OK, I appear to be wrong! I received the red LED bulbs earlier this week. I re-tested my current setup with multiple 0C filters that had tested "safe" before, and it tested safe again. I then used the same procedure using the pair of new LED bulbs, and they, too tested safe.
Originally Posted by David Brown
(I probably should have tested just one LED bulb first, but I reasoned that if the pair passed, I wouldn't need to test just one by itself. Turned out to be true.)
I then combined the new LEDs with my current safelights and tested that, and also got a "safe" test. I was both surprised and pleased. I finally extended the test from 7 minutes (using the Kodak procedure) to 10 minutes and still got a clean, safe test!
I use the Kodak method http://www.kodak.com/global/en/consu...Safelite.shtml. This is very similar to the Ilford procedure http://www.ilfordphoto.com/aboutus/page.asp?n=148.
The Kodak test goes to 7 minutes. It was a simple step to add another 3 minute exposure to get a cumulative 10 minutes of safelight exposure. All of this was done with Ilford Multigrade paper.
Disclaimers: Different papers must be tested for, and each darkroom setup, or change thereto, must be tested.
Therefore, all this proves is that the specific LEDs mentioned by the OP work in my darkroom with Multigrade. It does not speak to all red LEDs, other types of red bulbs, strings of Christmas tree lights, etc.
My task in the near future is to re-arrange my safelight set-up for efficiency, incorporating the new LEDs (and probably eliminating some of the older units). This new set-up, of course, will require re-testing. I may write all of this up in detail and put it on my old darkroom blog, or maybe here on APUG as an article, or both. The procedure for testing is tedious, but thorough. The most difficult part (aside from distilling the slightly verbose instructions down to the actual steps) is determining what "enlarger exposure is required to produce a light gray tone on the photographic paper with standard processing". In other words, you have to determine the minimum threshold exposure of the paper and make a white-light exposure to push the paper to this level. Then there are two sets of safelight exposures made, one with the threshold exposure made before and one after the safelight exposure. I am guessing this is the most misunderstood (and probably neglected) part of testing safelights.
Anyway, bottom line: my darkroom is now about 3 times brighter when printing! And safe ...