As any enthusiast knows, powder coating produces a finish more lustrous and durable than any paint. But, powder coating can also pose some challenges – the part must be stripped down to bare metal and, due to the nature of the process, small recessed areas are practically impossible to coat. Unless you are the proud owner of a HotCoat Dual-Voltage powder coating gun, in which case you sneered and thought, “Ha! Amateurs!” as you read the previous sentence.
The power of the Dual-Voltage gun’s versatility stems from the heart of the powder coating process and involves a fascinating bit of physics. The “powder” in powder coating is actually a mixture of finely ground resin and pigment. The gun ionizes these particles, which are then pushed out of the gun by compressed air and accelerated towards and held onto the part by powerful electrostatic forces. This is half of the reason why you can’t conventionally powder coat wood, plastic, or other materials which act as insulators; the other half is that many plastics will melt when cured in an oven and wood will combust.
The high voltage setting (25,000 V) produces a Faraday Cage effect, an electrostatic condition where charges on the exterior of a surface rearrange themselves to cancel out charges on the interior. This prevents the powder from adhering to the inner, uncharged surfaces in small recessed areas, such as the center of the control arm that we used in this video. However, the effect of the Faraday Cage is reduced as the voltage is lowered –here, from 25,000 V to 15,000 V – because the “strength” of the electric field is proportional to the voltage. If you're interested in a demonstration of a Faraday cage, you can check out a great demonstration by the folks at MIT's TechTV here.
Using the Dual-Voltage gun, you simply flip a switch to alternate between the high and low voltage settings. Evan, the newest member of our Eastwood team, and I created a video to show you exactly what sort of power the Dual-Voltage gun brings to the garage. Check it out below (as usual, click here for full 720p goodness).
JR, the mind behind the Dual-Voltage gun, brought in the control arm that you see in the video and it was absolutely filthy – it had been coated with several different substances at various points in its lifetime, including a tough rubberized undercoating. Evan really had his work cut out for him removing these layers so that we could get a surface suitable for powder coating – he alternated between blasting the arm in our blast cabinet and applying Under Gone. After two of these cycles, he blasted the arm one final time, washed it with After Blast, and we were ready to powder. Per JR’s plan for these arms, we used Gloss Black powder.