On Jul 5, 7:13*am, mkr5000 wrote:
I just bought one of these harbor freight powder guns and some of their coating.

Have never done this before and was wondering how much overspray can I expect with this?

I want to build a nice, small chamber to spray into (and maybe be able to recover some of the powder?) (or is that worth the effort?)

How much powder do you end up wasting?

For example, HF sells a 4.99 (looks like a pint) container -- what percentage gets on the piece? *(I'm sure technique matters but "generally"). *thanks

The motorhome factory that I worked at used powder coating on their
trim parts, the booth that they did it in had a sloped bottom so any
overage could be removed and reused. At one time, the bag house
reclaim was reused, too, but that was before my time. Apparently it
clogged the guns up, so they just put it in a drum to be sent back to
the manufacturer for recycle. As far as wastage, more went on the
parts than was removed by the bag house or fell on the floor. They
usually went through a drum a week and if they had 10-15 pounds of
recycle, I'd be surprised.

The cure is the key, though. You need to heat up the part slow enough
to fuse the powder onto the part, not just fuse the surface. They had
a big oven with a U-shaped conveyor to run the parts through, slow
heat-up, slow cool down, took about 20 minutes from start to finish.
When properly done, a nickel wouldn't remove any finish when an edge
of it was rubbed on the surface, a swipe with an MEK-soaked Kimwipe
didn't remove any finish and the part could be bent double without the
finish flaking off.

Because it's done with high voltage static attraction, if you've got
any sharp edges on your parts, they'll get extra buildup. It doesn't
work too well for closed internal spaces for that reason, either.
Don't expect to use it on close-toleranced moving parts and keep those
tolerances.

If you expect to use it on automotive body parts that are steel and
exposed to salt spray, you might want a rethink. The coating lasts a
looong time, but once the steel starts to rust because the coating
finally got penetrated, it'll go fast. There's no such thing as
touchup with it, either, you have to strip the whole coating,
remediate the rust and recoat. We had a big tank with water-covered
methylene chloride stripper to redo the oopsies at the plant. Took
most of a day soaking just to get it to the point where it would come
off in strips. The residue had to be drummed and shipped to the dump
as toxic waste, too.

Stan