I needed to put winter tires on my car and rather than go through the hassle of going to a tire shop to have the tires unmounted and remounted I decided to get a dedicated winter set-up.
In this write-up I will show the process I used to strip, sand, and powder coat a set of alloy wheels with a little time and help from the folks at Techshop. The project can be completed over a weekend or two based on experience in the methods discussed.
Note: This write- up is meant only to show the steps required to refinish wheels, it is not a detailed instruction manual. Please follow the proper instructions and safety precautions when using the materials, tools, and equipment mentioned here.
Step 1: Tools and Materials
I was looking for an OEM set of wheels as I feel they are of a higher quality than cheap aftermarket wheels, if there is any truth to this I don't know. The set I found was older and beat up, but cheap enough that I could try my hand at a little DIY refinishing and powder coating over at Techshop.
Tools I used:
Chemical resistant gloves
Nitrile gloves (for final washing NOT chemicals)
Respirator (rated for chemical exposure)
Non-marring plastic scraper set
Set of brass brushes with drill attachment
1-2 quarts "Aircraft" stripper
Powder Coat (.5-1lb) I did just the faces of four 17" wheels and used right about half a pound.
Step 2: Stripping the Old Finish
Before the wheel can be powder coated the original finish needs to be removed down to the bare aluminum. My first attempt at this was to throw it in the sandblasting booth, but I quickly found that the finish was much too durable for this to work.
The first picture shows the wheel in its original state and the post sandblasting version next to it. The picture makes the original state look MUCH better than in person, you can see the after version wheel has lost its sheen but the finish is still intact.
When sandblasting didn't work I resorted to a chemical stripper. I used a product called "Aircraft Stripper" that I found at an auto parts store, but anything that claims to remove epoxy & paint from metal should work.
Apply the stripper to the wheel following the directions on the label, it starts to work very quickly with the paint visibly bubbling after just a few minutes. After waiting the directed amount of time I used a non marring scraper to remove the paint from the wheel, plastic is recommended as steel can gouge the softer alloy wheel.
A few tips when using the stripper:
1. Wear a mask rated for chemical strippers. There are disposable versions, but I personally feel the larger masks with replaceable filters are more comfortable.
2. Do NOT use nitrile gloves, the chemicals will react with the gloves and can cause chemical burns through the glove
3.Work in a well ventilated, but heated area. The stripper doesn't work in cold weather, I tried in the low 30's and it just sat there.
4. Strip in stages first the paint, then the primer. It is much easier to remove the primer when the stripper has been applied directly to it
5. Work in sections to avoid missing spots, I did half a wheel at a time.
There were a few spots of primer that refused to come off, as well as awkward spots such as the recesses for the lug nuts. For these areas I used either a 3" wire wheel or a 2" wire cup. The cup worked especially well in the lug nut areas.
When finished rinse the wheel and check for any missed areas, be very thorough as the powder will not stick to the old finish.
At this point the wheel should have a finish resembling the picture 2
Step 3: Cleaning and Prep
Once the wheels have been washed to remove the stripper and dried completely they are ready to go into the blasting booth. Sandblasting at this stage is meant to give a rough, uniform surface for the powder coat to adhere to.
Set up the booth for aluminium and start blasting, once the entire surface of the wheel is hit it is done.
After all four wheels are finished, brush off any excess media and take the wheels to a sink for the final wash.
Using rubber gloves and a degreaser, I used Simple Green but similar products should work, scrub the wheels. The idea is to remove any embedded media, dirt, finger prints, basically any foreign materials from the surface of the wheel. Thoroughly rinse the wheels when finished.
Before starting the washing its a good idea to start preheating the oven you will be using to cure the powder coat. Most powders require a temperature of ~400 degrees F and an oven large enough to accommodate four wheels will take a while to get up to temperature. Be sure to check for anything left in the oven!
Step 4: Powder Coating
After the final washing put the wheels into the preheated oven to completely dry them, this will also allow any other contaminants to off-gas prior to coating. After 5-10 mins remove the wheels, using gloves as they will be very hot, its also important to avoid touching any areas that will be coated.
To help make coating easier I placed the wheels on a rotating platform, it was a bit small so I used two metal bars to extend the platform. I placed the ground strap on the back of the wheel making sure to clamp it to bare metal and away from any areas that I wanted to coat.
Using the 25kV setting and ~12psi of air pressure I coated the wheel, rotating it to hit any missed areas. At this stage the thoroughness of the striping and cleaning will be emphasized, as any missed areas will stick out.
After coating all four wheels and checking for any missed or thin spots the wheels are ready to put in the oven.
A few tips for placing the wheels in the oven:
1. Temporarily shut-off any ventilation fans in the room, a lot of heat will escape from the oven when the door is opened, putting the room under vacuum (vent fans) will increase the loss.
2. Increase the oven temperature to accommodate for some heat loss, I lost almost 100 degrees in the time it took to place the wheels and close the door. Oven temp can be set back to recommended levels once the door is shut.
3. If using racks, place the wheels on the top rack first to avoid knocking anything down onto the wheels below. Remove them in reverse order.
Step 5: Mounted!
I had the tires mounted and balanced at a tire shop near my house, overall I am very happy with how they turned out.
The tips I mentioned were mostly found out the hard way, hopefully they will save a few headaches.
Thanks for reading!
I made (did?) it at Techshop!