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Re: Paint hardness/Painting

To: british-cars@autox.team.net
Subject: Re: Paint hardness/Painting
From: "Jerry Kaidor" <jerry_kaidor@engtwomac.synoptics.com>
Date: 25 Sep 92 08:54:59 U
   RE>Paint hardness/Painting tec
Rob Neilson asks why his paint is so easy to chip....

  Rob,

     Ordinary non-catalyzed enamel takes at least a month or three to cure. 
"Dried" is not the same as "cured".  Reactions take place in the paint film
that make it much tougher.  This is why you can't buff out new non-catalyzed
enamel:  it's not hard enough.  

    Also, I see you're using a primer out of paint cans.  It's probably acrylic
lacquer primer/surfacer.   Such primer is not very hard.   Soft primer under a
hard topcoat is very prone to chipping, because the paint does not have good
support under it.  Imagine a coat of eggshell over a sponge!

 The most chip-resistant system would be some kind of extremely hard primer,
under a coat of relatively soft and flexible paint.  An example of this would
be Dupont Imron over PPG DP-40.  The Imron goes on like liquid plastic, and is
soft and flexible.  The DP-40 primer, on the other hand, dries hard as a rock.

          - Jerry

 
    



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