I know there's a fair number of you...
Do you folks sand the enclosures before you coat? How deep a ding is too deep to cover up? How rough can the metal be and still be covered acceptably by the powder?
It depends of the enclosure quality. Most of the time, I use 320 or 400 and a quick pass of 600.
Can you make it too smooth to the point it wouldn't take powder? Are some scratches actually beneficial?
I usually don't sand, just degrease and prebake. If I do sand, it's sandblasting so I get a little tooth but no scratches. A lot depends on the powder, how thick it builds, opacity, etc. I think some very fine scratches can help adhesion but bare cast aluminum should have plenty of pores so it's probably a wash.
I was told that sandblasting aluminum is a big no-no, as the aluminum is so soft that the sand actually embeds itself in it and comes to surface during baking to ruin the finish? Nutshells and glassbeads may be a different story, though. Or I could be completely misinformed on that.
Not that I have the sandblasting facility anyways... ::) I'm looking to set up some powdercoating in extremely unfavorable conditions so I'm trying to remove as much of the guesswork and trial and error from the process before I get going. Where I live we don't have garages or basements. ;D
Quote from: muddyfox on April 12, 2014, 02:53:25 PM
Can you make it too smooth to the point it wouldn't take powder? Are some scratches actually beneficial?
Try to avoid scratches or it will appear through the coating.
Are we talking serious gouges or something left behind a 150grit paper?
I'd suggest not to go under 220
Quote from: muddyfox on April 12, 2014, 04:03:25 PM
I was told that sandblasting aluminum is a big no-no, as the aluminum is so soft that the sand actually embeds itself in it and comes to surface during baking to ruin the finish? Nutshells and glassbeads may be a different story, though. Or I could be completely misinformed on that.
Not that I have the sandblasting facility anyways... ::) I'm looking to set up some powdercoating in extremely unfavorable conditions so I'm trying to remove as much of the guesswork and trial and error from the process before I get going. Where I live we don't have garages or basements. ;D
That can happen, but you can also wash and scrub the part degrease and prebake. A worse issue is that softer grades of aluminum with thin walls can erode through. I sandblast Hammond boxes frequently enough but with wash/scrub/degrease it hasn't been an issue.
Again usually I just degrease and prebake. Sandblasting only parts I've stripped, to be recoated.
I only sand if I'm doing a transparent/candy finish.
I only sand if a clear/transparent as well. I prebake however and clean with acetone until no more black stuff comes off. So much easier than painting anyday :)