how to apply cerium oxide to polish polyurethane plastic

Cerium oxide is used quite a bit by amateur telescope makers, to put a final polish on mirrors. It's a quicker-acting substitute for jeweler's rouge (and boy, am I ever showing my age by remembering when that was the standard!) With either, you use water. Depending on the size of your cubes you might want to use a buffer pad on a Dremel but be very, very, very careful because the pad alone with nothing on it at all can melt plastic due to sheer friction. Another way would be to use a piece of window glass (larger than the cube's face) as a tool. Sprinkle the cerium oxide on it, spray some water over the powder, set the cube on top and go to work. You're probably going to find that the polish comes up in some places and not others because it's highly unlikely that the cube faces will have cast out as flat as the window glass you're using for a polishing tool. If that's the case you can either go to the bother of switching to an abrasive and grinding each face down flat on this same tool, using progressively finer grits until you're ready to try polishing again, or if the cubes are small enough you can work with the cerium oxide on a wet soft lint-free cloth and try the polishing by hand. It'll take a long while but it can be done. One other thing to watch for -- whether you're using a tool or a hand cloth, there's going to be a tendency for the cube's edges to blunt a little, ditto for the corners. Oh, and watch out for sticking if you decide to use a glass tool. If the cerium oxide dries out during the polishing it can be hard to separate the two bits, so keep it wet while polishing.

- Steve Richardson (former amateur telescope maker - well, just the one....)

"Jack" wrote in message news: snipped-for-privacy@posting.google.com...

we use the cerium oxide in slurry form, with a lapidary polishing tool that also keeps it wet. This is only the last of multiple polishing stages .Take a look at kingsly north or similar for lap tools. m

Cerium oxide WILL NOT WORK to polish plastic.

If you have a optical laboratory near you (one that grinds and polishes plastic lenses for eyeglasses) ask to buy a pound or so of plastic lens polish. It is basically tin oxide and aluminum oxide mixed together. It is super fine material, finer than cerium oxide.

Cerium oxide is glass polish. Tin/Aluminum oxide is plastic polish. Very big difference in surface finish.

Mike

oops! i missed the end of the subject line where plastic was specified. i was of course referring to polishing glass! m

What next? My glass firing schedules won't work for plastic?