Powder Coating Tips And Information

For sure, you've heard the term "powder coating" hundreds of times, but you may still have questions about what "powder coating" really is, and when it should be used. Powder coating is an industrial coating that looks like paint but is a lot more durable. Powder coating has been used for years and you'll see it on everything from auto parts to fencing to lawn furniture to electrical fixtures. In general, anything made of metal can be powder coated.

You can buy all the equipment necessary (see the Eastwood catalog) to do your own powder coating, but it's usually a lot easier to just drop the parts off at a professional powder coater's shop and let them do the job. In simple terms, the process consists of first stripping the part of all the old paint, rust and grime so it's just clean, bare metal. Then using an electro-static process, the part is "sprayed" with the special powder in the chosen color, and then this coating is "cured" by heating the part to 400° F in an oven. What you're left with is a part that looks like it's been dipped in a vat of paint!   But, a powder coated finish is thicker than paint and much more durable. And unlike paint, it's very resistant to chemicals (gasoline, etc.) and scratching. You can sand it - and it'll scratch - but unlike paint, you won't be able to just use progressivly finer grits until the sanding marks are gone (I learned this the hard way!). It's a very hard finish and Rubbing Compounds and waxes will not alter the sheen. If you want a super-durable finish that you don't have to pamper, powder coating just might be the way to go.

You're probably wondering; "if a powder coated finish looks a lot like a painted finish, why not just paint the part and avoid all the powder coating expense and "hassle"?   Good question. Depending on what you're having coated, powder coating may or may not be the best finish choice. Here are some issues to consider:

1.   Powder coating shops are used to being ask to coat a hand-full of little brackets and fastners. But, auto paint shops may not want to mess with painting a bunch of little parts. So, if you want to go with paint, you'll probably have to do the job yourself with a spray gun or aerosol can (More Info Here).

2.   You can't powder coat parts that have been repaired with plastic or epoxy fillers (like bondo). Since the powder coater begins by stripping the part to bare metal, those bondo patches will be long gone. So, if you've been lovingly smoothing out your dented bus bumper with bondo and lots of sanding, forget about having it powder coated - you're stuck with painting it.

3.   Color limitations. Most powder coaters offer a rainbow of color choices, including metallics, and they offer various sheens from flat to super glossy. For most applications, the powder coater will have a shade of powder that is close to what you're looking for. But, they usually won't "mix" special colors like an Auto Paint shop will. So if you want your bus wheels to be painted exactly "L82 Silver White", the powder coater's "standard white" powder probably won't do, so you're better off with the painter.

4.   Results vary by shop, but in general, a powder-coated finish will have a slight "orange peel" texture. It's not excessive, but it's there and it'll be more apparent if you've chosen a "glossy" sheen instead of a semi-gloss or flat sheen. Obviously a newly painted surface will also have an "orange peel" texture but with a painted finish you can color-sand it to get a mirror-smooth finish. You can't color-sand a powder coated finish, so what you see is what you get (although we've read about restorers sanding a powder coated finish to flatten the texture and then shooting it with a couple coats of clear to bring back the gloss, but now it's a painted surface, so this sounds more like a desperate "fix", than a "planned procedure"). On the intake manifold or even on wheels, this texture will usually be no big deal, but on large flat surfaces (like the engine's fan shroud), this orange peel texture will be more obvious. Most people don't stress about this, so just discuss it with your powder coater and check out samples of his work so you know exactly what to expect in the final finish.

5.   Don't have "pot metal" parts powder coated. Some powder coaters may say; "yeah, they'll come out fine" but we've seen the coat hooks from an early bus come back from the powder coater's with a pitted and bubbled finish that had to be tediously removed by hand so they could be painted instead.

6.   Having the intake manifold powder coated is a really good idea. First, when the shop dips the manifold to strip it, all the caked-up junk in the heat-riser tubing will come out (so you can skip the frustrating hand-reaming). Second, most shops will have a good selection of medium gray colors that will look very "correct" with the black engine tin. Lastly, although the intake manifold doesn't get as hot as the exhaust manifold, why risk having a painted intake manifold discolor from engine heat (especially where the flanges bolt to the heads).

