powder coating

[bmwtodd1]

Powder coating is an electrical process in which a positive side (part) and negative side (ground) (I may have backwards, but process is the same) have a completed circuit, with the powder itself being charged and completing a circuit. Much like iron is attracted to a magnet.
What occurs is that the part is heated to around 400 degrees or so, depending on the density of the part, the powder is electrically attracted to the part, it adheres and melts, or flows out somewhat. As the powder is applied, it creates thickness.

Powder does not work like primer however, it will form the voids of the part to which it is applied. There are methods of using filler, but these are cumbersome, and if the topcoat is a light color, the filler will likely show through.

I read a members post about having a suspension powder coated, and he was quoted $500.00 for the powder coating, plus blasting.
I use the same method of quoting, but will never use a firm quote.

Powder coating itself is relatively inexpensive. The costs rise due to increase in batches of coating, size/weight of the material. Thicker materials take more powder, and take longer to bake. From a powder coaters perspective, the actual cost of powdercoating his suspension, would cost the provider roughly $50.00 in material and electricity. I know this, because I am powdercoating my own EM suspension.
The real cost is in the prep: The following steps are time consuming and if you are willing to do the work, you can drastically lower your project cost:
Bead blast, or sandblast your part. Then go over it with a brown scotch brite pad. (about 250 grit, if I had to guess)
Everything needs to be removed. No rust, all paint, primer.

Keep in mind that rubber, bearings, seals, etc cannot be on the part when powder coated. They leak grease when warm and ruin the powder, not to mention their ability to melt.

If possible provide CLEAN sacrificial bolts to fill threaded holes. Rethreading threads that have been powdercoated is a painful process.

Taping costs money. Masking parts doesn’t happen with normal masking tape, a special high temperature silicone tape is used. You can buy it from eastwood or other vendors. A roll is around $15.00. The labor to tape off the parts is time consuming, so ask your provider if you can do it yourself.
Before any taping is done, or powdercoating is done the part needs to be cleaned, preferably with hot/soapy water, scrubbed, (especially important dust imbeds itself to metal and rinsing alone doesn’t remove it) and lastly cleaned with lacquer thinner.
Your provider will most likely do the last step for you, but doing it yourself is good insurance.

So to sum this all up, before you seek a quote from a powder coating place, thoroughly inform them of what you intend to do, or not do. It will make a big difference on your quote.

Hope this helps…Todd

[jdflight]

Todd

Thank you for the information, it is differently helpful in understanding the cost. With this information I am almost hesitant to go with the cheaper quote, since they might be cutting corners to keep the cost down.

[bmwtodd1]

You are welcome. Not a very technical writeup, but it gets the point across.

[jdflight]

bmwtodd1

When you have done drums in the past did you have them turned after the powder coating process? I just got mine back and it appears they cleaned the brake lining surface and trying to decide if I need to turn them before installing them

[notched]

People have differing opinions on the use of powder coat. The pros to it is it goes on smooth and there is typically less prep (clean, degrease, remove rust, etc) as opposed to paint. But the issue I have found with powder coating is if you scratch the coating it becomes darn near impossible to touch it up easily and it tends to delaminate and peel when this happens. I have also found that sharp edges on items such as control arms and such can become another point for delamination.
Over the years I have used power coating in different places. Some spots hold up well and others degrade.
On my recent projects I have been using epoxy primer and epoxy or urethane based paints with great success. But again, that is my own experience.
Here in New Jersey I live in a very damp/humid climate. It does not take long for things to rust if not properly coated. So with paint, having the multiple layers (primer and paint) seems to work better for me.

[thewolfe]

Powder coat needs the same prep and squeaky clean surface that paint does if you want good adhesion that lasts. You can't powder coat over grease and rust and expect a good finish. The shop I take my parts to media blasts then does a degreaser immersion, then a phosphate immersion for steel parts which etches and adds corrosion resistance. Final step is the powder. Not all shops do degrease and phosphate immersions so I can see different people possibly having different experiences with the final results. I have had many parts powder coated and never had any delaminate on me.

[notched]

Powder coat needs the same prep and squeaky clean surface that paint does if you want good adhesion that lasts. You can't powder coat over grease and rust and expect a good finish. The shop I take my parts to media blasts then does a degreaser immersion, then a phosphate immersion for steel parts which etches and adds corrosion resistance. Final step is the powder. Not all shops do degrease and phosphate immersions so I can see different people possibly having different experiences with the final results. I have had many parts powder coated and never had any delaminate on me.

How do you touch it up when you scratch it?

[thewolfe]

You can't touch up scratched powder coat. Didn't you already mention that?

[notched]

Yes. I thought that you alluded that there was a way to.
My original post was not put it down. But I did all of the things as far as prep work when coating the items myself including soaking items in phosphoric acid). I have been doing that on a lot of things for years. I had some of the stuff coated by a place that used to coat for Orange County Choppers. I still had problems as I described above where the powder splits on sharp edges...........this has happened on control arms front and rear for my Grand National.
I have shown it to different people and everyone has excuses as to why it happened. I never would coat or paint over something oily, greasy, rusty or old finish. My bottom line was I don't have to jump through as many hoops to get a finish with paint that will last.

