Page 1 of 2

A powder coating demo...

Posted: Sun Sep 14, 2008 5:45 pm
by FirstYearDeek
Hello,

The topic of powder coating has come up a few times I've noticed, so I thought I would post some pics and description for those who might be interested in having parts coated or maybe even coat some parts on your own.

First up is the part itself; This is a saddle bag (box) lid rack. They came on an interstate bag set and are chrome plated. The plating is high-quality, but neglected. (Surface rust and some pitting)

Image

The first and most important step is preparation. Since the plating is very slick, even powder coating won't stick well. Primers are usually out (the etching kind would help paint adhere, but not powder coating) because they can't handle the heat, and the powder usually sticks best to the metal surfaces.

To prep these parts, I used a stainless steel wire wheel to "rough up" the surface. Chromium plating is very hard, and you have to be aggressive. Once the "shine" is gone the part needs to be cleaned. In this photo you can see where some of the pitting became loose and caused flaking under the abrasion of the wire wheel. Not to worry; this is where powder coating shines.

Image

Prep for parts that have been plated is really the simplest. Wire wheel, light detergent, rinse, rinse, rinse. (Dry) ;) Cover anything you don't want powder coated with a high-temp plug or high-temp tape. In this case, I taped over the head of the fastener, then screwed it into the fastener hole until it touched the part. In between are the wires used to hang the part and carry the ground potential to the part. (Part of the circuit that energizes and attracts the powder) Here are the parts hanging from the oven rack.

Image

Now is the time to fill your gun with powder, attach the ground clip and get the air set right. It's also a good time to fire up the oven, getting it to flow out temps. (Whatever the max temp for the powder is. FOLLOW THE CURING SCHEDULE!) I won't go into detail about the actual coating step here; every gun/system is similar, but details are different. I'll follow up later with instructions for my gun, the Eastwood Hot Coat gun.

Coat the part evenly, staying several inches from the part. Nooks and cranies are the hardest to get to, focus some attention there. Use a well-lit area or I carry an LED flashlight with me to "shine through" the powder to see what needs more powder. These shots are after a light dusting; I tend to go completely over the part, inspect, then go completely over it again. For plated parts like this, you can't ever get the "shine" out under direct light. The powder isn't opaque until it's flowed out. (that's not technically true; but the explanation is a few paragraphs long!)

Image

After I'm satisfied with the coat, I carefully discharge the gun (trigger off, touch the exciter to the ground clip) disconnect the ground clip and carry the part to the warmed-up oven. Be careful not to bump the part. One nice thing about powder coating is that if you do mar the surface before curing, you can use a compressed air gun to just blow the powder off, then recoat.

Image

Sheesh! I need to clean that oven! Eastwood powders are good general purpose powders. They're also foolproof. As long as you follow the curing schedule (only two steps for eastwood powders) you can't go wrong.

When the parts are done, don't squelch them. Crack the oven, turn it off and let the oven and part cool together. This prevents parts with dissimilar materials from cooling too quickly and cracking the finish where the metals contract differently. (Stainless inserts are especially finicky when fastened to aluminum wheels)

So here's the finished product:

Image

The coating is chip and abrasion resistant, and forms a plastic coating of sorts that will serve as protectant and decoration for many years of service. Some high-performance coatings have Tabor ratings of 7H, which is harder than polycarbonate, and harder than all but the best epoxy paints.

Remember that chrome flaking area? The beauty of powder coatings is that they are fairly thick, compared to paint coatings. It would take a dozen or so coats of rattle-can enamel to duplicate the thickness of a single (relatively heavy) coat of powder. Because the powder builds in a layer that is self-leveling, it tends to hide minor blemishes and even large, detracting blemishes become less noticeable. For flaking like this, the sharp edges simply cannot be coated over, but check this out: powder coatings can be sanded and recoated.

So here's that spot, sanded and ready for re-coating.

Image

One coat (fairly light, in this case) and another cure cycle and this part will look just like the previous one!

The parts can be put in service immediately after cooling in most cases.

I will be following up with more detail about powders, guns, technique, etc if there is an interest shown. I'm by no means an expert, but through school, hobby coating and now my own setup at home, I've probably coated more parts than I've painted, which is quite a few.

-Deek

Posted: Sun Sep 14, 2008 9:40 pm
by mooseheadm5
Thanks! You have convinced me to go for it.

Posted: Sun Sep 14, 2008 10:32 pm
by Roady
That's great, you presented it in a manner that makes it sound easy.

Now I gotta get that compressor!

Oh boy! More toys.

I'll prolly have to get my bride a new oven so I can take hers.

