Preserving Pyrite fossils in Shale Matrix

Personally I don’t think there is anything more beautiful than a premium fossil specimen still in its matrix (don’t tell my girl friend that). Anyways, I’m hoping that someone on here can share their wisdom with me as to what I can do to preserve pyrite fossils in shale matrix, so that the end result doesn’t take away from the fossil.

I’m looking for a lacquer, glue, varnish, etc. that I can find at a local shop that I can apply to the shale that will keep it from deteriorating and will keep its matte look. I’m also looking for something I can apply to the pyrite fossils once it is cleaned that will prevent future oxidation and allow it to stand out from its matrix.

I’ve also been contemplating trying to find something I could coat the shale in (like Vaseline), so that when I expose it to Iron-out, only the pyrite is exposed. If I could figure this out, then I might not have to treat the shale with any preservative as it should still be fairly strong.

I would have tried this myself already but frankly I don’t have a lot of extra money to spend on random liquids and I’m fearful that applying glue to the shale or pyrite could cause an unforeseen chemical reaction (I got a C in chemistry 12 years ago). The last thing I want to do is ruin something that sat in the ground waiting for me to find it for the last 140 million years.

Thank you for your time and willingness to share your knowledge

What the professionals use is polyvinyl acetate, this is sold by the Black Hills museum (www.bhigr.com/store/home.php?cat=37). Its not expensive and I have been using it. I dry the specimen in acetone first (moisture is a killer!). Then soak it in polyvinyl acetate dissolved in acetone. Al