7.   The belly pan (aka "skid pan") under the front of your bus is a another great candidate for powder coating. Go with the gloss black to match the front suspension. Wheels and bus bumpers (if yours aren't riddled with bondo) and the front emblem are also good powder coating candidates - have them all done the same color of white as close to "L82 Silver White" as you can get. The brake, clutch and accelerator pedals are also good candidates - probably go with a semi-gloss black here.

8.   It's probably not a great idea to have your gas tank powder coated. Often, the seams, filler neck or pin-hole repairs have been soldered, which will quickly melt away during the extreme heat of the powder coating process. Why take a chance - just have it painted.

9.   Don't have the "squirrel cage" fan (inside the engine shroud) powder coated. This fan is precisely balanced at the factory, and a slightly uneven powder coat can get it out-of-balance. Nobody will see the fan anyway, so just clean it well, paint it with an aerosol can and forget about it.

10.   If you have the crank pulley powder coated, make sure the shop knows that they must coat only the pulley and not the hub on the back (the red area in the picture here) or the inside hole (the green area in the picture) that press-fits onto the end of the crank. This fit is tight enough with bare metal to metal! The powder coater can easily mask off these areas, but it might be safer just to paint the pulley yourself with an aerosol can, if you worry that he might ignore your request.

11.   You may not want to have your seat springs powder coated. Since this is a thick coating, it will actually "bridge" any parts of the springs or frame that that are touching each other. The first time you sit down on your newly restored seat, all the springs will flex and move, breaking these "coated" joints. I guess you could take the seat assembly and springs apart and have the frame powder coated without the springs, but it seems like it's a whole lot easier just to have the complete seat spring assembly stripped and painted without taking it apart.

12.   Before dropping off your parts at the coaters, make sure you've stripped them down to their most basic form. For example; if you're having your bug's frame/pans powder coated, remove everything that can be unbolted and especially remove non-metal parts like bushings or grommets and metal parts you don't want coated (like fuel and brake lines). If you're having your engine tin powder coated, remove the insulation packing (watch out, this is asbestos!!!) under the semi-circular pieces that cover the mounting flanges on both ends of the heat riser.

13.   Make sure your powder coater plugs all the threaded holes and masks all the studs. The coating is a thick, hard finish, and if it's allowed to overspray down inside the threaded holes on your engine tin (for example), later you won't be able to tread the screws into the holes. And unlike paint, you can't just chase the threads clean with a little lacquer thinner (you can chase the threads but it's a pain in the ...).

14.   Check your parts for dents before taking them to the powder coater. Covered with grease, rust and paint the dents may be difficult to see. But a nice glossy powder coating will really highlight all the flaws (just like a new coat of paint would) and there's nothing worse than getting a fresh part back from the powder coater and noticing for the first time that it's wavy and dented. You might consider stripping the part (or paying someone to strip it) so you can see the dents and pound them out before you head to the powder coater. You might also consider welding up and grinding down any extra holes or tears. If you see a small dent in your part, after it comes back from the powder coater's, you can try to gently pound it out using rag-covered dollies and a rag-covered hammer, cuz if your dent straightening really messes up the coating, you're just out the cost of having it coated again! Curiously, even though powder coating is a very hard finish, bent or wavy powder coated tin can usually be gently bent back into shape without cracking the finish. But the point here is that both paint and powder coating will usually highlight surface imperfections, so straighten things out, before having it coated.

15.   Regardless of whether you've decided to have the parts powder coated or painted, take a minute to see what else you'll want coated the same color. It's always cheaper to have all the parts coated at the same time instead of dropping off the stragglers at a later time.

16.   When you drop your parts off, make a detailed list of what you're having coated (maybe even shoot a couple of digital pics of everything layed out on the coater's shop floor) so there won't be any confusion when you return to pick up the freshly coated parts. Most shops are very careful and professional, but sometimes things get hectic and small parts get misplaced, and having a little documentation will help insure that you get all of your parts back. In addition, taking a few minutes to inventory your parts with the coater, let's him know you're on your game, and he'll be more likely to be extra careful with your stuff.

17.   Most powder coating shops will coat just about anything metallic, from nuts, bolts and washers to an entire car chassis. They are only limited by what will fit in their "curing" oven! Ask other gearheads in your area and at car shows, for a recommendation of a reliable coater. Most cad and chrome platers also do powder coating, even though the powder coating process is not at all like the traditional "plating" processes.
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