How do you subdue silicone in a finish?

[Mark Potter]

It is certainly true that "fish-eye" preventer works, but I have always avoided its use for the simple reason that once you use it, you ALWAYS have to use it because it contaminates your spray system forever.  If you want the ability to spray other finishes thru the same equipment it should be avoided at all costs, IMHO.
   
  I have yet to encounter a contaminated surface that shellac will not adhere to, thereby sealing off the contaminates for further finishing.  In all but one case a 2lb cut of shellac - one coat - has been adequate to prevent problems.  A second coat of 2 lb. cut would certainly guarantee success, even the most difficult situations.  If spraying lacquer, there is no need to sand the surface of the shellac for adhesion, and I tend to think it is better left unsanded if you are overly concerned about silicone contamination causing problems with lacquer flow-out.
   
  Neither am I a big fan of building up a thick pore-filling film of shellac if lacquer is to be used for the top-coats.  The differences in the flex of the 2 finishes is likely to cause premature cracking, crazing, or other maladies.
   
  Using dewaxed shellac is preferred, although if top-coating with lacquer this doesn't seem to be an issue.
   
  Mark Potter

Thomas Cole <tcole at cruzio.com> wrote:
  I haven't had any luck trying to "neutralize" or wash out silicone oil 
with solvents, including acetone. The usual fix is to put a little 
silicone (fish eye preventer) into what you're spraying.

I just found an article on line that advises against fish eye preventer 
and advocates ammonia to clean a contaminated surface. It might be worth 
a try.

Tom Cole

William Benjamin wrote:

>Have you tried neutralizing with paint thinner?
>
>William
>
>
>
>
>PIANO BOUTIQUE
>William Benjamin
>Piano Tuner Extraordinaire
>www.pianoboutique.biz
>The tuner alone,
>preserves the tone.
> 
>-----Original Message-----
>From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
>Of gordon stelter
>Sent: Wednesday, March 15, 2006 11:21 AM
>To: Pianotech List
>Subject: How do you subdue silicone in a finish?
>
>Dear List,
> I'm trying to put a proper decal ( not mailbox
>letters ) on the keycover of an 1880 Chickering. From
>the ripples and fisheyes in the existing lacquer, it
>is evident that prior to being poorly refinished,
>silicone-contining polishes were used. 
> I wet sanded ( 600 grit silicone carbide with
>naptha ) the existing finish flat, then tried to spray
>a base coat of Deft lacquer, and it fisheyed all over
>again. So I wet sanded it again, and tried spray
>shellac. Same disgusting result.
> I'm guessing that several really fine "mist
>coats" of shellac or Deft would have to be sprayed, 
>until it creates a seal up over the silicone-permeated
>lacquer underneath. Then decal, then full wet
>topcoats. But I thought I'd ask y'all how you might
>handle this stumper.
> Thanks!
> T
>
>
>
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