RE: Mike Ware's POP Pt./Pd. Pt
One issue I have seen with a few of the AFO PT./Pd. is small white spots, irregular in shape and some larger than others, and all in the shadows and lower mid-tones. I suspect that they may be caused by the sensitizer separating from the paper during exposure, or more likely when the negative is separated from the paper after exposure, perhaps due to moisture content. I use a vacuum frame and the pressure, even though not great, may cause the separation. With FO Pt./PD I typically dry the coated paper only about fifteen minutes and have never had this kind of issue. With the POP process I am finding that there is some risk of the white spots unless drying times are much longer. As I mentioned earlier, I am working in a room with RH of about 50-55%.
Of course, the problem might be something else, such as something in the sensitizer or method of coating. I am very new to this method of printing and still trying to learn to recognizes the cause of problems.
At 7:56 AM +0200 11/10/06, Loris Medici wrote:
I agree (that probably something's happening to the paper fibers not to the noble metal itself)... I only use Citric Acid and Sodium Sulfite + Na4 EDTA to clear my prints - usually just Citric Acid. I include Sulfite + Na4 EDTA into the process only when I'm using FO sensitizer and / or when the sensitizer contains KAuCl4 - because a stain will remain otherwise. Regards, Loris. -----Original Message----- From: EJN Photo [mailto:firstname.lastname@example.org] Sent: 09 Kasěm 2006 Persłembe 23:31 To: email@example.com Subject: RE: Mike Ware's POP Pt./Pd. Pt Loris, It could be that if only di sodium is being used that the buffers in the paper are being used up and the paper is losing some strength. I follow Di Sodium baths with tetra sodium; with both my FO, AFO, PT/PD as well as with Chrysotypes.