Sorry for the delay in replying to your question!
When combining two potentially reactive colors that are opalescent (so we can't see through them, we can only see the surface) and also have very high contrast with each other, the visible reaction may be minimal. Also reactive colors are usually medium to dark in value, and may have a very similar value to one of the colors, so there is not enough contrast to see it well. Does that make sense?
I might be able to find some test tiles with those combinations, and show you the results we got.
Do you have photos of the reactions (or lack of reactions) that you experienced? If you can process those into images that are about 500 pixels wide, those should be easy to upload to the Forum. Then we can compare notes!
Mary Kay Nitchie
Bullseye Glass Co.
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