DIY POWDER-COATING
Ralph Ferrand on why it’s now possible to do at home.
Back in April at the Stafford Show, I found a stand that was demonstrating a DIY powder coating set-up which tweaked my curiosity: powder coating at home? Sadly at the show their heat source wasn’t working so all they could show was the special gun applying powder, so I couldn’t tell if it was actually any good but editor Bertie was keen for us to give it a go for the benefit of CMM readers. I contacted Electrostatic Magic and told them that I would be interested to test their product out, but would only be truthful about my findings in any reporting. They were enthusiastic about sending me a piece of kit to try, which I usually only find to be the case with purveyors of products that actually work. We shall see! The kit duly arrived and I just had to find the remaining kit to use it with. Number one on the list is a compressor that can output 50psi (3.5 bar) at 1 CFM with at least a six-litre tank. Not a problem, I can turn the regulator down to 50psi. A decent breathing mask is also required, which I have already for using with wet paint. The only thing I didn’t have was an oven and while a domestic oven is fine, they do advise against using the one your missus puts the Sunday roast in. My late mother had an old Baby Belling at her house, so I snaffled that. I popped down to a local discount hardware shop and came back with a large clear storage box to spray into; it’s best to collect all the powder that misses the item you’re coating for re-use. Because I only had a small oven the initial test was going to need to be performed on small parts. I had a couple of brackets for a customer’s bike, but I wanted to try it on something slightly less easy. I have lots of old Z900 handlebar switches, so I thought that coating a set of those might be an interesting challenge. If you take them to any commercial powder coaters they generally ruin them by putting too much thickness on and by omitting the crucial de-gassing process. As with all forms of coatings, be it wet paint or powder, preparation is key and no
form of coating is going to stick to grease or oil. I stripped the switches down, having carefully photographed them to give me a fighting chance of success on reassembly. I decided that glass bead blasting was the easiest way to clean them all up. I then gave them a thorough degreasing with brake cleaner before giving them another good go in the bead blast cabinet. Glass bead blasting provides a great key for the powder coat to adhere to. To be honest I’m not sure whether handlebar switch die castings need degassing or not but I gave them half an hour in the oven anyway. This would also help to ensure that any grease or oil trapped would be given a chance to leach out and be seen. I let them cool down and then gave them a final degreasing with panel wipe and clean paper towel. I checked the temperature of the oven using a thermocouple accessory for my multi-meter, which soon told me that my inheritance had a buggered thermostat. To keep the oven at the correct temperature, I had to keep turning it on and off and vent excess heat out by opening the door! It was a warm day and my workshop was soon like a sauna. The powder came in a half-kilo zip-lock bag and I found that the easiest way to decant it into one of the supplied powder canisters was with a household funnel with the canister very lightly held upright in the bench vice. With a basic kit you get one bag of powder free and I had requested a black satin, which is the most commonly-used in restoring 70s, 80s and 90s bikes. This seems to go a long way and even when I need more it will only cost me £6.99 for another bag. Looking on their website there are all sorts of exciting bright candies and metallics to play with and the most expensive is still only £9.99 a kilo. As someone who regularly buys professional paint, I have to tell you that this is very much cheaper than the two-pack paint I would use as an alternative, which would also require a hardener, primer, thinners, gun wash etc. With this initial test I didn’t really need to mask anything, but I do know that masking materials for powder coating are more expensive and harder to work with than those used with wet paint. As per the simple to follow instructions supplied with the kit I fitted the water trap to the gun and although they include a fitting to attach an airline pipe, I preferred to fit a PCL airline connector, so that I could fit it directly to my air supply. As instructed, I then adjusted the air pressure regulator screw at the bottom of the gun’s handle, while squeezing the trigger in my plastic box/spray booth until a gentle cloud of powder exited the end of the gun. The parts need to be earthed to the gun. There is an earth strap snap stud on the side of the gun and a curly-wurly recoil earth wire is attached to this. The other end has a crock clip to attach it to the workpiece. I made hanging hooks for the workpieces from light aluminium TIG welding rods so that I could attach the earth to these, rather than the parts themselves. Where there were threaded holes I fitted in screws and attached the hooks to those instead, which has the added bonus of masking the threads into the bargain. Essentially, providing the workpiece is electrically connected to the body of the gun, it really doesn’t matter how this is achieved. The kit did come with a wristband to attach to the earth