# Powder Coat Not Sticking To Primer



## Clockwork Bikes (Jun 17, 2006)

I just had a frame blasted, primed and painted with Dupont Alesta RAL 5024 and the 5024 did not stick to the primer. After facing the HT you could peel it off with a finger nail from the edge. I've never had this happen before. It was backed at 400* for 18 minutes. Not long enough? The primer was sanded prior to aplying the 5024. Is primer even necessary? Any insights would be appreciated.

Thanks, Joel


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## Yogii (Jun 5, 2008)

Sorry to be a jerk about it......does the world need another blue bicycle frame?
Carolina Blue should not be allowed outside of the state.
good luck


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## D.F.L. (Jan 3, 2004)

I'm afraid I may be just as helpful, but...

Are you talking powder primer? You use the word 'paint' which throws me off a bit.

My coaters have never recommended powder primer. I know that each successive coat of powder inhibits adhesion of the dry powder (the static charge) and encourages orange-peel, two things that coaters hate to deal with.

And why did you sand the primer? Was it uneven?


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## Clockwork Bikes (Jun 17, 2006)

The primer was a powder coat gray zinc. I think the primer was baked too long. The next round will not have primer. And the customer can pick whatever color they please.

Thanks, Joel


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## shiggy (Dec 19, 1998)

Clockwork Bikes said:


> The primer was a powder coat gray zinc. I think the primer was baked too long. The next round will not have primer. And the customer can pick whatever color they please.
> 
> Thanks, Joel


The too-long first bake sound right. This can be overcome sometimes if you pop the frame in the oven for ~60 seconds before spraying the top coat.


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## Rody (Sep 10, 2005)

Joel,

you and Shig are right on the money...the frame was baked too long.

When I lay down the Dupont primer, I run a half cure on the primer at about 380 degrees and then run it back through the color coat while still warm and soft. I also need to turn up the voltage to about 95 so that I have 70-75 at the gun when spraying to have proper adhesion for the second coat.

cheers,

rody


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## Clockwork Bikes (Jun 17, 2006)

The new paint job looks great (for powder). http://www.clockworkbikes.com/XXIX_kershaw_1.html

1. Fresh sand blast.
2. Bare frame in oven.
3. Shot the tight spots while the frame was hot.
4. Let the frame cool and shot the whole thing.
5. Backed for 10 minutes at 400*.

Thanks for everybody's help,

Joel


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## shiggy (Dec 19, 1998)

Clockwork Bikes said:


> The new paint job looks great (for powder). http://www.clockworkbikes.com/XXIX_kershaw_1.html
> 
> 1. Fresh sand blast.
> 2. Bare frame in oven.
> ...


A 10 minute final bake sounds too short.


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## Clockwork Bikes (Jun 17, 2006)

I did a test tube and wacked it up pretty good with the dull side of my knife and it held up. It also didn't rub off with acetone.

-Joel


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