[pianotech] treating bridges with CA

[Al Guecia/AlliedPianoCraft]

Barbara, I also use a very thin epoxy (Rot Doctor is one example, there are 
others) which also works very well. I apply it with a small brush to the 
entire notched area and make sure it gets down into the cracks. It 
penetrates deep into the bridge and fortifies it from further damage.

Al


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From: "Barbara Richmond" <piano57 at comcast.net>
Sent: Monday, November 30, 2009 6:57 PM
To: "pianotech" <pianotech at ptg.org>
Subject: [pianotech] treating bridges with CA

> Greetings list,
>
> When I serviced a church's Yamaha C-6 (beyond warranty) for the first time 
> a few years ago, the lower treble section was wildly out of tune. I tuned 
> like crazy and was satisfied with how I left the piano. About six or seven 
> weeks later, I happened to get called to tune the same piano for a music 
> competition. I thought, "Ha, this is going to be a piece of cake." Ahem. 
> Though the same section wasn't as badly out of tune this time, I was 
> disappointed with what I found. Yes, there had been a change in season 
> (late fall to no-doubt-about-it winter), but still, the out-of-tuneness 
> wasn't the usual seasonal pattern. I had a look at the bridge; there were 
> cracks--not huge (yet). The church wasn't a regular account of mine, but I 
> mentioned to the person in charge that there was a problem that could get 
> worse. She was interested in my opinion and asked me to make an estimate. 
> I recommended CAing the bridge and installing a DC system. It's sort of a 
> long story (I won't go into it), but eventually the person in charge 
> started calling me to do the work there and I was asked to do something 
> about the bridge. Unfortunately, they opted out of the DC system.
>
> So, I arrived to CA the bridge. Even with the right applicator, CAing can 
> be tricky. I was very careful, but still, it's tight quarters working 
> around strings & bridge pins, and it's a challenge to keep CA glue from 
> contacting the strings. When a couple or more drops didn't go where they 
> were intended, I decided if I was going to sin, I'd sin boldly (thank you 
> Martin Luther). I thought about some key buttons that went through big 
> seasonal changes that I had treated with CA when I rebushed them. What an 
> improvement it made in reducing the swelling and shrinking (thank you, Dan 
> Tassin.) I also thought about Ed Foote telling about treating the wood 
> part of old Teflon parts with epoxy and what a difference it made in 
> reducing the clicks caused by seasonal changes. So, I decided to be bold 
> and apply the CA ever so slightly below the top surface of the bridge and 
> have it wick in and up to the bridge pin holes. Then I applied enough CA 
> so the remainder of the notching was all the same color. I was looking 
> forward to the next time I tuned the piano to see if my efforts would 
> improve the tuning stability in the section, but then there was one of 
> those political bru-ha-has at the church (one of the musicians didn't know 
> I was the person who had been working on the pianos, found out, and was 
> angry that he hadn't been consulted)--so I won't be back there on a 
> regular basis. Well, these things happen, but I'm mostly disappointed that 
> I can't track the results of my bet--work--experiment--whatever you want 
> to call it.
>
> Fast forward to today. I got called to come to another church and another 
> 7 foot piano (this time an 18 year old Kawai) that is developing those 
> little cracks in the treble bridge--not as bad as the Yamaha, but still a 
> concern. Here's my opportunity to give it another try. My aim/goal the 
> first time was to:
>
> 1 Keep further damage from occurring.
> 2 Help keep false beats at bay.
> 3 See if the treatment helps tuning stability.
>
> Has anyone else CA'd a bridge this way and had the opportunity to see the 
> results of your work? Comments?
>
> Thanks,
>
> Barbara Richmond, RPT
> near Peoria, Illinois
>
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