Well, 400nm violet is in practice as energetic as 401nm UV. Limit is a bit artificial.
Well, 400nm violet is in practice as energetic as 401nm UV. Limit is a bit artificial.
Interneg - I just noticed your question. Yes, it concerned a hypothetical method for making interpostives from color negs, t it then to b&w internegs, for sake of exposing onto regular matrix film rather than Pan matrix. He never actually tried it. I did. It's quite tricky. I should hit the nail on the head a second try, but have no interest in that wild experiment for awhile. I did get a wonderful print from the original color neg onto Fuji Supergloss medium. And I took the green separation neg to make a very nice b&w print onto MGWT due to the wonderful expansion and greater contrast of the separation neg. So it was worth it and fun to try at least once. Pan matrix film could be made again if someone was really determined. I bought out most of the last of Efke matrix film, which was based on Jim B.'s formula, but most of it remains frozen.
I should add that if I had done the double neg method using TMX100 for both the interpos and interneg, it would have been easy. But since I was just having fun and trying to save money, I only used pricey 8x10 TMX for the first step, the actual color separations.
The biggest headache seems to be what the black absorber dye actually was - or if it was a dispersion of carbon black in the gelatin. Some of the patents that seem to relate to the revival of Technicolor in the 90's suggest the latter, but it's never been entirely clear what was used in Pan Matrix.
And all because I want to make colour darkroom prints with a 5K type of finish...
Jim Browning could tell you; or at least he has made it known that his own formula of matrix film could easily be tweaked to pan sensitivity. You even have to be extra careful with the intensity of red safelight conditions using it. The newest matrix film being used in Germany is designed for blue laser exposure, so might be quite different; but it's not available for public sale anyway. At my age, I have no interest in building my own slot coater. I'm having a hard enough time just getting back to regular dye transfer experiments, though what I was really learning to do was a modernized tweak of the previous wash-off relief technique, which is more practical for me. In the meantime, I'm really buried under a big backlog of RA4 printing, which I've got good enough at to truly rival or excel DT in certain respects, lots of new black and white printing work, and a huge backlog of drymounting.
Drew - I think you might be referring to a bit in Ron Mowrey's emulsion making book where he suggests a possible route & dyes to making pan-matrix subsequent to an appendix containing the Jim Browning recipe - and explains the need for a black dye (but doesn't specify anything that might be a suitable candidate) in place of the yellow dye used in the blue sensitive matrix film, as well as most of the other headaches involved in making pan-matrix work well.
What are you using for your bleach in the wash-off process? I'd like to avoid the dichromate bleaches like R-10a if possible.
My wash-off relief method does require a bit of ammonium dichromate - nasty stuff, but I do this in drums, so not much risk. I haven't researched an alternative yet. Please note that I'm a beginner at this. I do know how to make very precise color separations and masks, but just haven't had time to get too far into actual printing other than the basics, to confirm that my method does work well. I've developed matrix film both the official quickie dye transfer way and, to my thinking, the preferable slower wash-off relief method, which gives me better process control because it's not so rushed, and is way more economical. I use HC-110, but it's been commercially done with DK-50. The Efke matrix film tends to have minor blemishes or specks from bits of gelatin floating around that got re-deposited on the film during mfg; but it's not a huge problem because DT is not an extremely sharp process under the best of circumstances and doesn't warrant especially close scrutiny. The strong point is the potential for hue control and the transparency of the dyes. I just want to do it for fun and the challenge; there are far easier ways to make excellent color prints in the darkroom. But I haven't looked at Ron's book. I e-chat with him frequently. It's amazing that he's still so active at his age.
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