Agreement between the verb "mean(s)" and a tricky subject "museum-quality materials"

Solution 1:

I think what you're trying to say is

(Using) museum-quality materials means your document won't discolor.

Go with means.

Using mean would imply museum-quality materials literally mean your document won't discolor, which can't be what you're saying.

This sentence is informal. If you wish to be grammatically correct, don't drop the 'using'.

Solution 2:

There is a phenomenon called "attraction", where words not in the line of grammar, so to speak, pull at our minds and confuse us. Maybe the singular "museum" is subconsciously haunting you? If "High-quality" materials do not cause you to have the same doubts about the plural "mean", this might be it.

I would use the plural myself, but "materials" is one of those tricksy words that is in practice rather intermediate between singular and plural. It is often treated as a collective noun, rather as if it were interchangeable with "stuff". So it could probably be argued the other way.