Heathkit ET-3400 red filter material?

[James Fogg]

> As I restore this ET-3400, I am curious if anyone knows what 
> kind of filter material Heathkit provided that sticks to the 
> TIL312 7-segment displays?  Mine have 4 of 6 displays 
> covered, and 2 displays bare.  It seems to be some sort of 
> adhesive red tape or film, but I have no idea what to use for 
> a modern substitute.
> 
> Thanks for any tips.

Two ideas come to mind - lighting gels, used in stage lighting, and
Kodak makes lens filter gels in a huge range of colors. Both these items
will appear to be colored sheets of plastic. In the case of the Kodak
product, the "pass band" of the filter will be narrow and precise (an
exact shade of a certain color and it won't pass much else).