Friday, May 03, 2013

New Configuration

Woodbury, Connecticut

I'm having trouble with the OHP film sticking to the coated sheet of Pt/Pd paper. Pictorico doesn't do it as much as Fixxons, but the problem is still there. It may be that the material needs either a very long drying period or a short period of forced drying with heat. However the two new papers, Magnani/Revere Platinum and New Platine, both are showing that they want to be printed much drier than my old favorite Stonehenge (which no longer works for Pt/Pd) or for that matter, Old Platine which wanted very high humidity. Also, the OHP material is much thinner and more flexible than real film, which makes me think the vacuum frame is overkill for the 11x14 prints I'm planning to make. Maybe the film doesn't need to be crushed against the paper with 24 psi.

So I removed the vac frame and repositioned the exposure unit to it's normal pizza oven arrangement, using a standard spring-back frame. Since the regular window glass in this frame is much more transparent than the heavy plate glass in the vac frame, I had to do a new test for minimum time to dmax with the new configuration.

5 comments:

John Sarsgard said...

I'm using the uv source in your book, ohp premium, standard frame and Magnani/Revere. std time to dmax is 6 min. ohp premium is abt 10% more base density than std ohp and will hold more ink. I run 60% rh in the room, hang the paper after it no longer glistens and blow with a fan until dry to the touch, abt 20-30 mins. I let the digineg cure for several hours or overnight. Only time I had it stick to the pqper was using it right off the printer, and that was with stone. Keep your fingers dry! Welcome to the club!

Carl said...

John, thanks for the input. I think the vac frame is an unnecessary complication here. It is needed for 12x20 inch real-film negatives printed in a high-humidity method. If it turns out I need to use it for sufficient contact, I can always resort to a sheet of 1 mil mylar between the digital negative and the printing paper. But I think it's the pressure used by the vac frame that is causing this problem.

Carl said...

John, thanks for the input. I think the vac frame is an unnecessary complication here. It is needed for 12x20 inch real-film negatives printed in a high-humidity method. If it turns out I need to use it for sufficient contact, I can always resort to a sheet of 1 mil mylar between the digital negative and the printing paper. But I think it's the pressure used by the vac frame that is causing this problem.

John Sarsgard said...

I'm sure you're right. Don't have that issue because I never got a vacuum frame, and now probably too late to get a cheap one. Looking forward to seeing what you're printing from the diggings!

Carl said...

John, in the post at 3:30, the two DI theater shots are from digital capture. I haven't been able to make a full size print yet because a paper order hasn't arrived and I'm down to my last parent sheet. So only a few tests can be made tomorrow.