least if you have to buy your distilled water -- if you have a distiller, it might be practical to wash in distilled.
Now *that* is a neat trick. I suspect, however, that it's equivalent to peroxide treatment -- that is, it's just oxidizing the Prussian blue to its maximum density. Have you tried the bath in very dilute hydrogen peroxide as a comparison with your ferricyanide additive?
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