BTW... I think this should be moved to the How-To Forum.

Posted: Mon Sep 15, 2008 6:43 am
by FirstYearDeek
Roady wrote:That's great, you presented it in a manner that makes it sound easy.

Now I gotta get that compressor!

Oh boy! More toys.

I'll prolly have to get my bride a new oven so I can take hers.
It is pretty easy; the ease of re-coating a part if you hose it up is to hose it off! (with air) As long as you catch a blemish before it goes in the oven, you're golden.

As far as the compressor goes, a very small one on a small (ish) receiver would work fine. Guns use something like 2 to 5 psi at a very low consumption rate. A cheapo pancake or hobby compressor would work fine, as does the "canned air" you can buy for airbrush setups.

Roady wrote:BTW... I think this should be moved to the How-To Forum.
I think you're right! [Picard voice] Make it so [/Picard voice]

-Deek

Posted: Mon Sep 15, 2008 7:15 am
by Whiskerfish
Good stuff!! Moved as requested

Posted: Mon Sep 15, 2008 10:09 am
by FirstYearDeek
Thanks, WF.

More to come... taking pictures of the actual process this evening. (putting the cover coat on that blemish you see above.)

-Deek

Posted: Mon Sep 15, 2008 10:35 am
by Roady
:lol: You do Picard very well. :lol:

And, you do the instrux very well. Thank you.

Posted: Mon Sep 15, 2008 1:03 pm
by peteybug
Great! biggrin biggrin I think I will give it a try. Can you make a dvd so my wife can watch it then she will give me the ok to buy the stuff I'll need.

Posted: Mon Sep 15, 2008 2:33 pm
by FirstYearDeek
peteybug wrote:...Can you make a dvd so my wife can watch it then she will give me the ok to buy the stuff I'll need.
:P I saw that thread on Randakks video... what a riot.

Usually when I start talking paint/powdercoat/etc. all I get from the wife is :roll:

-Deek

Posted: Mon Sep 15, 2008 10:49 pm
by peteybug
My wife loves our bikes :lol: . But a little hard to convince about new tools. But she didn't falter after watching Randakks vidio. That was all true. I even thought it was funny.

Posted: Tue Sep 16, 2008 10:57 am
by sunnbobb
Nice Demo Deek, you have me thinking about a gun. Why did you chose the Eastwood? Any particular things to look for in a gun?

RIchard

Posted: Tue Sep 16, 2008 12:43 pm
by ElPiloto
The only problem I have with powder coating is building an oven large enough for a frame. That's about the only part I would like to powder coat.

Posted: Tue Sep 16, 2008 4:12 pm
by farmertompetey
Okay, so somebody with a bike lift (like the Handy unit) in the Seattle area?

Let's get a few of the Northwest (e.g. Washington, Oregon) guys together, and put on some long-sleeve blue shirts with NGW patches, and maybe our names above the pockets. Then we'll make a video showing just how much nicer and safer it is working with a lift, and we can get all of the wives to watch it, and then, as if by magic, we'll all end up with them!!!!

Hey, it could happen...

Posted: Wed Sep 17, 2008 7:35 am
by FirstYearDeek
sunnbobb wrote:Nice Demo Deek, you have me thinking about a gun. Why did you chose the Eastwood? Any particular things to look for in a gun?

RIchard
I chose the Eastwood gun for a few reasons...

1) because it's easy to disasemble and clean. The entire gun consists of 5 parts, and requires no tools to disasembled. Only compressed air is required to clean.

2)It's got a decent voltage for the price; 15kV+ is plenty for steel and almost all alloys. There are higher voltage guns, but you start to get into $200+ for just the gun in those cases.

3)The package was on sale and came with a ton of extras; SS wire, high-temp tape and plugs, three powders of your choice, a disposable vapor trap (At the gun)

Having used the gun on a few parts now, there are a few drawbacks I've discovered.

1)The cables are just too short. I tried mounting the box to my booth wall, but ended up dragging it around with me because the parts are farther from the wall than the cables will allow. I'll probably extend them, but I haven't gotten around to it.

2)The cloud patern is not adjustable. This is not a common feature, by any means, but the simplicity of the design of the gun lends itself to this adjustability... I may experiment with some different diffusers in the future. I'll just say this gun is PERFECT for coating the inside of coil springs!

-Deek

Posted: Wed Sep 17, 2008 7:44 am
by FirstYearDeek
farmertompetey wrote:...we can get all of the wives to watch it, and then, as if by magic, we'll all end up with them!!!!

Hey, it could happen...
I love it. What a bunch of wife-whipped pocketbook-beggars we are!

-Deek