Multiple Coat and Clear Coats

[usmcmaw]

I'm building my oven and now starting to look for a gun. As you can see from my web site, www.usm-c.com I do a bit of metal art. Currently, my powder coater put on a zinc primer, then either copper or silver vein and finally a clear coat finish.

#1. Should I have a separate gun for the application of clear coat?

#2. I'm looking at a used 100KV gun, do I need that much KV?

#3. Is there a recommended KV for coats 1, 2 and 3 or does that change for different types of powder?

I've been building my oven for 3 days now and have it about 75% done. This group has been so helpful which I really appreciate. I can't offer much powder coating wisdom, but if I can help anyone in the Southern California area, I have a 4' X 8' CNC plasma table and a CNC mill and lathe.

Thanks.

[sdold]

Hi Glen! I'm not an expert, and I would like to hear what they have to say. I'm just someone who has been doing it as a hobby for about a year. I recently built a 4X3X2 oven and have been doing bicycle frames and parts, and some airplane stuff like rudder pedals and flap handles.

I have a 25 KV gun. When shooting a clear over a standard or metallic color, it's not always enough to put a second coat on reliably. Sometimes it works, but many times I end up having to heat the part back up to around 200 in the oven and shoot the clear on while it's cooling down. I think the problem is that there isn't enough of a charge on the paint to attract it reliably through an existing coat. I've tried lowering the voltage, changing air flow rates, ensuring solid grounds and various other techniques and nothing really helps that much. Interestingly, I have not had this problem on the solid metal-like powders (aluminum, "chrome" variations, etc.), the second (clear) coat seems to cover well over these.

Shooting while hot is my work-around. I do this to bicycle frames and it works extremely well. I think it would well for your stuff if you could get it out of the oven and shoot it within a few minutes, before it cools down too much.

I think the idea of a separate gun for clear is great, it would sure save a lot of cleaning hassles.

It would be great to hear from someone who has used both low-voltage guns and 100 KV guns and can tell us what the difference is in ease of second-coat coverage.

Steve

[FSTFBDY]

There's a bigg diff in hi/lo KV

I can't help from exp. with a Hobby gun as I use a NORDSON SURE COAT. but as said above You should be fine shooting your clear while the part is warm (120-150* range) or even right out of the oven. I do this ALL the time. Its just that much easier and quicker even with a PRO gun.

It would be nice to have 2 guns. As you said one for clear only again would make doing things much quicker. but is it worth the cost of another gun? It only takes a couple of minutes to clean the gun and put a different cup on while you have the oven loaded up.

Another thing you could do if caswell has hoppers for the hobby gun would be have extra hoses and a hopper with clear. This way you just blow the gun out and put clear hopper and hoses on. With mu nordson I have a few different hoses. one for clear only. then blacks,browns,dark colors. Then silvers,metalics, and Then whites. etc..

Hope some of my rambling help ya.