hide glue "tradition"

[David ilvedson]

> From:          Stephen Birkett <birketts@wright.aps.uoguelph.ca>
> Subject:       Re: hide glue "tradition"
> To:            pianotech@ptg.org
> Date:          Tue, 19 Aug 1997 02:23:28 -0500 (EDT)
> Reply-to:      pianotech@ptg.org

I size my key bushings before rebushing.  Would you also size 
hammers and shanks before hanging them?

David ilvedson, RPT
Pacifica, CA


> > Please elaborate - how DID the old guys do it???
> > 
> Three things:
> 1. Tooth all glued surfaces
> 2. Size everything
> 3. Use ultra-thin glue. Make thin glue, thin it until it looks like it 
> wouldn't glue anything, then add more water. Then it's thin enough.
> 
> Why?
> Toothing improves the bond and allows the extra glue somewhere to go when 
> you clamp the joint. Thin glue is very easy to expel from the joint and 
> requires less clamping pressue consequently. (After all that's why we 
> clamp.) Old toothing planes are lurking everywhere...they weren't just 
> used on veneers. In any case you only have to look to see toothed 
> surfaces everywhere.
> 
> Sizing prepares the wood and makes it behave. Unsized wood will suck out 
> the water from the glue almost as soon as you put it on, thus requiring 
> pre-heating as a last-ditch effort to make things last long enough to get 
> the clamps on. Thin glue can only be used on sized surfaces. Evidence for 
> sizing is clear on almost any old artifact, piano, organ, furniture etc.
> Sizing was often done en masse. The old organ builders sized more wood 
> than a railway trestle bridge needs.
> 
> Evidence for thin glue is clear on old pianos...you can see the long thin 
> runs that have been expelled from the joints. Glue that is the thickness 
> we are "supposed to" use nowadays does not flow in this manner. The runs 
> are so precise and long that you can even use them to analyse how a piano 
> case like a Graf was assembled.
> 
> By the way there is such a thing as "bad" glue...and there seems to be a 
> lot of it floating about on this continent. Take care. Also never heat 
> hide glue over 60C or it is impaired (see Wolfenden on hide glue)...in 
> fact any temp. below 60C that the glue is liquid is acceptable. The old 
> guys didn't use thermometers.
> 
> You can't tell by looking at broken down pianos whether the surfaces were
> pre-heated. But there is clear visible evidence for the above three
> points. And experience shows that the method works with no heating. 
> Heating every piee to glue is a royal pain in the butt, so you can bet the
> old guys would not have pre-heated. They weren't stupid. 
> 
> [No claim to having discovered the method above...credit is due to my 
> colleague Bill Jurgensen, an ex-patriot US organ, harpischord, piano, 
> violin maker who lives in Germany. Evidence on organ cases and pipes is 
> even more obvious than in pianos. There isn't much harder to glue than a 
> windchest on a cathedral organ...no pre-heat needed.]
> 
> Stephen
> 
> Stephen Birkett Fortepianos
> Authentic Reproductions of 18th and 19th Century Pianos
> 464 Winchester Drive
> Waterloo, Ontario
> Canada N2T 1K5
> tel: 519-885-2228
> email: birketts@wright.aps.uoguelph.ca
> 
> 
>