Question on painting

[dacaumodo]

I know it sounds dumb, but do you HAVE to paint enclosures, I mean, would an unpainted aluminium enclosure get oxidized with time? I asked the same question about inside, but I'd like to know for the whole enclosure.
I quite like the raw look of Hammond boxes (and I'm lazy, too)
thx
g

[petemoore]

I know it sounds dumb, but do you HAVE to paint enclosures, I mean, would an unpainted aluminium enclosure get oxidized with time?
  Seems like they're oxidation resistant? I saw a polished aluminum boxes recently...looks real cool.
   I asked the same question about inside, but I'd like to know for the whole enclosure.
  Functionally I see no need to paint aluminum for stompobox use.
I quite like the raw look of Hammond boxes (and I'm lazy, too)
  Yupp..but I like markings, [I have no aluminum enclosures] and I like hand painting, so I paint and use the paint to mark them, I have a motif' thing happening on my pedalboarded pedals...

[jonathan perez]

pour salt water on the top of the enclosure and let it sit for a while.

[dacaumodo]

Excellent. Thanks Pete.

[Moonface]

pour salt water on the top of the enclosure and let it sit for a while.

WTF this will do?

[ildar]

pour salt water on the top of the enclosure and let it sit for a while.

WTF this will do?

Oxidize and etch the aluminum.

[JimRayden]

pour salt water on the top of the enclosure and let it sit for a while.

WTF this will do?

Oxidize and etch the aluminum.

Ooh, I bet this'll look bad (in a good way). Anyone got an example pic?

----------
Jimbo

[Meanderthal]

 I used to paint them with bad results- mine always had a brittle easily chipped finish. I tried baking, blow dryer, slow cure, all the usual stuff. Then I saw the ones at GGG with the brushed aluminum look and really liked that! So, now I just hand sand them for an approximation of that look and clear coat them with automotive lacquer. Nice clean almost manufactured look! And durable too.

[petemoore]

Use a flat sandingpad [piece of plywood, maybe some newspaper or better padding] with a vertical backstop guide.
  When sanding, use the guide and be very careful to NoT rotate or come off the guide at all, even 1 stroke of off axis sanding can take a whole lot of sanding to get back to all straight lines.
  That's a cool look and probably holds clearcoat quite well.

[dacaumodo]

Use a flat sandingpad [piece of plywood, maybe some newspaper or better padding] with a vertical backstop guide.
  When sanding, use the guide and be very careful to NoT rotate or come off the guide at all, even 1 stroke of off axis sanding can take a whole lot of sanding to get back to all straight lines.
  That's a cool look and probably holds clearcoat quite well.

Thanks. I didn't think of the backstop thing.

[Mark Hammer]

All my painting is done in the garage, which is bloody cold some 7 months of the year (or at least cold enough to risk condensation on the chassis), and which also houses one of our fridges plus our freezer and connects directly to our kitchen table via a doorway.  Needless to say paint fumes are not appreciated in the kitchen, so when the seasons dictate the garage door staying shut, paiting comes to an abrupt halt.  That's the long way of saying painting is a nonstarter for some folks.

The finishing is partly a function of how obsessive you are about lthe appearance of the legending, and what you're going to legend with.  Some folks are pretty informal about their legending.  JC Maillet (viva analog) makes some terrific and complex boxes, and most of his stuff is Sharpie pen on an unfinished Hammond box.  For a lot of folks like me, legending consists of rub-on transfer lettering, which is going to be black.  To be useful as legending, black needs to be against a much lighter background.  To the degree that this requirement restricts your colour choice, many functions will just say to heck with it, and use black lettering on a bare aluminum box because it shows up, and does so with less work.  Others will buy powder-coated boxes in light colours and use that for their black lettering.  Either way, rub-on transfers tend to rub off in the absence of a clearcoat of some kind.  I've used matte (satin) finish clearcoat on top of painted surfaces and it doesn't look half bad, but I've never attempted it on top of bare aluminum.  Might look okay, might look like crap, might look great if the surface is prepared in some manner.

[dacaumodo]

I used clearcoart directly on aluminium twice. The first time it turned out alright, the second time, strangely enough, it turned out cloudy (that my best description) and full of tiny bubbles. It might have to do with the fact that I let it dry in the open air, under the garden plastic table (in case it rained)...
I think I'll go the bare aluminium for a while, unless I find someone to do my painting for me around here (I'm thinking perhaps an auto mechanic buddy of mine might know a car painter or two...)

[Meanderthal]

 Don't worry much about being cloudy- that'll clear up as it cures. I think that's just humidity. Couple weeks. The bubbles won't go away.
Try several light coats a few hours apart ... I had to learn that the hard way.
My problem with this is I'm too impatient, I kept trying to do it with one coat! I learned that when the can says "for best results" they really mean it!
Another trick I learned- do the enclosure first, then start to solder(provided you're sure the circuit is something you really want). The enclosures look better when I do that.
I have a couple prepared with sanding and clearcoat also- waiting for holes... for future projects that I don't know yet if they're boxworthy.

[jonathan perez]

i think it also depends on the gloss you use. the thinner cheaper kind does that. but the thicker, rustoleum stuff works GREAT! and dries faster.

[dacaumodo]

i think it also depends on the gloss you use. the thinner cheaper kind does that. but the thicker, rustoleum stuff works GREAT! and dries faster.

Mmmh... I've gotta look into this.

[ildar]

I always chime in on the painting threads with this: make sure your primer, color coat(s) and clear coat are all compatible. Even if they are all from the same manufacturer, don't assume they are compatible.

[markm]

Don't worry much about being cloudy- that'll clear up as it cures. I think that's just humidity.

Very true.
Some paints will cloud easier than others.
It is humidity or moisture in the paint that causes clouds.
A slight blast from a heat-gun or hairdryer will take the moisture right out of the paint + heat actually make the paint spread a little
bit making for a smoother finish. Body shops use heat lamps for this as well as speeding dry time. I'm not saying to bake it with the heat gun, just a little blast.....maybe 30 seconds or so heating all surfaces of the enclosure. One of the things about aluminum is that it conduct heat easily.

[Paul Perry (Frostwave)]

would an unpainted aluminium enclosure get oxidized with time?

Not if you keep it dry.
I have gear 50 years old in plain aluminum boxes (stuff rescued from labs etc).

[dacaumodo]

would an unpainted aluminium enclosure get oxidized with time?

Not if you keep it dry.
I have gear 50 years old in plain aluminum boxes (stuff rescued from labs etc).

Thanks, that's the kind of hindsight I don't have (yet)!

[ildar]

Not if you keep it dry.
I have gear 50 years old in plain aluminum boxes (stuff rescued from labs etc).

It's very possible that this aluminum either isn't aluminum at all (stainless steel), or has a lacquer finish. Untreated aluminum will oxidize over time, simply from atmospheric conditions, not necessarily from getting wet.