Quote Originally Posted by Ken Nadvornick View Post
Here's what I did...

Covered both slots with a single layer of filter material.
Filter material was Rosco #19 Fire polyester.
Filter material was not sandwiched between glass sheets.

Here's what I saw...

Both blue bands gone.
A single reduced green band still visible, the 1 red band still visible.
The sodium yellow intensity was moderately reduced.
That's basically what I got. Faint green, huge yellow, moderate red.

Quote Originally Posted by Ken Nadvornick View Post
Here's what I did...

Covered both slots with a double layer of #19 filter material.

Here's what I saw...

Both blue bands gone.
Both green bands gone.
One red band still visible.
The sodium yellow intensity was severely reduced.
I haven't tried doubling the filter, yet, but I think I'll give it a shot.

Quote Originally Posted by Ken Nadvornick View Post
And here's what I think...

All my original observations were made using the DVD for the movie The Hunt for Red October.* I now see that different discs have very different reflection characteristics. My original observations showed no residual blues or greens through a single layer of #19. Using the FWAAF disc I now see a definite residual green band.

My original paper fogging tests were made using only pre-threshold-exposed Kentmere Bromide #3 sheets. This should be a blue-sensitive only paper. It showed no fogging even after 30+ minutes.

Based on what I saw tonight, I now need to try Ilford MGIV VC blue/green paper to see if that residual green band makes a difference. Based on Sundowner's results, I would expect it to fog on the low contrast end to some detectable level when using my single sheet of #19 material. Then I need to try doubling up the sheets.
I hadn't really thought that different discs would show different bands, but I guess that could easily be true; I only used the one disc and I got the blue/green/yellow/red pattern you described...but I'm still confused as to why I got so much fogging when I threw the #27 filter over top of the #19, because that should have been a total cutoff of anything that could hurt the paper, regardless of sensitivity...unless something silly was happening: porous filter, paper emulsion acting screwy, etc. That's why I'm going to try the rubylith; it should be paper-safe, and if I still get fogging then something completely odd is happening.