Powder Coating Tutorial and Discussion

[John Lyons]

I don't think it matters how rough the box is as far as the powder sticking.
There are a number of transparent powder colors and
clear top coats that are for highly polished metals like car rims etc.

Yeah, the unbaked red does look like a Foxx pedal.

john

[Auke Haarsma]

Thanks John for this well written tutorial!
I am tempted to give this a shot

[DougH]

Nice tutorial!

I don't do all the baking steps and etc to clean the box. I just basically clean it real good with acetone. I have been applying the powder coat with the box on the oven rack, then pick up the whole thing and stick it in the oven. I ground the rack when doing the coat. That works well except 1)the rack builds up powder that needs to be sanded off after every 2 or 3 times and 2)it's easy to miss the bottom edges of the box.

So I've made some "hangers" out of coat hanger wire. They get inserted into the lid screw holes on the box and they can be used for the ground too. I'm going to try hanging them (on an outside clothes drying rack) to apply the coat. This will allow better access to all the sides and edges of the box. In fact I'm going to try powdercoating the inside of the box too. Then I will pick them up by the hangers and hang them inside the oven for baking. I'll see how this goes, it's definitely an ongoing learning process.

[PerroGrande]

Hi Doug,

Acetone is a great way to clean these boxes prior to coating.  If I get a part that is loaded with fingerprints, etc, I'll start the process with acetone.  I still do the baking steps, however, as I've traced most of the problems I've had to moisture.  Even after an acetone cleaning, I've experienced some bubbles in the powder coat caused by moisture working its way out. 

re: edge coverage...  Yep.  Glad to hear I'm not alone in that regard!!   I tried several alternate ways of supporting/grounding the box prior to using the hook method including using the oven rack.  I did several boxes where I put them on a piece of grounded PCB stock.  The results were okay, but getting coverage on the sides was always an issue.  Even when I thought I had it covered well, it wasn't.  It would look okay, so I'd bake it.  It would even look okay in the oven... but... when exposed to bright light, the coverage got noticeably lighter as it went toward the bottom of the sides. 

In surfing a variety of forums on powder coating, I noticed that nearly everyone suspends the part in some fashion. Many of the "real" powder coating ovens (and home ovens that have been re-purposed for the task) suspend the part throughout the baking process.  In some cases, the unit that holds the suspended parts during the painting process slides right into the oven for baking.  So I think your hanger idea will work out great. 

When I switched to the boxes dangling, all the coverage problems on the lower portions of the sides went away.  The tricky part is getting the box back OFF the hook without damaging the powder, or having the box fall while tilting to cover the bottom panel!    

[DougH]

Yes, and it's definitely important, as you have expressed so well, to practice all your "moving" steps before applying the finish.

BTW, I was able to re-do a couple early boxes I screwed up. I used a palm sander with some really heavy grit (can't remember the number right now) sand paper. Took about 5-10 minutes but I was able to get the old powder coat off and start over from scratch.

Another thing I found that helps me is to not drill the boxes first. Then I don't have to worry about build-up in the holes. I apply the powder and cure it first. Then (after a day or so to set and etc) I completely cover the box with painters tape and drill it out. The tape keeps the finish from getting scratched from metal filiings when drilling. After vacuuming up all the filings around the work area I remove the tape. The light adhesive from the tape can dull the finish slightly, but a damp cloth cleans it right up.

BTW, thanks for the tip about not touching the box once it is prepped. Skin oil may have accounted for some of the "sticking" issues I had that I couldn't account for. I'll use a cloth to handle it from now on.

[Gus]

What about teflon screws in the four corners to hold the box off the tray?   I understand you would need four pads for the screws.  High temp and the powder coating should be removable.   One might have to turn and thread the teflon on a lathe to make the screws. 

[DougH]

That would probably work, Gus, but the way I had it set up I grounded the oven rack. So the box needs to make electrical contact with the rack in my case. This way I avoid connecting the ground clip directly to the box, removing it to shoot that part, and then hoping the powder sticks (doesn't work real well, I've tried it).

[The Tone God]

What about teflon screws in the four corners to hold the box off the tray?...One might have to turn and thread the teflon on a lathe to make the screws.

Or you could use normal slightly longer #6-32 screws that fit in the case holes and wrap some of the thread with the high temp tape like what came in the kit. When the screws are tightened the tape will push the lid against the case making the ground connection to accept powder. This will also make sure the lid will mate properly with the case after curing the powder. The case screw threads will be preserved so no clean out will be needed. The tape won't stick to the powder coat so removal will be easy. The screws will elevate the lid/case off the resting surface during curing preventing mess up with case movement. You will need a flat solid surface to lay the box out on to cure like say the tray that comes with the toaster oven or a piece of thin metal you cut to fit.

BTW, I was able to re-do a couple early boxes I screwed up. I used a palm sander with some really heavy grit (can't remember the number right now) sand paper.

Or you could use some paint stripper. I recommend Circa 1850 "furniture stripper". A few bucks for a tin at a home renovation store. Brush it on the whole case thick and keep brushing on areas that go a matte "dry" look. After about 30 seconds the coating will bubble off the case and you can peel it off like plastic skin. If there are any areas that still have coating just reapply stripper and wait another 30 seconds and it should come off. Very quick and easy. I have only tried this on poly based powders.

WARNING: Use in a well ventilated area, wear glasses/goggles, and wear at the very least latex gloves if not chem gloves. (the stripper will go through many other types of gloves including nitrile). Be near a water source to wash the case and yourself if needed.

Another thing I found that helps me is to not drill the boxes first.

