I could be wrong, but I have been told that the ugly fluff that grows out of solder seams is actually pickle residue that is trapped inside microscopic pores in your solder seam. If you use a pickling acid, You should always neutralize with baking soda in water once all fabrication is complete. err on the side of caution, let it soak for a day if you can.

I have used Renaissance Wax as a clear coat. Its Archival, and it smells good.

Personally, I am all for leaving mounts brass. In a lot of cases, I think it looks much better than trying to cheat the eye with acrylic paints. I have even patinated brass mounts before to help minimize their visual presence. Again i emphasize the importance of neutralizing with baking soda and water. If only I could convince more curators to let me do it....

Michael Studebaker