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paint over powdercoat

Old 01-20-17, 09:17 AM
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paint over powdercoat

I'm considering a frame that is powdercoated. Ideally, I'd like to strip that off and paint the frame as it should be, in its full regalia. Is stripping powdercoat hard?

Or can I/should I just paint over powdercoat?
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Old 01-20-17, 09:21 AM
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Just like any other paint prep: scuff sand the powdercoat with something like 180 or 200, prime with a filler primer, and finish as you normally would.
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Old 01-20-17, 09:37 AM
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What material is the frame made of? Expect the need to periodically touch up the now raw surface if it's not TI. Also don't be surprised at what you find under the paint. Paint is like wall paper, sometimes it hides stuff... Andy.
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Old 01-20-17, 10:31 AM
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Send it to be blasted.. A powder coat job was first blasted to bare metal.

but if the PC is sound, roughen the surface so the paint color will stick .. aka "tooth", and paint over it.
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Old 01-20-17, 10:38 AM
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Personally, I always want to start with a bare frame. You just get a better final product.

That said, removing powder coat is a time consuming HUGE pain in the butt. I've done it. Sandblasting alone does not do the job. The friction raises the temperature of the powder coat which just causes it to become more adhesive, similar to cooking it again. Regular paint stripper won't even touch it. You'll need an "Aircraft Stripper" and even those are only mildly effective. Removal is best done by applying the aircraft stripper to soften and weaken the finish, then hit it with a sandblaster when the timing is right. Repeat. Repeat. It's a messy hassle.

I did a frame 100% manually with aircraft stripper and hand tools. Took about 12 hours.

Aircraft stripper is nasty stuff. If you decide to use it, follow the safety precautions.

Last edited by SquidPuppet; 01-20-17 at 10:45 AM.
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Old 01-20-17, 10:41 AM
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Not to hijack, but is scuffing enough if one just wanted to paint the headtube a different color or put an accent panel on the seat tube of a powdercoated frame?
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Old 01-20-17, 10:42 AM
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It's an 853 frame. The powdercoat is sound (in fact, its new), but not the color I want (I want a two-tone job, with decals, and a clearcoat). So I think 180 wet/dry paper (used wet) to get the surface clean and roughed up a bit, as you suggest, then will proceed with Imron.
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Old 01-20-17, 10:52 AM
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Originally Posted by SquidPuppet View Post
I did a frame 100% manually with aircraft stripper and hand tools. Took about 12 hours.
Well, that answered one question. You are apparently one determined guy, though.

Originally Posted by SquidPuppet View Post
Personally, I always want to start with a bare frame. You just get a better final product.
I agree, but your 12 hour experience may mean a re-think of my refinishing dreams!

Thanks!
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Old 01-20-17, 11:00 AM
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Originally Posted by WizardOfBoz View Post
Well, that answered one question. You are apparently one determined guy, though.


I agree, but your 12 hour experience may mean a re-think of my refinishing dreams!

Thanks!

And then I turned right around and re-powder coated it again.

I love PC, I just wanted a different color.
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Old 01-23-17, 01:43 PM
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Originally Posted by SquidPuppet View Post
Personally, I always want to start with a bare frame. You just get a better final product.

That said, removing powder coat is a time consuming HUGE pain in the butt. I've done it. Sandblasting alone does not do the job. The friction raises the temperature of the powder coat which just causes it to become more adhesive, similar to cooking it again. Regular paint stripper won't even touch it. You'll need an "Aircraft Stripper" and even those are only mildly effective. Removal is best done by applying the aircraft stripper to soften and weaken the finish, then hit it with a sandblaster when the timing is right. Repeat. Repeat. It's a messy hassle.

I did a frame 100% manually with aircraft stripper and hand tools. Took about 12 hours.

Aircraft stripper is nasty stuff. If you decide to use it, follow the safety precautions.
This doesn't sound right. I had a frame re-powder coated a couple of years ago, and media blasting (which was done by the powder coater) couldn't have been more than $20 or $30 additional. No way they could stay in business if it were a 12 hour job!

Mike
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Old 01-23-17, 02:00 PM
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Originally Posted by dubes View Post
This doesn't sound right. I had a frame re-powder coated a couple of years ago, and media blasting (which was done by the powder coater) couldn't have been more than $20 or $30 additional. No way they could stay in business if it were a 12 hour job!

Mike

Read my post again. I (ME) removed powder coating using chemicals and HAND HELD tools. Scraping etc, no blasting.

A powder shop will use the chemicals in conjunction with blasting. Which is still a somewhat time consuming and VERY messy job.

Have you every tried to remove powder coat with a media blaster? I have. Without chemicals you will be fighting a never ending battle.
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Old 01-23-17, 09:02 PM
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Just found additional info.

