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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?<BR>
Thanks!<BR>
Diane<BR><BR>Diane Hofstetter<BR><BR>> From: edward.sambell@sympatico.ca<BR>> To: caut@ptg.org<BR>> Date: Wed, 28 Nov 2007 15:15:06 -0500<BR>> Subject: Re: [CAUT] glues, Poletti<BR>> <BR>> I read somewhere that all glues will creep to a greater or lesser degree. <BR>> When I was teaching at George Brown College, it was impractical to have a <BR>> large number of glue pots for hammer gluing, much as I would have preferred <BR>> hide glue, so we used Titebond. It was much harder to extract hammers from <BR>> the shanks with this than those glued with hide glue, though ten minutes <BR>> with a heat gun let them be pulled off readily.The soundboard splits we <BR>> commonly encounter in old pianos are mostly not true splits at all, but are <BR>> separated joins, thus showing that creep has occured by shearing at the <BR>> ribs. It can be assumed that most of these soundbards were glued with hide <BR>> glue. It is just as well. as if the joints hold, there would be true splits, <BR>> which would be very difficult to shim unless the grain is very straight. I <BR>> enjoy working with hide glue, but it is more demanding. It must be carefully <BR>> controlled in viscosity, though this is also an asset; large work such as <BR>> cabinetry (and soundboards) should be heated, clamps prepared ahead of <BR>> assembly and applied very quickly.I have taken to using fish glue for key <BR>> re-bushing;, but found it necessary to prime coat the mortices first with a <BR>> 50-50% dilute with water. It is slow setting, but will take hold quickly. <BR>> Fish glue is easily reversible with the usual mix of warm water and a little <BR>> wallpaper remover. It is availabele from Veritas. There is a small bottle <BR>> with a brush in the lid which is ideal for light field repairs, and refill <BR>> 17oz. bottles. I have seen failures with hide glue through lack of <BR>> understanding. One new grand I saw had a large number of loose hammerheads. <BR>> The glue collars were all near black, indicating the glue had been boiled. <BR>> Hide glue must not be heated above 150F. 140F to 145F is considered the <BR>> proper range. Bill Spurlock recommends the use of a Rival Express Hot Pot <BR>> and setting its temperature with the aid of a candy thermometer. I saw these <BR>> recently in Wal-Mart, and think it a great idea. They cost around $15 <BR>> compared to $100 or so for a dedicated glue pot.<BR>> <BR>> Ted Sambell<BR>> ----- Original Message ----- <BR>> From: "Richard Brekne" <ricb@pianostemmer.no><BR>> To: <pianotech@ptg.org>; <caut@ptg.org><BR>> Sent: Wednesday, November 28, 2007 2:40 AM<BR>> Subject: [CAUT] glues, Poletti<BR>> <BR>> <BR>> > Hi Anne<BR>> ><BR>> > Creep in conditions like you mention seem quite easy to understand. There <BR>> > is a kind of shear stress on a hitch pin rail that is glued to a <BR>> > soundboard. But there is another point from his site I found very <BR>> > disturbing . The assertion that Titebond and similar glues never really <BR>> > harden and impart (to some degree) kind of damping effect, absorbing some <BR>> > of the vibration energy instead of either reflecting or transmitting. This <BR>> > has immediate implications for modern piano building as well as older <BR>> > instruments. I'm not so sure how much a problem Creep is in situations <BR>> > where there is not immediate and significant levels of shear stress on the <BR>> > glue. But I'd like very much to hear more in depth comments about all this <BR>> > in general.<BR>> ><BR>> > I'm not sure I'd have a problem using Titebond to fix a broken shank out <BR>> > on some field repair job. But thats not really what I was talking about. <BR>> > When in a restoration shop one has a variety of choices at hand.<BR>> ><BR>> > Cheers<BR>> > RicB<BR>> ><BR>> ><BR>> > Ric wrote:<BR>> ><BR>> > Hi Folks<BR>> ><BR>> > Reading in one of Anne Ackers i found a reference to the website<BR>> > of one<BR>> > Paul Poletti who has a side dedicated to glue. Please look over the<BR>> > following and provide comment.<BR>> ><BR>> > Thanks<BR>> > RicB<BR>> > ******************************<BR>> ><BR>> ><BR>> ><BR>> > He's absolutely right. Most harpsichords built with aliphatic glues in <BR>> > the 1970's and 1980's demonstrate cold creep very nicely with the <BR>> > shrinking of the gap as the soundboard creeps forward, e.g.<BR>> ><BR>> > Besides, hide glue is so EASY to use. If it stinks, you're using bad <BR>> > stuff.<BR>> ><BR>> > Anne <BR><BR></body>
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