Yes Bill - I used to have a Unicolor filter wheel with the red, blue and green filters for additive printing, but the filters decayed long ago. I suppose it might be worth replacing them. But I find it easier to make adjustments with subtractive filters.
I'm still intrigued to find out what happens if I mount say a 3-1/2in filter on a 6in card and use the filter drawer. I'm willing to bet it will be just fine at least for 35mm and maybe medium format.
Count yourself lucky - I don't have a filter drawer, so have to use under-the-lens filter. But I have no qualms using under-the-lens filters because of what I've heard through the various experts here.
under-the-lens-filters can be used without hesitation.
But what if I were to need say three filters simultaneously? What if I were printing color and needed say 40Y+55M and I needed a 40Y and a 50M and a 5M filter? If they were all slightly scratched, would they still not impair image quality if used under the lens?
One filter is OK, but I would say with 3 scratched filters, you are going to get image degradation.
If you use under the lens filters, part of the routine is to take care of the filters, so it does NOT get scratched.
If your enlarger is assembled, you can test it.
Get 3 pieces of filter material and scratch them up. Then print with and without the filters and see what the difference is.
Good idea; as a practical matter, the filters I have are in good condition and I'd be unlikely ever to need more than two, because in addition to CMY I also have a set of red (Y+M). I was really just trying to find the edges of the issue.
Hopefully my Chromega head will arrive as advertised and the issue will be moot.