Powder Coating Tutorial and Discussion

[PerroGrande]

I'd like to first thank everyone who sent me kind words about the powder coating samples I posted in the PICTURES thread.  Enough people seemed interested in the process that I thought it would be cool to start a thread to discuss this process.

I had the opportunity today to photograph the majority of my gear and the process I've developed.  There is no time like the present, so here we go with the tutorial thread.

DISCLAIMERS!!!

1) I'm not an employee or a shill for Eastwoodco.com or PowderBuyThePound.com.  I'm using their stuff in my examples because that is what I happen to have.
2) I'm not an expert nor highly experienced powder coater.  I'm still learning.  However, I've made a lot of progress and can generally produce acceptable results.
3) I don't have pro gear, and a lot of the stuff I use is rigged together.  I'm doing all this on a budget. 
4) If you have suggestions/improvements/etc., please POST THEM and share the knowledge.
5) I'm not trying to steal business from PPP, Small Bear, or any other powder coater out there.  For the majority of folks, buying a powder coated enclosure may be the best alternative.  I got into this because I love learning new things and like to be a self-sufficient as possible...
6) Powder Coating is vastly superior environmentally to paint, from all the research I've done.  However, that doesn't mean that you shouldn't exercise appropriate caution when doing this...

Okay!!!

Let's start with the gear that I'm using...

[PerroGrande]

I started by purchasing a kit from www.eastwoodco.com. 

You can see it here:  http://www.eastwoodco.com/shopping/product/detailmain.jsp?itemID=5572&itemType=PRODUCT&iMainCat=459&iSubCat=460&iProductID=5572

They have other kits, both lower and higher in price.  I wanted to get all the major components along with a few colors right from the beginning.

So...   You're going to need:

An Air Compressor...  I hate this thing, but it was a gift.  It is smaller than I'd like, and is really freaking loud...



The Powder Coating Gun...


Powder (This is how it came in the kit from Eastwood)...


Or... if you like the products at Powderbuythepound.com, it comes like this:


Which is why it is nice to have some spare bottles for your gun...

[PerroGrande]

You may need some plugs so that powder doesn't get into the threads of your boxes.  These are high-temperature plugs from the Eastwood kit.


High temperature tape to mask areas you don't want covered (I've not used this yet)...


Wire for grounding and/or hanging parts...


You'll want some basic personal protection stuff...


...And an oven big enough to hold what you're coating.  NEVER use it for food after using it for powder coating!!!  This one will hold the top and bottom to a 1590NS from PPP without problem. 

[PerroGrande]

Lastly, in the equipment category, you'll need some odds and ends to make your life a little easier...

Some sort of spraying attachment for your compressor (used in the various clean-up operations):


Some household items...  I rarely use the spatula, but the spoon is handy for transferring powder to bottles.  The little metal thing will come in handy later on...


Pipe cleaners (used in the clean-up stage)


A multi-function cloth-like object (okay, it is an old sock... useful as an oven mitt/glove/etc)


Some 220-grit wet/dry sandpaper:




And, if necessary, some patience and/or fortitude... 

[PerroGrande]

To actually powder coat, I've rigged up a "booth" using some cardboard and newspapers.  It is tremendously ugly, but was free and actually works quite well...





Notice that along the top, I've installed a wooden dowel from which several pieces of wire shaped into hooks descend.  These hooks are used to support the parts as well as to ground them during the painting process.   Here is a closer look:

[PerroGrande]

Now -- on to the process itself.

MOST IMPORTANT!!! Water, dirt, and grease are your mortal enemy when powder coating.  A lot of the steps I take are specifically designed to combat this foe...

I start with a fairly well-sanded enclosure.  This unit is a 1590NS from PedalPartsPlus.com.  I wet-sanded it to this level of shine with 180-grit wet-dry sandpaper. 



After I'm done with the initial sanding process, I bake it in my oven at 300 degrees for *at least* 20 minutes...  Longer is better.  For this example, I actually ended up baking it for about 45 minutes, which is fine...



