Panel drying and finishing

[Fenton Murray]

Dave,
Applying  finish to one side will have a minor similarity to ribbing the 
panel with flat ribs. Allowing only the unfinished side to pick up moisture, 
or a least more moisture than the finished side, will allow that side to 
expand. The tensile strength of even the thinnest ribs far surpasses the 
strength required to hold one side of a panel stable as the other expands as 
in CC construction. I would think even veneer strips would be enough to 
crown a panel, maybe even masking tape. Not that I have any experience with 
CC construction, just off the wall commentary. As to your question of 
potential adverse affects of ribbing up a panel that was slightly unstable 
because of finish on one side and the uneven transfer of moisture, I 
wouldn't think the panel is going to care much once machine crowned ribs are 
glued up to create your rib crowned soundboard assembly. I have looked under 
many old pianos trying to see how they handled these types of chores. It 
seems I'm always seeing glue squeeze out, for that reason I rib up the 
panel, clean up the glue, then tape the sides and shoot it, looking 
underneath you will see a very small trace of the glue staining under the 
finish, this doesn't look bad as long as you don't use Titebond with it's 
ugly yellow color, great glue, but ugly.  The problem I've had here is 
having the possibility of a little bare wood exposed along the liner when 
looking underneath, for that reason I now favor a little extra finish for 
look's sake, this leaving perhaps a small amount of finished soundboard in 
the glue joint. I could probably be arrested for that, but I'll take my 
chances. Remember, my total experience is still under a half dozen boards.
Rhonda and I are going on a cruise next week, 5 days and 4 nights out of LA 
to Catalina and Ensenada. $200 each for everything, how can they do that? 
Who cares, I'd spend more than that at home, see ya.
Fenton
----- Original Message ----- 
From: "David Love" <davidlovepianos at comcast.net>
To: "'Pianotech List'" <pianotech at ptg.org>
Sent: Friday, October 24, 2008 3:01 PM
Subject: RE: Panel drying and finishing


> Presumably, then, if it did warp and you just left it in the hotbox longer
> it should straighten out once the moisture transfer had equalized through
> the panel?
>
> David Love
> davidlovepianos at comcast.net
> www.davidlovepianos.com
>
> -----Original Message-----
> From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On 
> Behalf
> Of Ron Nossaman
> Sent: Friday, October 24, 2008 2:41 PM
> To: Pianotech List
> Subject: Re: Panel drying and finishing
>
>
>
>> I have heard of some individuals who prefinish the side of the panel to 
>> be
>> ribbed first masking off the area that will be in contact with the inner
> rim
>> as well as the ribs.  I have not done this yet the idea of slightly 
>> easier
>> cleanup of glue without it soaking into the wood near the ribs is
> tempting.
>> However, I have found that when a piece of wood only has a finish on one
>> side and you change the EMC, it tends to warp.  First, why is that and
> does
>> that tendency suggest that the one side finishing process prior to 
>> ribbing
>> is a bad idea?
>>
>> David Love
>
> It does that because you've slowed the moisture transfer rate,
> thus the dimensional change rate, on the finished side. Is it
> a bad idea? I don't see why except for wasting more time and
> masking tape than if you just trimmed the squeeze out from the
> bare panel after it set up a bit. Different strokes.
> Ron N
>
>
>
>