[TheForge] OT sort of Powder Coating

[ries]

I have never done it myself, but I have been paying people to do it  
since about 1988.
I have sent several powder coaters kids to college.
We used to do production pieces like candlesticks and soap dishes,  
where we might do 200 at a time, or a dozen chairs, or sculptural  
elements as big as 20 feet long.

Things I learned:

Sandblasting is good. Not essential, but it sure doesnt hurt,  
especially on hot rolled. We did some production pieces for a few  
years made from rebar (chairs, small tables, and so on) and it all  
needed to be blasted.

Cold rolled can be run without blasting, but it needs to be really  
clean.
Wiping down with alchohol or a solvent will work.

All the pros use phosphate pre-dip systems- The vast majority of my  
stuff had this done to it- my last guy had a 5 tank system- a mild  
etch, then rinse, then phosphate, then rinse again- cant remember  
what the last one was.
Anyway, the point is, the stuff needs to be REALLY clean.

For clearcoated stuff, we would fine sand or wire brush it right  
before blasting, then handle with white cotton gloves.

Aluminum, especially castings, but not only, needs to be preheated at  
300 to 400 degrees for a good 20 minutes first- otherwise, moisture  
always shows up and makes bubbles and pinholes.

Good powder is expensive- I mostly used Tiger Drylac, Cardinal, and  
the major brands just for stuff like Black Wrinkle or plain colors-  
for the fancy stuff, the best, most distinctive colors and textures  
come from Prismatic-
http://www.nicindustries.com/prismatic_powders.php

they cost a lot more per pound than places like Eastwood, but they  
are really worth it.

I recommend using textures or wrinkles in most cases- they wear much  
better, hide scratches and handling marks.
Gloss finishes are the worst, in terms of fragility- Powder is not as  
tough as something like laquer, its pretty easy to ruin a gloss finish.

There is no touchup with powder- if you screw up, you need to remove  
it, and start over- and it aint easy to get it off. The pro shops I  
dealt with use a 2000 degree burnout oven- which, since they did  
things like furniture, was big- it had a little railroad track going  
in it for a dolly about 4 feet square. It does not want to sandblast  
off without being burned first- and the fumes are nasty. You  can, in  
a pinch, use a rosebud, but it will probably shorten your life by a  
few months every time.
My old industrial sandblaster in LA, who had something like 3  
compressors, each 200hp, and air hoses as big as your arm, flat out  
refused to sandblast powdercoating, as nobody would ever want to pay  
what it really cost, as it took SO long.

Best type of oven is one you can roll a cart into- then you can hang  
the parts, shoot em, and roll it right in.
I like to deal with guys who have 20' x 10' x 10' ovens, as I tend to  
do big stuff- and even with chairs, you cant economically do em if  
you can only do one part every half hour, so they would rack up a  
whole dozen or two at a time.

For itty bitty stuff, yeah, you could use an old home oven- if time  
is not a concern. But if you get into doing it much, you are going to  
want a bigger oven.

The $200 guns work. Just like a $500 Harbor Freight lathe will work.  
But just like a real machinist will want a $20,000 used Monarch, a  
real powder coater will spend $5000 and up on a decent pro gun.  
Partly its long life, ease of use, and volume, but the real guns do a  
better job as well.
So dont expect to get the greatest results from those little guns.
Clean, dry air, of course, is a must.

If you are doing the occasional, jewelry sized object, and dont mind  
fussing, then you may have success with the cheapo route.

If you are doing much for resale, and any kind of volume, I think you  
will quickly find its worth it to use a pro shop.
The average guy I dealt with ( 5 different big shops over the last 25  
years- In LA, Ventura, and couple up here in Washington)
had well over $100,000 invested in equipment.

Ries






On Mar 18, 2007, at 11:28 AM, Jerry Smith wrote:

Folks,

Do we have any one out there who does powder coating?
I wan to learn how to do it, and also how to avoid the
mistakes.

I don't have the gun or the basic kit, but I do have a
compressor and a good size oven.

Jerry
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Ries Niemi
Industrial Artist
http://www.riesniemi.com/