[pianotech] U1 - stained bass strings

[James Grebe]

It looks like the strings on a Yammy gr a customer used alcohol to remove 
magic marker that his son put on the strings.  Almost like plating came off
James
James Grebe Est. 1962
Piano Tuner-Technician
Creator of Custom Caster Cups
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----- Original Message ----- 
From: "Rob Mitchell" <tpa2sfr at pacbell.net>
To: <pianotech at ptg.org>
Sent: Monday, October 19, 2009 1:31 PM
Subject: [pianotech] U1 - stained bass strings


> I've been working with Yamaha on this, but the best we've come up with is
> that some sort of atmospheric contaminant is attacking the strings. 
> Thought
> I would try this group to see if anyone has seen the problem. This is on a 
> 4
> year old Yamaha U1.
>
>
>
> As you can (hopefully) see from the pictures, this is a very unusual
> phenomena.  It looks to be some kind of ink or marker in some very odd
> places.  It occurs on ALL the wound bass strings under the damper felts 
> and
> at the hammer strike points.  For the damper felts, the stain is exactly 
> at
> the contact point between the felts and strings.  For the monochords, the
> stain wraps around the string.  For the bi-chords, the stain is between 
> the
> strings from the wedge.  It's as if someone used ink-soaked dampers and
> hammers to check for damper contact and strike point.  (The hammers and
> dampers themselves on this piano are normal and show no signs of the 
> stain).
> The stain is not just on the surface of the coils -- it seems to be all 
> the
> way into the grooves.
>
>
>
> Furthermore, both the L and R strings on B1 (as well as some other 
> strings)
> have the markings smeared from the dampers almost up to the tuning pins.
> And there is an every-fourth-string marking again closer to the tuning 
> pins.
> All the strings look completely normal and free of the markings below the
> dampers.  I tried some fine emery paper on a B1 string and the marks 
> seemed
> to scrape off fairly easily.  I didn't want to try anything more 
> aggressive
> like alcohol, wire brushing or steel wool.
>
>
>
> The customer's concern is that at a minimum, this diminishes the resale
> value of her piano and at worst, might be something that would accelerate
> string wear/breakage.
>
>
>
> Anyone seen this before?
>
>
>
> Rob
>
>
>
> Mitchell Piano Service
>
> (415) 994-1030
>
> www.mitchellpianoservice.com <http://www.mitchellpianoservice.com/>
>
>
>
>