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)
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.
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.
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!)
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.
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:
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.
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.
"Eat, drink and be merry. For tomorrow we die."
1975 GL 1000 (First Year) under the knife; soon to be a cafe' inspired "Boss" of a freedom machine.