Quote Originally Posted by Ronald Moravec View Post
Go with the filter sold by manufacturer. Rosco gels come in large sheets and the code number is printed only in one corner. Depending on where the cuts are made, it may or may not show up.

I use the gels in green and blue as VC filters for Aristo cold light head using all the grades of each, 1/8 to full. The man who made Aristo heads put me on to it.
I'm about at the point of trying a fresh filter from Freestyle (or whomsoever retails them) just to see what happens. The sheet of rubylith came in today, though, so I'm going to test that out tonight...and if I still get fogging then I'll know something silly is going on, somewhere, although I don't know what it could be. I've developed an unexposed strip and gotten pristine white, so I know the emulsion isn't just graying over time.

Also, I never thought of using blue/green gels as cold light filters...that's pretty innovative!

Quote Originally Posted by Greg Davis View Post
I did another safelight test this morning. First, I used a CD as Ken spells out to check for other colors of light. With the vanes wide open, and the Yellow tape filter in place in the bottom, the Red tape filter in the vanes, I saw no color except yellow. Still with the vanes wide open, I exposed two pieces of paper to the safelight, one was flashed before the safelight exposure, the other afterwards. Both showed signs of fog after 3 minutes in the flashed area, none in the borders. Both showed fogging at 7 minutes in the flashed area, none in the borders. My previous test was done in a different darkroom and I cannot guarantee there wasn't a light leak.

I expect better performance with the vanes fully or partially closed.
I didn't even make it to three minutes; based on what I saw on my very-inelegant coin test, I had near-immediate, sub-1-minute fogging...but I halfway expected that with the green band that I saw. I wish I could get a picture of it; the best I can say is that it looked like a fuzzier version of the sodium spectrum that was linked-to earlier in this thread, excerpting the blue band. I know I don't have light leaks, because nothing has changed in my darkroom except this safelight and heretofore I could leave Oriental out for an hour without a trace of fogging...and that was a long, boring hour, let me tell you.

Quote Originally Posted by Ken Nadvornick View Post
Hmm...

If the set of filters you are using, regardless of where they came from or what material they are made of, are successfully removing all of the extraneous higher wavelengths above the sodium D-lines doublet at ~589nm, then the only other immediate explanation is that the paper emulsion sensitivity is bleeding over to some degree into that wavelength. Either because it was designed to do that, or it has aged to do that.

Or something else silly is going on. Like, say, a leaky paper safe. When I did my testing I did take new sheets of fresh paper directly from the box it came in while in total darkness, then held them in a clamshell safe that I also occasionally use to store loaded film hangers, while the Duplex warmed up. I don't really think this is it, but it is a very slight possibility.

I am now looking for some time here to go down to my darkroom and also repeat the CD wavelength check. Maybe tonight.

Perhaps my color vision is slightly different than his and I missed the very faint residual green line that 'Sundowner' observed. Since I tested on Kentmere Bromide, which should be blue-sensitive only, I would still have seen no fogging if, as he observed, all of the blue was removed.

Tests on VC paper (which I haven't done under the Duplex) would be a different story however, if there was some minor residual green remaining. And I do note that if one looks at the Rosco transmission chart for the #19 filter, there IS a very slight transmission of greens. It looks to maybe only be 2-3%. But it's definitely there, if the chart is accurate.

For the record, of late I've been using only the red LEDs because I got into working with some Slavich graded bromide, and that paper is marked as red-only safe. Then when using MGIV I've just continued with those LEDs.

Ken
Maybe it's the VC paper I'm using, then; I don't know how green-sensitive Oriental's Seagull VCFB really is, but now that I think about it my splint-print soft/hard exposures - I use Ilford's MG 00 and then the 5 - are actually pretty close to each other, time-wise. Heretofore, the hard exposures were always longer because of the one-stop light loss, and when I printed on Ilford MG-IV the exposures were usually in a 1:2 ratio. Perhaps, then, Seagull is more green sensitive and I have a compound problem. Thoughts?

Quote Originally Posted by Greg Davis View Post
My paper is a brand new box of MGWT, the paper is taken from the box, not a safe. PM me your address and I will send you some of the filter material I am using, which is the same stuff in the filters sold by Freestyle and others for these safelights. You can try it out yourself.

And as I said, I get some fogging when the vanes are wide open after three minutes, but closed down, I get much longer times while still bright enough to work easily.

I should note that I am using these Kodak instructions to perform the test.
I was going to move on to that exact Kodak test after successfully completing my ad-hoc coin test; haven't made it that far, yet.

Quote Originally Posted by Roger Cole View Post
Defective #19 filter?
I've wondered that, actually, simply because I found a LOT of information on rebuilding the Thomas with the #19 filter and when I did so I got results that seemed very atypical. Either that, or I'm really much more incompetent in the darkroom than I suspect...and that's an accomplishment!

I'm going to go in and try a test with the rubylith right now, and see where I get. I'll post some results in a bit...