WHAT IS POWDER COATING
In last few years, Powder Coating of automotive parts and accessories has become very popular with enthusiasts. This popularity with powder coated products has encouraged many aftermarket manufactures to offer their products dressed in these new finishes. Everything from alternators to engine brackets are available in a wide range of powder colors. Even some re-production parts are now being offered in powder coated finishes.
Ok, what happens if your part is not on the list of new powder coated products? In the past, this meant you would need to have them finished by a professional coatings shop. For small parts, this is simply not cost effective. Short of having a chassis or other parts of the same scale coated, small parts coating was definitely in the realm of the customizers. The good news is there is now an affordable powder coating system for the home shop.
The new HotCoat powder coating system now provides the average hobbyist with an easy to use powder-coating system for the home shop. Available through the Eastwood Company, the HotCoat system provides a high quality, tough polyester finish at a very low cost.
WHY POWDER COATING
You may be asking your self "why powder coat"? Powder coating is the best protection you can apply to part for corrosion and chip protection. The polyester finish is very tough and durable (10 times more durable than spray-on paint). Powder coated finishes are resistant to chemicals such as fuels and brake fluids. Coated parts are heat resistant to 350 degrees and will not fade or deteriorate under UV light. When properly applied, these finishes are flexible enough to dent without chipping.
The cost of powder coating parts with the HotCoat system is comparable to that of spray painting with much better results. The real saving are in the clean up, you will not have to use any solvents or deal with any messy over-spray. The HotCoat system is environmentally friendly. Since powder coating does not rely on solvents, it helps reduce emissions of VOC's (Volatile Organic Compounds) that result from the use of solvent propelled liquid paints.
READY TO COAT
Not yet! To get the best results with any finish, it is important to understand the characteristics of the product and it’s proper application. As a general rule, preparations for powder coating are pretty much the same as for solvent propelled liquid paints, but there are a few exceptions. Before we get into that, lets have a look at the characteristics of powder finish itself.
The HotCoat system uses a Polyester based, thermosetting compound that is electrostatically applied. In the electrostatic application, a powder comprised of finely ground particles of pigment and resins are electrostatically charged as they are sprayed onto a metal or alloy component. The component being coated is negatively grounded so that when the positive charged powder, emitted from the power gun, will adhere to the component. Once coated, the component is moved into a 400 degree curing oven where a chemical transition occurs, resulting in a uniform, durable, high quality finish.
WHAT CAN BE COATED
As you may have already surmised, components to be powder coated by the electrostatic process must be of a conductive metal or alloy. Also, these components must be able to withstand the 400-degree curing process. There are not too many automotive parts that fall outside of these parameters, but it something to keep in mind. While exhaust "headers" come to mind as exceeding this temperature, as well as most of the rest of the exhaust system, it is hard to think of any other components that operate at temperatures above 400 degrees. We’ll leave common sense to be your guild as to what can and cannot be powder coated.
TESTING THE HOTCOAT SYSTEM
Recently, we test drove the HotCoat system available through the Eastwood Company. We choose the Deluxe Kit because it offered the best value for our needs. Priced under $200, this kit provides the hobbyist with everything he or she will ever need to turn-out top quality finishes. Other kits are available and start at about $150.
When the kit arrived, We were interested to see just how long it would take to read the instructions, setup a work area, coat something and cure it. In just 2 short hours we had our answer, as well as our first finished product. Subsequent projects, excluding prep time, have taken an about an hour to complete. While this may sound longer than simply squirting on some spray paint, it isn’t. When the part is cool, it's ready to slap on. You no longer have to wait through long drying times or for good weather to protect and finish your parts.
UNPACKING THE KIT
Our Deluxe kit included the powder gun, cup, power source and activator switch, 2 disposable in-line filter, high temperature masking tape, silicon plugs, stainless steel wire, 3 extra cups and 2 cans of a standard color powder. We also ordered a few more colors to help get us started.
Eastwood offers OEM engine colors for both Ford and GM products. If you have another make, there are many other colors that are very close to some of the other manufactures OEM engine colors.
If your into a custom look, there are also some exotic colors or "Specialty" colors that can be applied over chrome or clean steel to achieve that "Custom" look. In short, there are over 45 different colors available to choose from. Always use original HotCoat powders with the HotCoat system to assure yourself your of getting only the best in quality and protection.
This kit also includes silicon plugs. During curing, these plugs prevent powders from flowing into areas where you do not want powder to flow. Along the same lines, the Fiberglass Tape supplied in the kit helps you mask off those areas where you do not want powder. Both are designed to handle the 400 degree curing temperature. The silicon plugs can also be used as "feet" to set parts on during curing in the oven. The Stainless Steel wire works well for hanging parts during coating and curing.
Dry air is very important in powder coating, so Air Filters are supply to assure you have just that. The Starter and Deluxe kits provide 3 Extra Cups for fast switching between colors.
Last but not least, there is an instruction manual. The instructions are very good and cover most everything you need to know to get started.
The following is a brief overview of the project and does not cover all the information you need to know about safety and the proper use of the equipment. The entire instruction manual is online. Please read and follow the instructions and follow them. Doing so will guarantee you great results without any surprises. Now onward!
In anticipation of the arrival of the powder coating kit, we searched the local swap meets for a bargain that would lend itself to this project. We didn't have look long before we ran across this GM alternator for a mere $5.
Constructed of cast aluminum, the alternator case does require some prep to achieve professional results. This is due the rough cast surface of the aluminum case. We began by tearing down the alternator and removing all the components from the case. This included both front and rear bearings.