[bmwtodd1]

Yes there are definitely pros and cons for using powdercoat. I like it for it's economics, it is cheaper to do, unless we are talking big pieces then the electricity is a little more. To answer JDflights question, I normally tape off surfaces that you don't want powdercoat on. Powdercoat can be sanded off, but that takes a long time. I've never had anything chip, not that it couldn't happen, but I do a lot of motorcycle parts and have good luck. I could see where a footpeg might be an issue though. And lastly, touch up can occur, by feathering out the chip, and re-powdercoating, but the downside is that the thickness would increase, and not to mention the hassle of taking it off, and back in to the provider. Paint is compatible, so chips could be touched up with paint.
It's all personal preference.

[lostboy]

You can't touch up scratched powder coat. Didn't you already mention that?

Not necessarily true. I get my powders from prismatic and they will make paint versions of any powder they carry. At the end of the day, it's just like paint, you'll always have the "touch up" spot until you blast (or strip) it all and recoat. I know a guy who did a whole vw floor pan in gloss black powder here in NJ.


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[Corsa bill]

Ok, I've studied You Tube videos, where people use ovens to power coating. Of course not the one in the kitchen. They even show people doing oven extentions on the ovens. Has anyone done this?

[bmwtodd1]

I have two methods that I use. I built a steel box (with handle) that sits on top of the oven door, when it is in the down position. It works just fine, and it doesn't lose as much heat as one would think. You will want to use welding gloves to pick it up though. It doesn't get so hot like a stove top element. You will need to work fast though, and having someone help you is a plus. After pre-baking the part, person 2 lifts the lid, you grab the part and go to where you will coat it. They lift the lid when you come back. Allow an extra 10 minutes of bake time since it has to warm up more than if the door was just opened and closed.

My buddy and I built a real nice one too 4'x4'x6' just right for hanging motorcycle frames in and larger pieces. I'm on the road right now, but can post pictures when I get home. It's cost was about $500 or so, and is handy.

Those UV lights that Eastwood sells for powdercoating are junk. I went down that road, and you have this big damn thing to trip around all the time.

You were right on the sharp edges, I try to smooth them, wherever possible. But it isn't always completely possible. You have to increase the layer of powder there just a little to give it more buildup.

I have done touch up, powdercoating wise, the part has to be scuffed, and wiped clean with a grease remover, and coated again. I do like the paint method much better.

I started doing it just because my motorcycle hobby had so many parts that could be coated, and I found out that it was economical to do, much more than spray paint. It kind of morphed from there and became a frequent task for customers around the shop. I normally don't charge much, and if the customer wants to sit and blast his own part, that's even better.

[lostboy]

I have two methods that I use. I built a steel box (with handle) that sits on top of the oven door, when it is in the down position. It works just fine, and it doesn't lose as much heat as one would think. You will want to use welding gloves to pick it up though. It doesn't get so hot like a stove top element. You will need to work fast though, and having someone help you is a plus. After pre-baking the part, person 2 lifts the lid, you grab the part and go to where you will coat it. They lift the lid when you come back. Allow an extra 10 minutes of bake time since it has to warm up more than if the door was just opened and closed.

My buddy and I built a real nice one too 4'x4'x6' just right for hanging motorcycle frames in and larger pieces. I'm on the road right now, but can post pictures when I get home. It's cost was about $500 or so, and is handy.

Those UV lights that Eastwood sells for powdercoating are junk. I went down that road, and you have this big damn thing to trip around all the time.

You were right on the sharp edges, I try to smooth them, wherever possible. But it isn't always completely possible. You have to increase the layer of powder there just a little to give it more buildup.

I have done touch up, powdercoating wise, the part has to be scuffed, and wiped clean with a grease remover, and coated again. I do like the paint method much better.

I started doing it just because my motorcycle hobby had so many parts that could be coated, and I found out that it was economical to do, much more than spray paint. It kind of morphed from there and became a frequent task for customers around the shop. I normally don't charge much, and if the customer wants to sit and blast his own part, that's even better.

I use an old rotisserie chicken oven. On full blast is is just slightly over 400 degrees which is curing temp. If it's a big part I converted an old smoker into an oven. I still send my big stuff out, but like bmwtodd said, my motorcycle hobby has so many little parts that I can't justify waiting for or dropping off to someone to do. For instance, I would have never powdercoated my wheel cylinders or backing plates, but since I can, I did.


Btw the chicken oven is perfect size imo and it has a timer.... I could easily do a Tacoma drum (one at a time) on the rack, or multiple things hanging from the hooks I made.

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[Nicad]

I enjoy powder coating parts and am usually pretty good about the prep of them. WHen put into a harsh Canadian winter (Salt all over the roads) I find that the powder coated items I have made have not held up nearly as well as a POR 15 coated part with a top coat. I have seen on youtube a guy who made an oven for long parts by grafting an insulated stove pipe onto a hot plate.

[lostboy]

My George foreman chicken oven...


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