| Re: [GMCnet] What not to do when repainting a 1973 GMC Photo Log [message #138198] |
Tue, 09 August 2011 17:21 |
sgltrac
Messages: 2797
Registered: April 2011
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Abs is probably the most tolerant plastic for painting similar to acrylic. You can spray most topcoats directly onto clean abs. If you are going over existing paint in good condition a scotchbrite scuff pad(red) and then soapy water wash should be sufficient. The water wash will help knock the static out of the plastic which will help with dust and lint. If you are going over lacquer, I would coat with.... Epoxy. Light coats until you achieve a decent film thickness so you don't wake up the lacquer. Once the epoxy has dried enough to not be sticky or still wet, topcoat with whatever you like. If the surface is rough or pitted then a high build 2K primer over the epoxy and sand til smooth and then topcoat.
Laquer is a thermoplastic similar to abs. Lacquer never cures but dries which makes it unstable and prone to chemical attack. Most topcoat manufacturers have a disclaimer about applying their paints over lacquer. The complex shape of the grilles and headlamp doors make them hard to strip by sanding without losing the contour features. Most chemical strippers will melt the abs. So you don't have much to lose by attempting to paint over the lacquer. If the paint reacts then wipe all the paint(original and just applied) off with lacquer thinner on a rag. Just don't stay in one place too long as the abs will soften. Once you have mopped the majority of the paint off, let the thinner dry off and wet sand the residual paint and shallow smears you put in the plastic with the thinner and rag then re-topcoat.
Just my opinion and what I have done in the past and present.
Sully
77 royale
------Original Message------
From: KB
Sender: gmclist-bounces@temp.gmcnet.org
To: gmclist@temp.gmcnet.org
ReplyTo: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] What not to do when repainting a 1973 GMC Photo Log
Sent: Aug 9, 2011 1:42 PM
Wonderful to see the photos. I'm in the middle of the same project on our '75 myself and
hoping for "good enough". Almost anything would be an improvement over what we had!
Any ideas on what to do with the ABS parts prep? The front grill and headlight surrounds
and the old '73 t-skirts I'm reusing are all made of ABS. The '73 was pre-imron, so lacquer
I think. And orange, oh so very, very, bittersweet orange! :-)
Do you think the 2K urethane primers will adhere ok to sanded ABS, or should I use
some epoxy primer on those too? Any problems priming over well-adhered lacquer?
thanks for any ideas,
Karen
1973 23'
1975 26'
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Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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