Sandblasting

[waterzap]

Planning to clean my valve covers. Repaint and reinstall. What is the best way? Sand blast? Soda blast? I heard that sand blasting can warp metal, though for something small like valve covers, its probably ok. Also read that sometimes paint comes off after soda blasting. So not sure. I have tried with wire wheels before, but that leaves gashes in the metal. Is Soda media reusable like sand? What about walnut shells?
Just bought a 20 gallons compressor to replace my small pancake one. Prob wont work to sand blast a car, but should be ok for small jobs

[Steve Passmore]

With your small compressor and I guess a small blaster that will do the job fine with sand. You will not create enough pressure to warp metal. Small compressors get up to about 150lbs whereas professional blasters will get 1500lbs thats when the metal distorts.

[waterzap]

Yes, the compressor wont do much over 125 psi. And it doesn’t really matter to me if it takes me a while to do. Just want to clean it up nicely. I can do it in the driveway on a piece of tarp and just recover the sand afterwards

[Hilarius]

Steve is right, but I'd prefer glass beads as the blasting medium.
Have lots of very good experiences with that for frames as well as for sheet metal and other smaller items. See picture for whole body.

[waterzap]

Thanks. Just read that glass does take longer, but it wont deform the metal like sand can. Also works better on lower pressures.
Anybody ever use this?

http://www.ati-blackdiamond.com/

[Scot Minesinger]

After the rust is removed it may be pitted.  This has definitely happened to me.  If you prime and repaint, they look terrible all painted over pitting, especially considering the labor to remove, remove old gasket material, blast and re-finish.  By the way this is an ideal powder coat application.

You cannot fill the pits with bondo.  The only solution I have found that works is to apply many coatings of the high temp paint or powder coat and let the finish actually fill the pits.  Then sand and re-coat as necessary.  This takes a while, but looks great when finished. 

Don't forget the bolts that hold the valve cover down.  I can't tell you how many times I have seen repainted covers fastened down with rusty crummy looking bolts.  they can be blasted and powder coated Cadillac blue.  The powder coat blue bolt finish will survive the low torque on the bolts.

Same method for oil pan (except it will not fit in my oven), and other engine parts.

This is a true labor of love.

[R Schroeder]

I sand blasted mine 4 years ago and they are still nice. I did NOT prime first. I just painted them. Engine shots are recently taken.
Roy

[Tom Boehm]

Hello, I have a lot of rust pitted parts on my 1940 Lasalle. After bead blasting I prime the parts with high build primer. You can get it in a spray can at a place that sells auto paint. If the pitting is severe I spray several coats on and then wet sand the surface smooth. The primer is intended to sand easily. The primer fills in the pits. After sanding everything smooth spray on one final coat of primer. Tom

[grandads59]

I use the multi coat and sanding routine and they look great.

[Jeff Rosansky CLC #28373]

Just did my valve covers last month.  With the size of them, I just used sandpaper.  It didn't just get the paint off but it helped with the pits too.  Think I de-greased them for about an hour tho.
Hi temp primer that I sanded and then the final paint.

Yes Scott, I did the bolts too.
Jeff

[greybeard]

Tom is right.  I just finished my valve covers. I used Black Diamond in my sand blast cabinet with mixed reviews.  It works well but tended to plug up the siphon tube.  I like sand better. I've used glass on aluminum parts and they turn out beautiful. A word of caution: Use a respirator, the dust can be hard on your lungs, especially the glass.  As sealed as my cabinet is, I still get dust filtering out.  A vacuum attached to the cabinet make a huge difference.  I would recommend wiping down the raw metal with "metal prep" in case there is some rust in the pits.  Apply several coats of high fill primer, sand smooth and then wipe them down with grease and wax remover before applying the final coat.  Poke the bolts through a piece of cardboard so only the heads show and painting them will be a breeze.
Good luck with your project.

Don Sylvia

[Jeff Wilk]

Glass beading is the way to go but it will remove all the rust too which is what you want but don't be surprised if you do find pitting on some spots of the covers especially if they were not oil soaked.  I did this on our entire front end and all engine components and then sprayed with etching primer and the valve covers with Bill Hirsch  blue engine paint which looks awesome .  To be safe I used three top coats which filled in the only minor pits I had on the rear edge.  The beads are reusable too but MAKE SURE you wear a respirator like greybeard said.  You have no idea how fine a powder is thrown off even from inside a blast cabinet.  So if you are doing it on a tarp, the dust will be everywhere.  Any nearby neighbors to be mindful of too just in case........have fun.

[Wayne Womble 12210]

With your small compressor and I guess a small blaster that will do the job fine with sand. You will not create enough pressure to warp metal. Small compressors get up to about 150lbs whereas professional blasters will get 1500lbs thats when the metal distorts.

I dont want to be anywhere near a sandblaster that operates at 1500 psi. Large sandblasters that I have used and been around operate at a more normal 100-125 pressure. The difference is the volume it is capable of. Like most things the results of sandblasting lie more in the skills of the operator than the equipment. You can use a large sandblaster and do delicate work if you know what you are doing.  I have done many corvettes without any damage to fiberglass and that was with a large commercial unit.

[Jim Stamper]

     I have used glass beads in my blast cabinet for more than 15 years. If it comes off and apart and will fit in the cabinet it gets beaded, etch primed and painted.
   
    Sometimes, when doing fabrications such as the welded up brackets on an oak push cart I made recently, I get a bit anxious and think I can get something done before the paint cures if I am careful.  I totally messed up a painted piece and then thought about the Eastwood Powder Coat outfit I had never used. It seemed like a lot of prep and effort. I beaded the piece again, read the directions and powder coated the piece in a toaster oven, too small to be practical, but it worked for this job. In less than an hour from back in the cabinet to cooled powder coated part, ready for what ever abuse I could give it. My" takes too long" thinking about powder coating was completely out the window. Counting paint curing time the powder coating is many times faster than painting.

                 Jim Stamper;   CLC#13470