One site advocates Benco B-17 paint remover for powercoat removal.
Powder Coating: The Complete Guide: Stripping Powder Coat

Could you use CO2 (dry ice) to blast the powdercoat off? This site shows an examples of dry ice blasting on powdercoat:

Here is a dustless blaster using garnet. The dustless blaster uses water with the abrasive to cool the surface. The video addresses the problem squidpuppet identified. Seemed to work (pretty salesy, but informative):
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Old 01-24-17, 01:53 PM
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Originally Posted by WizardOfBoz View Post
Just found additional info.

One site advocates Benco B-17 paint remover for powercoat removal.
Just an FYI for anyone following this topic. The active ingredient in "Aircraft Stripper" is methylene chloride. That's the only ingredient that matters. It's what bath tub and shower refinishers used to use years ago to strip tubs and showers before they started getting fatal respiratory tract damage. The higher the concentration the faster and more effectively it will work. The Benco B-17 product is 75-80% methylene chloride. I did extensive research on this before stripping my frame and fork. I found a product that is 85% methylene chloride. It's called Dad's Easy Spray Stain, Paint and Varnish Remover. It's so nasty a few states won't allow it to cross their borders.

Anyway. The Benco stuff says 20 minutes. LMAO. Nope, no way, no how.

Using methylene chloride on paint is great. The paint bubbles and can be peeled off in sheets. Not the case with powder coat. On first application it begins to weaken the PC. BEGINS. The second application weakens it more. The PC never bubbles or peels off. It only (after numerous applications of methylene chloride) gets soft enough that it can be scraped off with a putty knife, screwdrivers, razor blades, picks and steel wool. The methylene chloride is only active for a few minutes so numerous applications and scraping sessions are required.

I did about 3 hours in the late afternoon for four days. Long tedious mind numbing labor.

Be warned. If you don't respect methylene chloride it will send you to the hospital. It'll burn your skin and tissue all the way to the bone, fast. It will burn and collapse lungs. Eyes? Let's not talk about it.
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Old 01-24-17, 03:11 PM
  #14  
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I worked with methlyene chloride (dichloromethane) extensively in the circuit board printing industry.

Not trying to contradict you Squid and I don't know the concentration we used but guys cleaned screen printing ink with it all day long, with and without rubber gloves. They got it all over their hands and skin, had it in pump canisters and even atomized it in spray bottles spraying it everywhere. It felt like alcohol, evaporated quickly. Has a sweet smell.

Again, I've no idea of the concentration.

It is seriously nasty stuff though. No doubt about that. I shudder to think of the consequences of long term exposure. Some of the old timers washed their hands with the stuff at the end of every shift for decades and poured it down the drain.

I was the weird guy who wore safety goggles and rubber gloves. They accused me of paranoia, trying to make them look like fools...

Last edited by TimothyH; 01-24-17 at 03:15 PM.
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Old 01-24-17, 06:52 PM
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Originally Posted by TimothyH View Post
I worked with methlyene chloride (dichloromethane) extensively in the circuit board printing industry.

Not trying to contradict you Squid and I don't know the concentration we used but guys cleaned screen printing ink with it all day long, with and without rubber gloves. They got it all over their hands and skin, had it in pump canisters and even atomized it in spray bottles spraying it everywhere. It felt like alcohol, evaporated quickly. Has a sweet smell.

Again, I've no idea of the concentration.

It is seriously nasty stuff though. No doubt about that. I shudder to think of the consequences of long term exposure. Some of the old timers washed their hands with the stuff at the end of every shift for decades and poured it down the drain.

I was the weird guy who wore safety goggles and rubber gloves. They accused me of paranoia, trying to make them look like fools...

The concentration was no doubt low. I chatted with a guy on line who was stripping PC with the strong stuff and didn't wear gloves. INSTANT and progressive skin loss. Raced to the ER. The doctors had difficulty stopping it's advancement. Needed plastic surgery to fill the holes. Permanent nerve damage.

From OSHA's site.

BRIEF INCIDENT DESCRIPTION
A temporary worker died while removing the coating from a bathtub
in a residential building. The worker was alone in a small bathroom
where he poured paint remover containing 85-90% methylene
chloride into the bathtub and began scraping. The only ventilation
was a partially open window. Two hours later, the apartment
resident found the worker unconscious and slumped over the
bathtub. The resident pulled the worker away from the bathtub
and called an ambulance. The worker was taken to the hospital,
where attempts to resuscitate him were unsuccessful. The coroner
determined that asphyxiation, combined with acute methylene
chloride toxicity, caused the workerís death.

Normal masks with filters are useless. I read a thing where a Lab tested the highest quality filter for it's ability to block the carcinogens. It failed in something like 20 minutes because the fumes MELTED the filter. You have to wear SCUBA gear if you use it indoors.
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Old 01-24-17, 06:58 PM
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Formby's Furniture Refinisher is like that but not as bad. Will burn if it gets on your skin to the point of pretty bad pain.

I don't know what the OP should do. My powder coated frame will be thrown in the garbage when it is done but it is also old and not collectible.
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