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topic 33359

Help, paint adhesion problem on HDPE

A discussion started in 2004 and continuing through 2020 so far.
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Q. I am blow molding a HDPE product. I am trying to get paint to stick to the hdpe. I realize that pe is not the best plastic for painting. However, I'm locked in to this material. I am flame treating the material and it works pretty well. However, I want better paint adhesion. SO my question is, How can I increase the surface tension to assure a better paint adhesion? Any ideas would be greatly appreciated.

Joe Nix
Manufacturing - Tulsa, Oklahoma


? Is there a reason why you cannot use HDPE that is pre-colored with a suitable concentrate?

Toby Padfield
Automotive module supplier - Michigan


A. Hello Joe,

Corona discharge in a vacuum chamber will work. Very high start-up costs though. Plasma removes a few angstroms from the surface giving the paint something to "bite" on.

Trent Kaufman
Trent Kaufman
   electroplater - Galva, Illinois


A. Hi Joe

What Toby said is very sensible ... but then you, like myriads of others, never give full info.

One idea is to use, if available, a 'waxed' paint product. We used to mark Pe containers with wax crayons (showing liquid/gallonage levels) and then HEAT those markings ... and as Pe is a long chain wax olefin, ah, those markings would become indelibly fused in place.

Anyhow, food for thought....and yes, Pe like PP, unless specially treated (expensive !) won't allow for a good painted surface as you have found out!

If, if, if your final product was, say, for the sake of argument, a round section, then use a good paint with a high shrinking factor (eg. 2 component urethane) and lo and behold, it would 'lock' itself in place.

Food for thought, anyhow.

freeman newton portrait
Freeman Newton [dec.]
White Rock, British Columbia, Canada

(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).

December 9, 2011

A. Hey, Joe

Apply Primer and then PU paint. PU paint can be Air dried.. or you can pass thru 50 degree temp. This is advisable for small production

- Mumbai, India

August 13, 2020

A. D-I-Y HDPE Primer:
Outside or with protective mask, melt semi-transparent glue sticks in lacquer thinner over electric burner, stirring continually. If too thick, add more lacquer thinner. Will congeal as it cools, so you must warm it before application.

Kandis Mueller
- Payson, Arizona

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