What to do here? Painting Error

[exztinct01]

I have decided to perform my first attempt at painting a pedal enclosure using Bosny Auto Spray Paint. I watched the guide in youtube (zplanet videos).
So, I sanded with 180 grit, then with 800 grit, then washed the enclosure. After drying, I wiped it with a cloth to remove dust, then started painting gray primer. I did 5 coats of primer with 3 minutes b/w coats. One thing I noticed about spraying, if you always pass it on the same spots, only those spots are well covered while surrounding areas are painted thin. (I think I won't be able to express myself correctly here, English is not my main lingo).
Anyway, some paint rolled off the edge and I wiped it with a cloth which just messed the paint in that area. I sanded it with 800 grit dry and the surface became grainy and rough. I thought it would be covered though when I apply my colored paint but it doesn't fix anything (see photos below)

Here are other faces which are good enough in my opinion. Well, about the DC jack hole, I didn't have 1/2 inch bit so I tried to enlarge the hole with the bits I have, and that's the result. Anyway, it could still be covered with the jack.

[lukeferg]

Basically you have to sand that sucker until it's really smooth and then recoat.
Personally, I wouldn't bother with 5 coats of primer, 2-3 is plenty. All the primer does is allow your paint to stick to aluminium.
You might get a bit of an edge or line where you've got your sanded side and the rest of the box.
The other thing you could do is coat it with about a million extra layers of paint. Eventually it will smooth out, but that's definitely not the quickest or easiest method.
If it's just for your use I'd probably leave it. I've got some very questionably finished boxes on my board. It's what's inside that counts.

Also, to avoid painting the same spots I paint in different directions each coat. It means I get a really even finish

[bluebunny]

I'm with Luke: five coats of primer is about four too many!      On very rare occasions, I'll do two.

[GibsonGM]

Prime only until the box is covered, not too much!   We often feel that more paint or primer on something is better...it's not!    Too many layers can lead to "delamination", where they begin to peel!

You can try to sand the 'orange peel' down one more time, and top coat it again - that would be ok.   Then clearcoat.    I would not do much more than that, however.    Also, you can get this "orange peel", also called "Stippling", if the can is held too far away, and runs if it is held too close, and it is also a problem if the can is not shaken for a long enough time.

Practice!!   

[lukeferg]

One thought. Any reason you were sanding with 800 grit? I use whatever grit I have on hand. By sanding with 800 before applying paint you are reducing the tiny grooves that the paint really likes to stick into. Some people recommend all sorts of different sanding regimes to get a perfect finish but these are usually when dealing with a raw material, not a painted finish. Those tiny grooves that 180 will leave will be completely filled with paint and you'll never see them by the time you've put 10 coats on it. If you're having problems with drips then thinner coats will help, don't feel you have to get it painted in one go.

[strungout]

First, you've got some good advice already.

Second, don't worry too much, there IS a learning curve to it. I've only painted one box so far and didn't use primer, and emptied the whole can trying to get it right, re-sanding some ugly parts, paint drips, bugs (was doing it outside - I think one is still lock in between layers...), I did the 'wiping it with a cloth thing, forgetting that I would probably leave lint on it...

But I ended up doing a decent job, so keep at it!

[Les Paul Lover]

A light sand and respray should be fine.

Don't forgot too that thw clear varnish will pretty much melt the colour you put on too, so that the lower paint surface will look a lot better once varnished.

In any case, once you get your finish spot on...... You will damage it quite easily. It will get marks. So try not to worry about it too much.

I will consider powder coated box for my next builds, un the hope thw finish will be more durable.

[exztinct01]

Thanks for all tips.
I might consider buying a spray with wider coverage so as to have a more even finish.
So that every single pass will cover the whole area I'm painting.
Anyway, how bout clear coating? Any suggestions how many coats should I make?

[PRR]

> pass will cover the whole area I'm painting.

Stand back further.

You WANT 90% of the solvents to evaporate before the spray hits the surface. Spraying too close is bad.