I would not recommend that. The powder coat can chip off the case, even with the tape applied, which will force one to go through the above stripping procedure. How do I know ?

BTW, thanks for the tip about not touching the box once it is prepped. Skin oil may have accounted for some of the "sticking" issues I had that I couldn't account for. I'll use a cloth to handle it from now on.

Once I do my wipe down on the boxes naked hands never touch the case again. I usually wear a thin disposable glove type like latex or nitrile to handle cases after that point.

Andrew

[PerroGrande]

For my flub-ups (and there were plenty!), I started with various sanding methods...  This produced double frustration -- not only was the powder coat bad, but then I had to go through all the work to sand it... 

I now use this stuff:


I found that if I have a flub, I lightly sand the entire box with 220 (or so) grit paper until the finish looks "matte" all over.  A few minutes of immersion in this nasty stuff takes the powder right off.  I'm eager to try the Circa 1850 Furniture Stripper, though.  A little bottle of this stuff cost 20 bucks... 

Oh -- if the box has been clear-coated with traditional methods, it slows this stuff down dramatically.  Again -- reason to check out the furniture stripper.  Thanks for the tip!   

[DougH]

Another thing I found that helps me is to not drill the boxes first.

I would not recommend that. The powder coat can chip off the case, even with the tape applied, which will force one to go through the above stripping procedure. How do I know ?

I haven't had any problems with that when using a drill press. The holes come out real clean.

I now use this stuff:

Ah, I didn't realize Eastwood carried that sort of thing. I should go back and read the catalog...

I'll have to get some of that stuff, thanks!

[PerroGrande]

The Eastwood stuff is nasty, and works like a charm.  However, I'm very eager to try the stuff Andrew recommended, especially since he mentioned that it was relatively cheap.  The stuff that I bought is actually a little pricey.  It *is* reusable, but I'm not sure how long it will last in practice.  I've only used it a couple of times thus far.

[jimmybjj]

What about teflon screws in the four corners to hold the box off the tray?...One might have to turn and thread the teflon on a lathe to make the screws.

Or you could use normal slightly longer #6-32 screws that fit in the case holes and wrap some of the thread with the high temp tape like what came in the kit. When the screws are tightened the tape will push the lid against the case making the ground connection to accept powder. This will also make sure the lid will mate properly with the case after curing the powder. The case screw threads will be preserved so no clean out will be needed. The tape won't stick to the powder coat so removal will be easy. The screws will elevate the lid/case off the resting surface during curing preventing mess up with case movement. You will need a flat solid surface to lay the box out on to cure like say the tray that comes with the toaster oven or a piece of thin metal you cut to fit.

Sorry to revive such a old thread. In the method described by Tone God in the above quotes, would the enclosure seal itself shut?

[The Tone God]

Sorry to revive such a old thread. In the method described by Tone God in the above quotes, would the enclosure seal itself shut?

There is alittle bit of crossover powder at the lid and case so the two parts will be fused together but its weak. You can either pry it the lid off through one of the lid holes or my favourite method is to take a driver of some sort like a nut driver, run it through one of the machined holes like a pot or switch, then give the lid a good tap from the inside. The lid will pop right out with a clean seam. I suppose if you want to be really safe you can run a knife around the gap to cut the powder but I haven't had any problems with this issue yet.

Andrew

[jimmybjj]

Sorry to revive such a old thread. In the method described by Tone God in the above quotes, would the enclosure seal itself shut?

There is alittle bit of crossover powder at the lid and case so the two parts will be fused together but its weak. You can either pry it the lid off through one of the lid holes or my favourite method is to take a driver of some sort like a nut driver, run it through one of the machined holes like a pot or switch, then give the lid a good tap from the inside. The lid will pop right out with a clean seam. I suppose if you want to be really safe you can run a knife around the gap to cut the powder but I haven't had any problems with this issue yet.

Andrew

Thanks, I'll give it a go this weekend.

[Jdansti]

Sorry for the necropost.  This thread was just referenced in another thread and my question really belongs here.

Has anyone tried the Harbor Freight powder coating system for $60?

http://www.harborfreight.com/10-30-psi-powder-coating-system-94244.html

[chromesphere]

For those wondering about coating clear over bare enclosure, here's an example of candy blue over an unsanded enclosure.  Sanding looks better.  Gives it a sort of anodized look:

Skip to 3:55

EDIT: So yeah, imperfections will show through, I still think it looks great even unsanded!  And a one layer coating job is quick as well.  Pretty sure dazatronyn (darron) does it this with on a laser etched enclosure (or laser etched afterwards).

Cant vouche for durability.  Time will tell on that one.

Paul

[Jdansti]

Good video!  Thanks!

[tranceracer]

Sorry for the necropost.  This thread was just referenced in another thread and my question really belongs here.

Has anyone tried the Harbor Freight powder coating system for $60?

http://www.harborfreight.com/10-30-psi-powder-coating-system-94244.html

I've used this.  It works.  Be sure to have the pressure set right!  I forgot to adjust it down to 25psi from 120psi and the plastic filter portion under the gun exploded!

Don't get the gun too close to the object or static electricity will jump to the enclosure or whatever you're powder coating and create small craters in the powder which are a pain to cover up w/out redoing the whole thing.

[chromesphere]

Don't get the gun too close to the object or static electricity will jump to the enclosure or whatever you're powder coating and create small craters in the powder which are a pain to cover up w/out redoing the whole thing.

Bang!  A problem that I never knew the reason for has been answered!  Thank you kind sir!
Paul

[thelonious]

Bang!  A problem that I never knew the reason for has been answered!  Thank you kind sir!

Seriously. That was gold right there. Thanks tranceracer!