sand blasting

[monster01]

hey im gonna be powder coating aluminum. Right now its anolized so i would need to strip that before i coat it. Would i use anolize stripper or would i sand blast it? If so what grit? Also, what size glass beads would i need to clean it with?

[non-stick]

ummmm.... I'll be honest here. I'm sure there's a chemical to take off anodize I just can't re-call what it is off the top of my head. Maybe Caswell can suggest something. As far as surface prep.... glass bead is great stuff for surface modification, but not prepration in my book. The glass "dimples" the surface if you will. Not really digging in like an oxide (garnet) will, and not providing you with as much grip, basically. I'd strip the part of it's anodize. Get all out of the corners,blah blah blah. Then I'd hit with a nice low pressure grit blast if possible. I've used glass bead on almost everything and I've found it's good for unfinished parts. It takes casting "flash" off and smooths out uneven surfaces,etc. But the grip? Oxide blast is better. Actually...it's one of the best methods of surface prep you can do for adhesion truth be known. After that, yes...I'd do the glass bead method. While not perfect, you'll still get good grip with it and lastly, I'd do the sand-paper scuff. All of these methods incorporate a solvent washdown,however. No matter how good you blast and even if there was no oils or greases to begin with, the blasting media always carries a "dust" or can be impregnated with oils from past parts and you're basically pounding the part with it. Hope this helps....Russ

[GramSlam]

There is a chemical that can take care of the anodized layer. Caswell's Anodize & Chrome Stripper. But if you are in a hurry you can use Drano powder. Be sure you get the powder Drano and verify the ingredient is Sodium Hydroxide (LYE).
If you do go with the Drano, be advised it does not have any inhibitors in it like Caswell's stripper. So you will need to keep a close eye on the part to make sure you don't strip the aluminum as well. Use a multi-meter to check for continuity of the part. Anodized aluminum will not conduct electricity, so when you hear the beep, which means it’s done.
Also, watch out for the fumes, they are not deadly, but can induce an asthma attack in asthmatics.


Hope that helped ;o)