refinishing problem

[bases-loaded@juno.com]

Hi Jim -

It's always the top of the lid where you have the most problems, eh!? 
Right where everyone can see it in all angles of light.  Never the bottom
side...

I think all of the suggestions have been good:  check your in-line
filters, adjust your spray pressure, try misting on several coats to
build up a surface you can top coat, perhaps a bit of retarder, etc...

Also, it sounds like you are battling fish-eye AND pinholing, which is a
double whammy.  Do you always have a fair amount of fish-eye to deal
with?  Have you never had pin-holing before?  How do you clean/prep the
surface before beginning the finishing schedule?

Another possible explanation could be that you are piling on the finish
too heavy AND having too much air flow across the surface.  In my
experience, this is yet another possible culprit for pin-holing.  It is
almost irresistable to spray the lid top a little too heavy, knowing the
kind of abuse and inspection it will receive, but it always works to your
disadvantage to do so, in my experience.

Lastly, to me it sounds as if you are really piling on the sealer coats. 
Is this SANDING sealer you are referring to?  IMHO 4 or more coats of
sanding sealer is way too much, and is inviting trouble.  If you are
wanting that much build, as in a pore-filled finish, I would think it
would be much more stable and less problematic to apply a paste wood
filler in the initial stages of refinishing.  This requires very little
sanding sealer to complete the build to a good flat surface.

What is also true, of course, and will forever be, is that things like
this can come and go in your shop like the wind, with no logical
explanation, and with no reoccurrence for years.  

Let's hope it is on its way out the door as we "speak"!

Mark Potter
bases-loaded@juno.com  

On Sat, 05 Aug 2000 16:30:03 -0500 jim krentzel <jim_shari@ruralnet1.com>
writes:
> List,
> I've refinished pianos for over 15 years, but a grand that I'm 
> working on
> now has me stumped.  The entire piano has refinished just fine with 
> the
> exception of the large lid.  After the second series of sealer 
> coats, the
> finish develops small bubbles.  The bubbles feel like bumps about 
> the size
> of a pin head, but after wet-sanding, they are small craters, so I 
> know they
> were actually bubbles in the finish.  After the first time this 
> happened, I
> stripped the lid again and started over.  I had the normal amount of
> fish-eye on the lid, but it went away after the first 4 coats of 
> sealer
> (with fish-eye eliminator) were wet-sanded flat.  Then after the 4th 
> added
> sealer coat, the bubbles appeared.  I'd appreciate any suggestions.
> Jim Krentzel
> 
> 
> 
>