[Keeb]

Your picture reminds me of what happened when I sanded some filler/plaster before i set completely.
My pedals never have a perfect finish and I'm fine with that since they're only for me, but I want to ask a couple questions your post made me think about.

• If you sand before the paint has completely dried, could it "flake" the partially dried paint?
• Can the solvent in the paint soften the primer and require more time to dry?
• Could this be what happened here? The paint dissolved the primer and the sanding flaked the primer and paint?

[lukeferg]

• If you sand before the paint has completely dried, could it "flake" the partially dried paint?
• Can the solvent in the paint soften the primer and require more time to dry?
• Could this be what happened here? The paint dissolved the primer and the sanding flaked the primer and paint?

1. Yes, and you'll probably put all sorts of streaks and paint bits everywhere and make a real mess of things. Generally, when painting metal you shouldn't need to sand between coats. If you get a bug or dust in it then that's different. If I sand a painted surface I'll wait at least 48 hours before sanding but often up to a week. It's time consuming but important.

2. It depends on what base your primer is made of. If you have the same base as your paint then definitely. I've used rustoleum paint in the past and that is really finicky regarding recoat and drying times for this exact reason.

3. Possibly, but I think it's more a case of that the surface wasn't prepared as well as it could have been. It does make it even more likely whe you consider how much primer was used, some of the primer wasn't dry yet and sanding ripped it up. You can also get a reaction if the paint hasn't cured properly. With rustoleum, you have to recoat within 1 hour or let it dry for 72 hours before a recoat. If you try and differ from this (and trust me, I have) then you'll end up with a disgusting cracked mess that looks like the surface of another planet and lifts off whatever your painting. Another paint brand may have a reaction similar to what's happened here.

[lukeferg]

Thanks for all tips.
I might consider buying a spray with wider coverage so as to have a more even finish.
So that every single pass will cover the whole area I'm painting.
Anyway, how bout clear coating? Any suggestions how many coats should I make?

Better quality paint will have more 'paint bits' in it. That's what your paying for, so that means better coverage with less coats. It usually also means the paint is thicker and so you don't get as many drips or runs.
Do as many light coats as you feel you need. I would do no less than 6 if you want you pedals to have a remote chance of looking decent after a gig. Often I'll do 10. They're going to chip on corners and edges, the only way to stop that is powder coating. By using lighter coats you reduce the chance of drips as well, particularly on vertical surfaces. If the surface is flat then I lay it on a bit thicker.
If you want better coverage then spray in different directions. Eg. Across, up/down, diagonal, haphazardly. That way you get the bits that other directions miss

[digi2t]

Ummmm.... how warm was it when you sprayed it? Too warm will tend to air dry the paint before it has time to flow out, thus the pebbling effect. Sometimes, if it's really warm, the droplets of paint are fairly dry even before they hit the surface. Generally this problem spans between mild (orange peeling), to wild (pebbling). Either way, start sanding. 

[davent]

Either way, start sanding. 

Wet sanding.
dave

[Mark Hammer]

Ummmm.... how warm was it when you sprayed it? Too warm will tend to air dry the paint before it has time to flow out, thus the pebbling effect. Sometimes, if it's really warm, the droplets of paint are fairly dry even before they hit the surface. Generally this problem spans between mild (orange peeling), to wild (pebbling). Either way, start sanding. 

Damn weather!  Damn global warming!

The chassis looks pretty much like every 2nd box I've ever painted.  The spaces we have available to us for spraying (with adequate ventilation) are often impacted on by weather conditions.  My garage can get bloody hot, and can also get bloody humid.  Some spray paints cope well with those conditions, and others not so much.  I find that "engine paint" often gives optimal results in my own painting environment.  If I had a proper spray booth with a fan+vent system, I suspect my choices could be wider.

[digi2t]

Either way, start sanding. 

Wet sanding.
dave

Yes, absolutely. Thanks for that precision Dave. It slipped past me.