Guest imported_jmarsicano Posted March 19, 2005 Share Posted March 19, 2005 Ok gang...I have a cast aluminum pair of valve covers. When I got them you coundn't see the fins due to 30+ years of grease...grime...insert your ugliest scenereo here...I put them in my nice new glass bead machine and they now look like they day they were cast, really nice, not a spec of dirt on them.Now... what comes next? They have a gritty feel to them and have a dull finish. I am sure you all know what something looks like after its glass beaded or sand blasted. I dont need them to look like chrome, just a clean finish. Do I polish next? And if so... what do I polish with? Any specific polishing compounds to use or stay away from? What would you use if you had a nice size budget/well equiped garage to finish these off?Is it the same as polishing stainless trim? O lord, too many questions in my head.Do I get a trip to the hardware store for some new tools/stuff for the garage... Cause all I need is a good excuse to go!Any help is appreciated! Thanks!Joe Link to comment Share on other sites More sharing options...
heidigirl Posted March 19, 2005 Share Posted March 19, 2005 if you want an 'as cast' finish, paint them with a clear coat that has a bit of flattener in it. the bead blasting provides a perfect tooth for the paint, and the paint itself will smooth out the gritty feel of the castings. Link to comment Share on other sites More sharing options...
Peter J.Heizmann Posted March 19, 2005 Share Posted March 19, 2005 Hi, Joe...Aluminum is extremely porous. Many years ago, we used to pour 319 aluminum corner castings for straight truck cargo bodies. Our customer requested what could be done to brighten the finish on them, especially, for regrigerated bodies. Cast aluminum will oxidize in time and the finish becomes a dark gray.Well, we polished some to show how it opens up "pits". Not pretty.As you stated, you are not looking for a polished/chrome look. Try buffing very gently to even out the gritty finish. As I have never had case experiences with painted finishes on aluminum, I cannot contribute on this scenario.I feel confident folks will submit their knowledge shortly.Regards,Peter J. <img src="http://www.aaca.org/ubbthreads/images/graemlins/grin.gif" alt="" /> Link to comment Share on other sites More sharing options...
Guest imported_PackardV8 Posted March 20, 2005 Share Posted March 20, 2005 Don't use blasters. Use a BRASS bristle wire brush preferably under power. Link to comment Share on other sites More sharing options...
nearchoclatetown Posted March 20, 2005 Share Posted March 20, 2005 Or ground walnut shells, Joe, they clean without putting a texture on aluminum. Link to comment Share on other sites More sharing options...
Guest imported_jmarsicano Posted March 20, 2005 Share Posted March 20, 2005 Well, it was my first attempt. I did glass bead them already, so that damage is done. They look good sitting on the bench, just have that gritty feel and I know as soon as dirt hits them it will stick. I may try a little light buffing. Not sure. nearchoc- I tried to find wallnut shells, but no one in our area seemed to have them or could get them. Link to comment Share on other sites More sharing options...
DizzyDale Posted March 20, 2005 Share Posted March 20, 2005 Dear Joe,FIND someone with the shells as described,smoother not so porous,it will be WORTH it.DO NOT polish,you will make a mess ,besides its NEVER ending.DO NOT paint em either,General Motors did not feel the need to paint em WHY should you?IMHO.diz Link to comment Share on other sites More sharing options...
Guest imported_PackardV8 Posted March 20, 2005 Share Posted March 20, 2005 the brass wire brush under power will work fast. Link to comment Share on other sites More sharing options...
nearchoclatetown Posted March 20, 2005 Share Posted March 20, 2005 Joe, McMaster-Carr has everything you need in life. Or you can borrow mine, if you want to test them. Link to comment Share on other sites More sharing options...
ronbarn Posted March 21, 2005 Share Posted March 21, 2005 Grainger also has them. McMaster and Grainger both have on-line catalogs.For older (and I mean much older than 30 years), the natural finish of the cast part is normally correct. Polished aluminum looks "neater" but is generally not needed. Link to comment Share on other sites More sharing options...
Guest imported_jmarsicano Posted March 21, 2005 Share Posted March 21, 2005 Thanks everyone!Good tips all around. I will put you all in for a pay raise!Joe Link to comment Share on other sites More sharing options...
Rich Niezabitowski Posted March 21, 2005 Share Posted March 21, 2005 Here's what works for me on a cast magnesium wheel that has been machined to roughly an 80 RMS surface finish. I start by using some of the wheel cleaner supplied by Griot's garage and clean the oxidation up using a white scotchbrite pad. Come out smooth "as machined" but not shiny. It will accentuate the pitting but the wheel cleaner cleans the pits out pretty well. You can polish it up from there, but in this case yoiu don't need to. I think i would have bead blasted with a less agressive material at a fairly low pressure which works very well on aluminum carburetors and manifolds. Link to comment Share on other sites More sharing options...
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