After it has had a chance to cool (although not completely), I remove it from the oven being careful not to touch the enclosure.  In fact, from this point on, it will not be touched by human hands until the entire process is complete.


No touching!!



From here, I DRY SAND the enclosure with 220-grit wet-dry sandpaper (the paper must be dry, too -- in fact, I use sandpaper that has never been wet.).  Again, I DO NOT TOUCH the enclosure.



The dust/dirt/grit that this second sanding produces is shown here (lower left).  It will be a fine, dark powder typically.


I regularly blow away this dirt AND clean the sandpaper using compressed air at about 30PSI...   Make sure your compressor has a moisture trap or doesn't allow water into the air!



Once the second sanding is done, the enclosure looks like this:


And back into the oven for another baking -- this time at 170 degrees for at least 30 minutes.  Longer is okay.  The idea is to drive out any remaining water, and to have the enclosure warm for the actual powder coating process...

[PerroGrande]

Now for the fun part!!! 

While the oven is baking the enclosure for the second time, I get everything set up for the actual powder coating!  For starters, I set my compressor to ~6-7 PSI.  My gun specifies 5-10 PSI, and experience has shown that the lower-side of this scale works better...



The gun gets connected to the air hose, and I ground my hook contraption to the red (ground) lead of the gun's controller.  Yes, it is a ground and it is a red clip -- go figure!  For the actual coating process, this red lead and the connection to my hook assembly are outside the "booth".



Recently, I've been including a "powder catcher" in my booth.  This is nothing more than a couple sheets of aluminum foil that I ground.  The idea is that this will catch some of the charged powder that doesn't end up on my enclosure.  It seems to work very well, so I'm going to keep doing it.  It also makes for a less messy clean-up.



Just before I remove the enclosure from the oven, I attach the paint bottle to the gun.



I then remove the enclosure from the oven (which has been baking it at around 170 degrees for a while now), again avoiding any touching.  I just carry it on the oven rack over to the hook contraption...



And on to the hook it goes without ever being touched.  In this case, I have it hooked through the hole for the power adapter.  I could easily hook it via a screw hole, or other method.  I usually "rehearse" this with a given enclosure well before the process starts so I know how I'm going to hang it.



After I've got the part on the hook, I crank up the oven to the powder's specified "flow" temperature.  In this case, the powder wants to flow out at 450 degrees for 3-5 minutes, then cure at 400 degrees for 20 minutes.  I like to have the oven at temperature when I transfer the enclosures after they are coated, so I use this opportunity to preheat.



I give the gun a little squirt without the trigger (charging voltage) just to make sure I have good flow, proper pressure, etc.  The powder won't stick to much of anything since I didn't have the charging trigger pressed.


Then on with the coating...  The pictures make it seem like the gun is closer to the part than it really is.  I'm probably about 6-8 inches from the part throughout the process.  The button is depressed the entire time, so the powder exits the gun with a positive charge.



I took this shot while the powder was actually being blown by the gun.  The picture looks very messy and chaotic, but the process is actually fairly well controlled.



The bottom panel won't get a very good coat, so I use my metal "gizmo" to gently tilt up the box long enough to get a coat of powder on it.  Here it is just prior to being coated:



Here is the coated box ready to be transferred from the hanger.


I carefully transfer it back to the oven rack...


And into the oven it goes for flow-out.  The PART (not the oven) needs to reach and maintain the flow-out temperature for the amount of time specified for the particular powder in use (many of them are different, so read the instructions/specs for the powder you are using).


After the flow-out period is done, I reduce the oven temperature to the appropriate "cure" temperature, and set the timer for the time specified by the powder spec.  When the timer is done, I simply allow the part to cool in the oven.  RESIST THE TEMPTATION to remove the part right away. Not only is it freaking hot and will burn you, but it may still be a little sticky, and dust/bugs/etc may stick to it.  To avoid this, I just allow it to cool gradually in the oven...

