Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Default Removing powder coating from ali sheet?


Chris Wilson wrote:
I am re building a tube frame race car panelled in ali sheets that

were
powder coated pre riveting. If I un-rivet the panels, many of which

are
quite intricately formed, is there a safe way to remove powder

coating
from fairly soft grade alloy sheet? I then want to re powder coat

them,
probably in a different colour to the black which they are now. Most
have had some abrasion that has rubbed through the powder coating,

some
have a bit of fretting around the odd rivet.

Thanks.


--
Best regards,
Chris.


Chemical stripping is probably the easiest, but not exactly the safest.

When I was working in the aluminum finishing plant, we used to get some
dud parts that needed to go around again. We used a large tank of
methylene chloride-based stripper with a water cover to do the job, it
usually took about 4 hours to get the powder coat loose enough to hose
off so they could go through the powder-coat process again. This was on
polyester and epoxy coated parts. I've not checked availability lately,
but locally I could get aircraft finish stripper from a auto body
supply shop, this was about the most potent stripper that was readily
available without going to a chemical warehouse and compounding my own.
Gloves and eye protection mandatory, chemical boots and suit
recommended. It should take off just about any organic coating.

Be aware that powder coating needs about 450 degrees F to cure,
probably OK for your panels, might not be good for load-bearing items,
though. You might want to consider going to a regular automotive
finish system after stripping, it'd probably be easier to maintain and
durability would probably be as good or better than powder coating.
Stan

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RoyJ
 
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I'd check with a medium to high volume powder coating facility. They
have their share of dud runs, need to do this all the time.

I'd second the notion of using a standard auto refinishing system rather
than powder coat. My race car gang had their whole frame powder coated
over my mild objections. Between the runs due to poor drainage and their
inability to make up their collective minds on a few details like how to
mount the brake pedals, it never made it to the track in pristine
condition. And after the tech inspector had his say, there were a few
more brackets and welding that needed to be touched up.

Chris Wilson wrote:
I am re building a tube frame race car panelled in ali sheets that were
powder coated pre riveting. If I un-rivet the panels, many of which are
quite intricately formed, is there a safe way to remove powder coating
from fairly soft grade alloy sheet? I then want to re powder coat them,
probably in a different colour to the black which they are now. Most
have had some abrasion that has rubbed through the powder coating, some
have a bit of fretting around the odd rivet.

Thanks.


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Roger Shoaf
 
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"Chris Wilson" wrote in message
...
I am re building a tube frame race car panelled in ali sheets that were
powder coated pre riveting. If I un-rivet the panels, many of which are
quite intricately formed, is there a safe way to remove powder coating
from fairly soft grade alloy sheet? I then want to re powder coat them,
probably in a different colour to the black which they are now. Most
have had some abrasion that has rubbed through the powder coating, some
have a bit of fretting around the odd rivet.

Thanks.


--
Best regards,
Chris.


I got a hold of some powder coated box tubing that I was going to weld into
a frame. Even after an overnight soak in a methelyne chloride based
stripper, (Jasco) I ended up grinding it off.

Good luck.

--

Roger Shoaf

About the time I had mastered getting the toothpaste back in the tube, then
they come up with this striped stuff.


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Bob Engelhardt
 
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I have burned it off, using the burner from my casting furnace. But
that's not something that you'd want to do with aluminum sheet. Bob
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Roger Shoaf wrote:
"Chris Wilson" wrote in message
...
I am re building a tube frame race car panelled in ali sheets that

were
powder coated pre riveting. If I un-rivet the panels, many of which

are
quite intricately formed, is there a safe way to remove powder

coating
from fairly soft grade alloy sheet? I then want to re powder coat

them,
probably in a different colour to the black which they are now.

Most
have had some abrasion that has rubbed through the powder coating,

some
have a bit of fretting around the odd rivet.

Thanks.


--
Best regards,
Chris.


I got a hold of some powder coated box tubing that I was going to

weld into
a frame. Even after an overnight soak in a methelyne chloride based
stripper, (Jasco) I ended up grinding it off.

Good luck.

--

Roger Shoaf


There's a lot of different grades of paint stripper, the grades you can
get at the hardware store usually has very little of the good stuff in
it. The more you spend, the higher the concentration of methylene
chloride. The aircraft finish stripper I was using had a concentration
of about 30% methylene chloride and was about $30/gallon. The hardware
store stuff didn't even start working on the car finish I was trying to
remove. 15 minutes with the good stuff and the finish popped off with
a sound like frying bacon. The stuff we got at the finishing plant was
over 75% methylene chloride, I don't know what that cost per barrel.
There was probably 400 gallons in that tank, though.

Stan

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