System Three Varnish

[Farrell]

I've never had an adhesion problem with topcoats on epoxy, but I know sometimes cured epoxy develops a waxy type coat on it. But, cured epoxy needs to be sanded, and good spar varnishes will have some type of solvent they recommend for cleaning the surface during prep. I have made the mistake before - "I always use brand X turpentine and have had good results" then when you use brand Y topcoat you get some kind of incompatibility thing going on. I have found that if the topcoat (paint or varnish) says to use Interlux #333 solvent cleaner, then by golly gosh, I'm going to use Interlux #333 solvent cleaner, and I will experience no problems.

So, my recommendation is to clean with recommended solvent, sand to appropriate grit, and then clean again with recommended solvent. You should have no compatibility problems. I would also make sure that the epoxy was properly mixed and has cured for a week or so at appropriate temperatures.

Terry Farrell
  
----- Original Message ----- 
From: "Delwin D Fandrich" <pianobuilders@olynet.com>
To: <davidlovepianos@earthlink.net>; "Pianotech" <pianotech@ptg.org>
Sent: Saturday, March 01, 2003 11:32 AM
Subject: Re: System Three Varnish


> 
> ----- Original Message -----
> From: "David Love" <davidlovepianos@earthlink.net>
> To: "Pianotech" <pianotech@ptg.org>
> Sent: February 28, 2003 5:50 PM
> Subject: Re: System Three Varnish
> 
> 
> >
> > I'm not sure why the flexibility of the varnish would matter.  Either the
> > board is stiff or it isn't.  In the case of an epoxied board, the epoxy
> > provides the stiffness and the varnish topcoat is not required to
> > contribute additional stiffness.  Nor would it make the epoxy any less
> > stiff by virtue of its flexibility, if it is, in fact, flexible.  I have
> > used varnishes for years on soundboards, usually over a shellac undercoat
> > without detriment.  In this case, since I am stiffening the board with
> > epoxy and System Three makes a varnish that supposedly does not have any
> > compatibility with their epoxy.  I was more wondering about the cosmetic
> > quality.
> 
> 
> David,
> 
> As I said earlier, I've not used System Three varnish. But the compatibility
> issue may be a valid one. I've had one combination of epoxy/varnish give me
> problems. The varnish never did thoroughly dry and had to be stripped off
> and replaced. It also softened the surface of the epoxy. It had to be
> scraped down to hard, clean epoxy. I took it back to just the surface of the
> wood. All in all a real mess. I then recoated and went on. This was some
> years back and the epoxy was an off-brand purchased from a (then) local
> marine supply store. The varnish was purchased at a (then) local paint
> store. I don't remember the brand but it was not one of the major marine
> varnishes. I've subsequently been told that these problems are rare but they
> still can occur. I don't know why they occur or what there is in either
> product that might create the potential problem. The chemists out there are
> welcome to have a go at it.
> 
> My experience with soundboard coatings has convinced me that the physical
> characteristics of the finish material are incidental to the soundboard's
> performance until either their mass or stiffness becomes a significant
> percentage of the whole. In the case of the epoxy coating the stiffness of
> the soundboard system is increased (significantly) and mass is increased
> (slightly). I can't see any common coating material on its own doing either.
> 
> Del
> 
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