Preemptive CA in bridges?

[Farrell]

"What would be wrong with preemptively treating all the bridge pins in the whole piano with CA..."

I'm not sure how much effect CA will have on a fully assembled newer piano in excellent condition - remember CA has little shear strength - but I think the general idea is a good one. This is why myself, and some others at least, epoxy-treat the bridge pin hole during the pinning procedure of rebuilding. There are different ways to do it, but I swab the bridge pin hole with a length of piano wire dipped in epoxy (I get a couple drops in there). Then I dip the base of the new bridge pin in epoxy and tap it in place.

Terry Farrell

----- Original Message ----- 
> Speaking of CA to fill the gaps around bridge pins, let me make a few 
> suppositions, then advance a thought.
> 
> 1. Besides filling the gap, the CA also penetrates the wood surrounding 
> the hole, and then solidifies into a sleeve which is custom-fit to the 
> pin and its particular hole. So, to the extent the CA adheres to the 
> pin, it not only corrects the fit, it also locks it into the bridge cap 
> and root.
> 
> 2. Presumably, the CA we choose to use is as rigid as wood or more so, 
> and therefore would conduct vibration as well or better (is this true?).
> 
> 3. Because it is a type of plastic, the CA'd bridge resists 
> humidity-cycle-related dimensional changes better than naked wood would.
> 
> 4. Therefore, besides filling gaps, it seems to me that CA _possibly_ 
> improves the bridge and cap functionally, above and beyond just 
> repairing looseness.
> 
> So this all makes me wonder: What would be wrong with preemptively 
> treating all the bridge pins in the whole piano with CA, before there is 
> ever a problem, to prevent the development of loose bridge pins and 
> related possible falseness, tuning instability, and ugly cracking? The 
> penetration of the glue into the surrounding wood spreads the 
> side-bearing load into a larger mass, thus reducing ovalling and 
> improving both dimensional and therefore tuning stability. The enhanced 
> stability might prevent cracking at the notches from ever getting 
> started, thus preserving both tone and appearance.
> 
> Has anyone noticed any kind of drawback to the use of CA, especially 
> tonal, or is its effect always somewhere between zero and positive?
> 
> Inquiringly,
> 
> -Mark Schecter
> Oakland, CA
> 
> 
> John Formsma wrote:
> >
> > What besides filling gaps would CA do? It wouldn't add mass.
> >
>
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