So I'm trying to get Polaroid type 55 p/n to give me a decent neg for making a cyanotype, exposing it at EI 25 and then selenium toning it for 5 minutes in KRST 1+3 to boost contrast, which it did. But, the DR just isn't there for the exposure on Weston. I've also tried different dilutions of A+B and have been able to vary the contrast a bit.
Then I stumbled upon an APUG thread that mentioned type 51 p/n which I'd never heard of before. Apparently this is a high-contrast positive coupled with a medium-contrast negative, with the print speed much faster than type 55. But, from the looks of the H&D curves off the Polaroid site, the negatives look to be about the same with type 51 perhaps having a bit more base fog. I've overlapped the two H&D curves in the attachment.
Anyone ever use this stuff for alternative processes and is there any reason to use it in preference to type 55?
Joe
Then I stumbled upon an APUG thread that mentioned type 51 p/n which I'd never heard of before. Apparently this is a high-contrast positive coupled with a medium-contrast negative, with the print speed much faster than type 55. But, from the looks of the H&D curves off the Polaroid site, the negatives look to be about the same with type 51 perhaps having a bit more base fog. I've overlapped the two H&D curves in the attachment.
Anyone ever use this stuff for alternative processes and is there any reason to use it in preference to type 55?
Joe
