I don't know the policies of posting from another forum but a search of the net for "color preserver test" should produce a link to the rodbuildingforun(dot)com that has an excellent post by Carlin on this subject.

That being said I have never used what is sold as rodbuilding CP. I have and do use urethane based products with good results but my favorite is a Acrylic-styrene polymer that I use to glue my inlays together.