Finishing tips

[Jmsteele187]

I need some tips for finishing my enclosures.  The first pedal I finished turned out great using enamel spray paint.  Every one I've done since has had some sort of defect after baking them.  The first issue I ran into I've solved.  My toaster oven was getting too hot, and made the finish spider web.  It actually looks pretty cool, if it's the look you desire.  The most recent one, even after taking every precaution to keep the enclosure clean between coats, has fish eyed all over.  I've sanded all the finish off, and started over.  But, I don't want to run into the same issue again.  Does anyone have any pointers for my?

[GibsonGM]

Clean the pedal with something like denatured alcohol or acetone when done sanding the unfinished surface (wear gloves, do outside in fresh air!!!!).  This gets the oil from your skin off, which along with any other oil, is causing the fisheyes.

Prime with metal primer...several light passes.    Smooth with 4-0 steel wool when dry.

Several light coats of your finish, not too heavy.  Build up the coats.    When dry/oven'd etc., apply several topcoats of clear, using the 4-0 wool lightly between coats, just to keep things smooth.

All done

[Jmsteele187]

Thanks.  I did use naphtha to clean it up before hand.  What I didn't do, is bake it between color, sparkle, and clear coats.  I'll try it and see how it turns out.

[Beo]

Wet or uncured coats underneath is what causes the upper coats to crackle and mess up. Thin coats dry much quicker. Toaster oven helps, but I've had some light colors darken when toasted.

I'm using an airbrush with acrylic paint these days. Much easier to work with and no smell... can do it inside! Just need a couple of good clear coats at the end.

Davent on this site has some great posts about working with acrylic paint and mediums.

[Jmsteele187]

The finish doesn't really crackle, as much as it separates into a web like pattern.  It almost takes on a reptile skin like texture.  It's kinda cool, if it's what you're going for.  That issue I've figured out.  The fish eye, and bubbling is driving me nuts.  It will look perfect before I bake it, but when I take it out of the oven it looks terrible.  Riddled with fish eyes and bubbles.  I almost just want to try and let it air dry for a week or two. 
Here's my process so far, if it helps.  Maybe I'm doing something wrong.
Sand enclosure, and clean with naphtha
Primer
A couple coats of color with ample dry time in between
A coat of metallic flake clear
A few few coats of clear
And finally, into the toaster oven to bake

[bloxstompboxes]

Make sure your multiple coats are thin coats. Too thick and the paint will fisheye. Also, make sure you sand the enclosure smooth beforehand. Any leftover shiny parts won't take paint well. You wanna rough it up a little but still be smooth. I use 100 grit paper. For primer, I have switched to rust-o-leum self etching primer. Works the best so far. Probably a good idea to preheat the oven before baking. And your baking you wanna do after EACH coat.

[Jmsteele187]

Make sure your multiple coats are thin coats. Too thick and the paint will fisheye. Also, make sure you sand the enclosure smooth beforehand. Any leftover shiny parts won't take paint well. You wanna rough it up a little but still be smooth. I use 100 grit paper. For primer, I have switched to rust-o-leum self etching primer. Works the best so far. Probably a good idea to preheat the oven before baking. And your baking you wanna do after EACH coat.

Other than baking after each coat, I've done everything you've mentioned.  I'll try baking it between coats, and see how it comes out.

[EBK]

I'm going to bump this thread rather than start another thread on the same topic.

I've finally fired up the toaster oven that has been sitting in my house for months.  Every instinct of mine tells me this is in no way safe:


Can anyone reassure me that I won't be cleaning up shards of glass from an exploding toaster oven door? 

[alfafalfa]

What temperature do you use in this oven ?

[bloxstompboxes]

I'm going to bump this thread rather than start another thread on the same topic.

I've finally fired up the toaster oven that has been sitting in my house for months.  Every instinct of mine tells me this is in no way safe:


Can anyone reassure me that I won't be cleaning up shards of glass from an exploding toaster oven door? 

It is safe if you adhere to some obvious guidelines in no particular order:

1. Use the oven only in a well ventilated area.
2. Don't leave it unattended.
3. Preheat before putting in your pedal, especially in the cold. I didn't do this and the temperature in the oven rose above the flashpoint of the paint vapor, before the oven's temperature gauge registered it properly. This caused some flame wooshes, doors popping open, and some actually cool paint effects with soot, but much swearing and near pants wetting.
4. Never again use this oven for the preparation of food. Ever!
5. Bake at about 150F, or maybe 50F less than the flashpoint of the paint you are baking dry. I think rust-o-leum's flashpoint is around 200F.