[PerroGrande]

After the part has cooled in the oven, it can be removed and put into service right away. 

Here is the result of this powder coating escapade:






Not too shabby! 

This enclosure is drilled for 2 potentiometers and two SPST switches, along with the normal power, input, output, stomp, and LED, of course.  It is destined to hold a RunOffGroove.com THOR when the internals are added.

[Ice-9]

fantastic tutorial and thanks for this. I remember doing powder coating at school a lot of years ago (erm 1980's) and it was a totally diferent method. how it was done back then, possibly also a different thing altogether as well, was like this.

The metal to be coated was heated up to a hight temp over a flame, (at school it was a coal furnace, at home i just heated up over the cooker gas hob, lol) then the item to be coated was just dipped into the plastic coating dust and removed after a couple of seconds, at 15 years old i remember being really impressed with the results.

I will definately be checking out any equipment available over here in the UK as after reading your tut, i'm so impressed.

[jimbob]

Thanks for the tutorial!!!!!!!!!  I been thinking about buying a set but now I doubt I will. Although it looks amazing- it also looks like quite an investment of both time and money for just a hobby-  atleast in my case it might be better to just buy pre done or paint with simigloss enamel. Also it would be quite a while before I made that money back up.

But I do really appreciate your time and effort for this!!

[Cardboard Tube Samurai]

Very impressive, well done. I really need to find somewhere in Oz to get me one of those kits

[tiges_ tendres]

John,

Thank you so much for taking the time to do this!  I am hoping that this will be a great spark for me because I hate spray painting!

Again, and to anyone who has written up a tutorial, Thank you!

[John Lyons]

Thanks for writing this all up and for the pics and tips!
It takes a long time get this stuff together...I know...
The boxes look very nice.

john

[PerroGrande]

Thanks for the encouraging words! 

I actually had a lot of fun putting the tutorial together.  I needed to coat that box anyway, and due to a series of events that happened, I ended up with the free time to do it.  I've gotten a lot of good advice and information from this forum, so it is my distinct pleasure to give back in some small way.

I'll keep feeding this thread as I keep experimenting and learning.  I'm still keeping things fairly basic -- I haven't gotten into clear coats or fancy designs yet.  Clear coating with powder is next.   

[Apehouse]

Very, very cool of you! I've always wondered about these kits and the details.
And super fast of you as well.
thanks a ton!
-Greg

[asfastasdark]

So... what exactly is powder coating? Is it charging the powder positively, and because the box is grounded it attracts the powder? I have to say that the results are extremely good! I'm impressed! Though I probably won't be buying a kit considering the price (I think my dad has one of these air compressors in the garage), I really do have to say: I learned something new today! 

[PerroGrande]

Powder coating guns positively charge the powder particles as they pass through the gun.  The target part to be painted is grounded, so the positively charged paint is attracted.  When the target part (enclosure in this case) is warm, it helps the paint powder *stay* on the target.

As for the powders themselves, there are four major varieties:

Epoxy
Hybrid Epoxy-Polyester
Polyester (TGIC)
Urethane Polyester ("Urethane")

Each one has certain characteristics and strengths.  All of the powders I've been using are the Polyester (TGIC) variety.

[fixr1984]

Could you sand a box "mirror" smooth and then clear powercoat it?
Would it still stick if it wasn't a little bit rough?

[Filament]

Great tutorial, thanks.  I may just have to get into this myself.  I'm fortunate to have a wife that is very supportive of my habit. 

Is it just me or does the enclosure look like it's had the Foxx Tone Machine treatment after it's been sprayed but before it's been baked?


Thanks again!

[PerroGrande]

Could you sand a box "mirror" smooth and then clear powercoat it?
Would it still stick if it wasn't a little bit rough?

I haven't tried any of the clear powder yet, but this is a question I'm very interested in as well.  I've done several pedals for people that were high-polish aluminum (nearly to mirror level).  It would be nice to have a clear coat that is tougher and better than the traditional clears.