Once the case had been stripped, we bead blasted the case to remove any paint or dirt on the surface. Also, it is important to remove any aluminum oxide from the case to assure good bonding of the powder. This is a process that should undertaken with all metals. If you do not have a blasting cabinet, you should consider purchasing one. You can pick up inexpensive bench top models for this type of work. If blasting is not an option, you can remove these contaminates with a soft wire brush and chemical cleaners, but we recommend media blasting for the best results.
As we noted earlier, there is some prep needed to make the case surface smoother. Using Eastwood's Expander Wheel (right) with a 220 grit band, we smoothed down the rough casting. After roughing the casting down with the 220 grit band, we dropped down to a 320 grit band and then to a 3M Scotchbrite "Fine" band.
wpe82.jpg (18279 bytes)After smoothing off the case, we drop it back into the blasting cabinet for a "light" dusting of glass beads on a low pressure setting. This finial step in the case finishing is necessary to blend away sanding scratches and provide a good tooth for the powder coating material.
Next, we prep baked the case at 400 degrees for 10 minutes. This process drives out any oils trapped in the pours of the casting. Once the case was cool, it was wiped down with a wax and grease remover. We used PRE Painting Prep (#1679Z) from the Eastwood Company and blew the part dry with clean air. One note here, air from an air compressor is not always clean. In some cases there maybe oil and moisture carry over. Depending on your setup, you may need a filter trap to make sure your not blowing oil laden air all over your clean parts.
Also, latex gloves should be worn from now on to protect yourself, as well as the part from contaminates. Oils from your fingers will cause you that same problems in powder coating as they do when spray painting. Clean, Clean, Clean, we can't say it enough! The preparation is the most important step in any finishing work and powder coating is no exception. Also, use paper towels or a lint free cloth to wipe down your parts.
Here you can see our setup for powder coating. It is very simple, just two shop towels on a work bench. There is very little mess associated with this process. we're sure that larger parts might require a couple more towels, but that is really all there is to setting up a work area. We also tried a linen sheet, that worked well too.
From the photo you can see the ground lead attached to our part and the powder coating gun full of "Chassis Black" powder. As mentioned earlier, this lead sets up a grounded surface for the charged powder to cling to. In this case the grounded surface is the alternator case.
The gun requires .5 or more cfm at 5-10 psi, with 8 psi being ideal. Do not exceed 10 psi! On our setup, 5 psi was ideal and produced a fine fog of powder. We work out the pressure on some sheet metal blanks to verify the coverage. Look for a setting that lays down enough powder to cover the part in a even dusting. Too much air dumps powder rather than dusting the part in several passes. The goal is to adjust the volume to allow you about 8" between the gun and part being coated while putting down a light coat on each pass.
The powder gun emits a fog of powder in fashion unlike a cup spray gun. You will have to turn the gun parallel to your work at times to get the coverage required. You should build the powder layer to between 1 and 2 mils in thickness. Any thicker than 3 mils could result in flow problems and any less might leave you with thin edges. If you over-coat or disturb the powder in a negative way, simply take the part outside and blow it clean of powder. You can then start fresh...you can't do that with spray paint. Of course, you will need to wear a dust mask and latex gloves to protect yourself during the handling and application of power.
We picked up a used electric oven for the shop at a local used appliance store for $35. While it was not much to look at, it was in good working order and provided us with a safe way to cure our parts. HotCoat recommends an electric oven over that of a gas oven due to the flammability of the powder if it were to come into direct contact with an open flame. Also, for obvious reasons, you should not use an oven that food is prepared in for curing parts. Good ventilation is required to prevent breathing of any toxic fumes that may be present during curing.
Once the powder as been applied, we slipped the case onto a piece of sheetmetal for transport to the oven.
Next, we heated the oven to 400 °F for 20-30 minutes. Once the oven was ready, we place the part in the oven and allowed it to bake until we could see an even "glossing" or "flow" of the powder material. Once the powder has reached this "flow" point, cure for 15 to 20 minutes. This allows for complete flow-out and curing of the powder. Larger parts make take a little longer to reach a flow point, but the curing time is the same 15 to 20 minutes. Use the shorter time as a minimum, but if you see you need more time to get a good flow-out of the powder, add an additional 5 minutes to the curing time.
Keep the door closed and view your work through the oven window. Opening and closing the door too much will delay the flow point and cause you to experience uneven curing temperatures. Allowing parts to cool too fast may cause dulling of the finish, so leave the part in the oven with the door open for a short period before removing.
The photo right, shows the completed component after installation. This part was coated, baked, re-assembled and installed in about in just over an hour and half. There is simply no better way to a get high quality finish that provides this level of protection in such a short period of time.
Another project we just finished was the Hinge Re-build. In this project, we also used the HotCoat powder coating system to provide a hard, durable finish on our re-built hinges. In the photo to the left, you can see the re-built hinges dressed in a "Satin Black" powder coating material from HotCoat.
The finish on these hinges is very durable and very tough. We found out just how tough the powder coating finish was when we tried to remove it. We missed a weld on one of the hinges and wanted the metal clean for welding. Well, we dropped the part back into our blasting cabinet and hit it with heavy glass bead at 80 psi.....it only dulled the finish. We had to change to a carbon oxide blasting compound to take off the coating. Powder is a tough finish!!
Its important at this point for those who are interested in this process and feel that they would benefit from the best finishes available to the do-yourselfer, to read the complete HotCoat instructions to see how simple the process really is.
From time to time we will be adding new Powder Coating Projects to our "Project" section and we invite you to send us your photo’s and tips on what you have learned while enjoying this fascinating hobby. - CTS