That's about it.

[EBK]

What temperature do you use in this oven ?

I'm taking some measurements with my multimeter now, trying to catch the high value of the cycle.

I do know that during preheat, it went over 100°C (212°F). 

Update: Looks like after preheat, the top of the heating cycle for the current oven setting is 70.7°C (159.3°F).  Perhaps this setting, plus sufficient preheating would work. 

[stallik]

Just in case, please setup a video camera while using it then stand well back. I don't want to see you or your folk injured but I really like a big bang

[PRR]

I cook pizza much hotter than I cook paint. The glass should be fine.

As said, even my pizza does not throw fumes like seared fresh paint. You really want to slow-roast, not flame-broil.

When done, build a tube guitar-amp in the toaster oven.

[EBK]

When done, build a tube guitar-amp in the toaster oven.

Can I skip the filament wiring on the tubes if I keep the toaster oven guts intact? 

[karbomusic]

The finish doesn't really crackle, as much as it separates into a web like pattern.  It almost takes on a reptile skin like texture.  It's kinda cool, if it's what you're going for.

I would be in heaven if I could repeat such things consistently. This was a happy accident and have yet to reproduce and I was standing right there when I did it for Christ's sake.



Moving on, "use thin coats" is often far thinner than most realize, a single coat does not mean fully covered visually. My main suggestion is to read the can carefully, as what's written on it is usually the most helpful other than 'thin' meaning thinner than many of us expect. IOW, sometimes "10 thin coats" means it took that many to fully cover what's underneath not, 10 coats where each one completely hides the previous FWIW. Too thin does run a risk of orange peel looks depending on paint used and other conditions FYI.

Ovens help curing, they do not magically absolve problems with super-thick coats where the user didn't allow the paint to fully dry between coats because each coat was too thick... This (below) happened 48 hours after the fact and after plenty of oven baking a couple days earlier... The top layer(s) dry and essentially become a paint can lid for underlying layers preventing them from drying/curing, baking often doesn't fix that and if it does, proper thin coats are still better...



As far as temps, based on the paints I've used roughly ~150-170F has been the most stable, going higher tends to raise the risk of discoloration etc.

[stallik]

That pattern looks like reticulation. It used to happen to photographic film when it went from cold to hot or hot to cold chemistry.
If it is the same thing, you should look at temperature variations to reproduce it

[vigilante397]

DUDE. THAT LOOKS SO FREAKING COOL.

[vortex]

It is safe if you adhere to some obvious guidelines in no particular order:

1. Use the oven only in a well ventilated area.
2. Don't leave it unattended.
3. Preheat before putting in your pedal, especially in the cold. I didn't do this and the temperature in the oven rose above the flashpoint of the paint vapor, before the oven's temperature gauge registered it properly. This caused some flame wooshes, doors popping open, and some actually cool paint effects with soot, but much swearing and near pants wetting.
4. Never again use this oven for the preparation of food. Ever!
5. Bake at about 150F, or maybe 50F less than the flashpoint of the paint you are baking dry. I think rust-o-leum's flashpoint is around 200F.

That's about it.

Extra safety...
6. Switchable power bar
7. Fire Extinguisher

[slashandburn]

I agree we the all the advice already given and only dropped in to mention that if depending on where you live it might be worth keeping an eye on the weather.  High air humidity can really f*ck you over if you're spraying outside, or even anywhere where you can't control air moisture levels.

I guess it depends where you live. In my neck of the woods the air regularly far to damp to make it a good painting day.

[karbomusic]

DUDE. THAT LOOKS SO FREAKING COOL.

I wish I could take credit for knowing how it's done that's for sure. I'd used that base coat/top coat combo plenty of times. It's Rust-Oleum white flat spray paint (IIRC), with Rust-Oleum Metallic Pearl Mist on top. It had happened before but I bailed and redid before I realized the beauty. I'm almost sure the light sanding I did to the base coat had something to do with it because it seems like the only time it occurred was when I did that base coat then tried to get it extra smooth with something like 400 grit before applying the metallic coat - I sort of tested that back then (this was summer 2014) but that one test didn't work.

I'll try again at some point where I can just concentrate on that test instead of building a pedal at the same time. I remember it "curling" right when the metallic coat went on. Thinking back, it's also possible I hit it with #0000 steel wool before painting - marking this all here for when I revisit.