I am back from my road trip.
We use a vibratory tumbler system do restore all amuminum parts. This gives you the best results and will last the longest in appearance too. Once they're restored, you only need a can of syray brake clean and a paper towel to clean them. Just wipe them down every once and a while. That is the other great part of having valve covers restored by us. Very easy maintainance for years to come and they will look perfect for a long time. And the price is very reasonable in today's world of $3.00 a gallon gas, $95 plus shipping to restore a pair of any small block valve covers.
I should also point out that when parts are glass beaded, they look good for a very short time. Dust, dirt and finger prints will stick to the parts because the media disturbs the original petina of the surface. Even using scotch brite pads and steel wool will not correct these issues or make them whole again. We have done thousands of valve covers over the years and never had an unsatisified customer. Our process is also NCRS accepted. We actually restore more Corvette valve covers than we do Camaro covers!