NTBA

Powder coating your car parts give them a super shiny, and extremely durable finish. Powder coat is highly resistant to rock chips, and when done properly lasts much longer than most kinds of paint. Any metal part that can withstand the 400 degree curing temperature can be powder coated. Steel, cast iron, and aluminum are the most popular, and the easiest to coat. Home powder coating kits are now available so cheaply, that anyone can afford them. There are several sources for the kits. Harbor Freight has a nice one that sells (on sale) for around $59. Other sources for powder coating kits are Caswell, Eastwood, and eBay.

This is my $59 Harbor Freight powder coating kit:

The Caswell kit costs a little more, but comes with excellent customer support, and a powder coating forum where you can ask questions and learn to powder coat like a pro. You can check out the Caswell powder coating forum here. The Eastwood powder guns are a bit more expensive, and are not built as well as the Harbor Freight or Caswell guns. You can find a good deal sometimes on eBay too, but exercise normal caution when bidding.

To powder coat and get good results, you'll need:

Air compressor (the bigger the better!
Sand blaster (a blast cabinet is less messy)
Powder coating kit
Powder curing oven

AIR COMPRESSOR

The powder coating gun itself uses *very* little air, and a small compressor, or even a portable air tank will work fine. To prep your parts for powder coating, you'll need to sand blast them. That's where you need *lots* of air. If you have a small air compressor, it will work OK, you'll just spend more time waiting for it to catch up.

SAND BLASTER

You can buy a cheap sand blast kit almost anywhere. Siphon feed blasters are cheaper, and work just fine. You can buy a siphon feed sand blast kit from Menard's for as little as $10-$20. Blast cabinets are not very expensive, and make the job a *lot* less messy. I bought a Harbor Freight sand blasting cabinet for $139, but they have the same cabinet on sale sometimes for only $89. As always, be sure to follow all recommended safety procedures. Wear safety goggles, gloves, a silica approved respirator, etc. For blasting media, I recommend "Black Magnum" or equivalent. It is a slag based abrasive, and not a silica based abrasive. It is safer to use than silica.

POWDER COAT KIT

Any of the kits listed above will do a fine job. Pick your favorite, the cheapest, the easiest, or whatever makes you happy. Be careful buying a used gun. New guns with a warranty are only a few bucks more.

POWDER CURING OVEN

This is easier than it sounds. You don't need a fancy powder oven. A cast off (garbage picked?) kitchen oven will work fine. It must be an *electric* oven, and not a gas oven. Airborne powder (dust) is very flammable and can ignite easily, so a gas oven is not as safe as an electric oven. Don't use your wife's kitchen oven either, or your pizzas will never taste the same again. Pick up an old electric oven from the curb on trash day and put it out in the garage. Buy an oven thermometer at the hardware store for $6. Oven temperature dials are usually not very accurate.

POWDER

I've found the best variety and prices for powder at Caswell. Many colors are around $10 per pound. The powder is fresh, and very high quality. Eastwood probably comes in second, and Harbor Freight is last. Sometimes deals can be found on eBay, but be careful, powder has a limited shelf life.

If you've been keeping track of the costs, this is about where we're at:

Air compressor $300
Sand blast cabinet $89
Powder gun kit $59
Old electric oven $free
Oven thermometer $6
Powder $10

Starting with *nothing*, we're into this project to the tune of $464. If you already have an air compressor, we're at $164. Powder coating is pretty cheap!

Getting Started

I took some photos of my last powder coat project. They are aluminum caps for water fillers. The first step is to sand blast the parts, and get them as clean as possible.

Don't be gentle. Blast the heck out of them. The rough texture gives the powder an even better surface to adhere to.

If you are powder coating aluminum parts, you need to pre-bake or "outgas" the parts first. Aluminum is porous, and will hold oil and grease in it's pores. This can happen even on NEW parts from the oil used in the casting process. When heated, these are forced out of the aluminum and can ruin your smooth powder finish with hundreds of bubbles. Outgas the sand blasted aluminum parts at a minimum of 450 degrees for 20 minutes. When you remove them, look for signs of contaminants that may have been forced out. Sand blast again to clean the part, then apply powder and cure normally.

Once the part is clean and rough, apply the powder. The powder is electrostatically charged "positive" as it leaves the gun. There is a wire attached to the part being powder coated, giving it a "negative" charge. The powder will stick to the part with very little effort. Only 8-10psi of air pressure is used to apply the powder. You want to do this in a place where there is no wind. Often times you can hang the part from a wire to make the job easier.

The applied powder will make your part look kind of "fuzzy" and dull. Ideally the finished powder coat will have a cured thickness of 1.5mm to 2.0mm. There isn't a practical way to measure the correct powder thickness when you're applying it. It takes a little practice to get it just right. Too thin and the result will have a rough surface texture and bare spots. Too thick and the powder may not cure properly, and be brittle or chip easily. Practice on some scraps before powder coating something important.

In some ways, powder coating is very forgiving. If your first coat turned out to be too thin, or you missed some spots, you can re-apply powder right over the first coat, and cure again just like the first time. The first coat of powder will not re-cure or "re-melt", so the second coat can repair mistakes made in the first coat. If you need to strip the part and start over, you can sand blast it again (lots of work, hard to remove), or you can use a chemical stripper such as Zip Strip.

Don't worry about powder that missed the part. It is not hazardous, and can be easily swept up and thrown away. Airborne powder can be flammable, though. Do not smoke, or have any other source of combustion in the area while coating the part. Once the part is coated, the powder must be cured. This is done by heating the part to the curing temperature for a specific amount of time. Caswell powders usually cure at 400 degrees for 15-20 minutes. The curing time will vary depending on the part. To cure properly, the part itself must be kept at 400 degrees for 15-20 minutes, not just put in the oven for that long. A large part with lots of mass will take longer to cure than a small part. Stamped steel valve covers will cure faster than heavy iron brake drums, etc. Adjust your curing time accordingly.

Preheat your oven, and place the part inside. Be careful not to disturb the powder on the part. Cure at the recommended temperature for the recommended time. Turn off the oven, and cool slowly.

Any metal parts that can withstand the 400 degree curing temperature can be powder coated. Brake drums are well suited for coating. Powder coating will usually fill in fine scratches and make them smooth, but deeper gouges will need to be filled first. Bondo is a no-no. It will burn at the required 400 degree curing temperature. There is a product called "Lab Metal" that is an aluminized plastic similar to Bondo that will work for gouges that are not too deep and do not cover a large area. Some people have even used JB Weld liquid steel, but I don't have personal experience with it.

The Finished Product!

These are powder coated valve covers, valley cover, tunnel ram, carb riser, scoop butterflies, and thermostat housing. My oil pan and a number of other parts are also powder coated. Basically any part that will fit in your oven can be powder coated, although it's not a good idea to powder coat springs because the heat will ruin them.

If you have any powder coating questions that I didn't cover here, feel free to drop me an email at: cwz@mc.net or leave a message on the BBS for Hemi-T.