[CAUT] glues, Poletti

[Tim Coates]

I was an advocate of hide glues until people on this list suggested 
trying Trim and Molding glue for hammer installation and key bushings.  
I tried it and that's all I use for those situations now.  Joints are 
easily undone with heat, but hold tight even through extreme climate 
changes.  A small amount will hold the joint nicely, though I like to 
use the application methods with a collar and such.

Tim Coates
University of South Dakota
University of Sioux Falls


On Nov 29, 2007, at 2:09 AM, Diane Hofstetter wrote:

>  I'm interested in the question of glues, because I recently watched 
> an unsighted technician gluing grand hammers on with Titebond.  Most 
> of his glue joints were starved for glue and none had glue collars.  I 
> always used hot  hide glue, which I found easy to use, made great glue 
> collars and gave a nice, straight job.  But I can see where that is 
> impractical for this tech, so have been wondering what I might suggest 
> to him in the way of a better glue and better method. Ted, you 
> mentioned fish glue for key bushings, do you think it would be 
> appropriate for hammers?  Does anyone have any good ideas?
>  Thanks!
>  Diane
>
> Diane Hofstetter
>
> > From: edward.sambell at sympatico.ca
> > To: caut at ptg.org
> > Date: Wed, 28 Nov 2007 15:15:06 -0500
> > Subject: Re: [CAUT] glues, Poletti
> >
> > I read somewhere that all glues will creep to a greater or lesser 
> degree.
> > When I was teaching at George Brown College, it was impractical to 
> have a
> > large number of glue pots for hammer gluing, much as I would have 
> preferred
> > hide glue, so we used Titebond. It was much harder to extract 
> hammers from
> > the shanks with this than those glued with hide glue, though ten 
> minutes
> > with a heat gun let them be pulled off readily.The soundboard splits 
> we
> > commonly encounter in old pianos are mostly not true splits at all, 
> but are
> > separated joins, thus showing that creep has occured by shearing at 
> the
> > ribs. It can be assumed that most of these soundbards were glued 
> with hide
> > glue. It is just as well. as if the joints hold, there would be true 
> splits,
> > which would be very difficult to shim unless the grain is very 
> straight. I
> > enjoy working with hide glue, but it is more demanding. It must be 
> carefully
> > controlled in viscosity, though this is also an asset; large work 
> such as
> > cabinetry (and soundboards) should be heated, clamps prepared ahead 
> of
> > assembly and applied very quickly.I have taken to using fish glue 
> for key
> > re-bushing;, but found it necessary to prime coat the mortices first 
> with a
> > 50-50% dilute with water. It is slow setting, but will take hold 
> quickly.
> > Fish glue is easily reversible with the usual mix of warm water and 
> a little
> > wallpaper remover. It is availabele from Veritas. There is a small 
> bottle
> > with a brush in the lid which is ideal for light field repairs, and 
> refill
> > 17oz. bottles. I have seen failures with hide glue through lack of
> > understanding. One new grand I saw had a large number of loose 
> hammerheads.
> > The glue collars were all near black, indicating the glue had been 
> boiled.
> > Hide glue must not be heated above 150F. 140F to 145F is considered 
> the
> > proper range. Bill Spurlock recommends the use of a Rival Express 
> Hot Pot
> > and setting its temperature with the aid of a candy thermometer. I 
> saw these
> > recently in Wal-Mart, and think it a great idea. They cost around $15
> > compared to $100 or so for a dedicated glue pot.
> >
> > Ted Sambell
> > ----- Original Message -----
> > From: "Richard Brekne" <ricb at pianostemmer.no>
> > To: <pianotech at ptg.org>; <caut at ptg.org>
> > Sent: Wednesday, November 28, 2007 2:40 AM
> > Subject: [CAUT] glues, Poletti
> >
> >
> > > Hi Anne
> > >
> > > Creep in conditions like you mention seem quite easy to 
> understand. There
> > > is a kind of shear stress on a hitch pin rail that is glued to a
> > > soundboard. But there is another point from his site I found very
> > > disturbing . The assertion that Titebond and similar glues never 
> really
> > > harden and impart (to some degree) kind of damping effect, 
> absorbing some
> > > of the vibration energy instead of either reflecting or 
> transmitting. This
> > > has immediate implications for modern piano building as well as 
> older
> > > instruments. I'm not so sure how much a problem Creep is in 
> situations
> > > where there is not immediate and significant levels of shear 
> stress on the
> > > glue. But I'd like very much to hear more in depth comments about 
> all this
> > > in general.
> > >
> > > I'm not sure I'd have a problem using Titebond to fix a broken 
> shank out
> > > on some field repair job. But thats not really what I was talking 
> about.
> > > When in a restoration shop one has a variety of choices at hand.
> > >
> > > Cheers
> > > RicB
> > >
> > >
> > > Ric wrote:
> > >
> > > Hi Folks
> > >
> > > Reading in one of Anne Ackers i found a reference to the website
> > > of one
> > > Paul Poletti who has a side dedicated to glue. Please look over the
> > > following and provide comment.
> > >
> > > Thanks
> > > RicB
> > > ******************************
> > >
> > >
> > >
> > > He's absolutely right. Most harpsichords built with aliphatic 
> glues in
> > > the 1970's and 1980's demonstrate cold creep very nicely with the
> > > shrinking of the gap as the soundboard creeps forward, e.g.
> > >
> > > Besides, hide glue is so EASY to use. If it stinks, you're using 
> bad
> > > stuff.
> > >
> > > Anne
>
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