Hot Hide Glue
By Stephen Birkett, forwarded by Ron Yost
Hi all!
There's been a valuable thread running in the USENET group rec.music.makers.builders re: Hot Hide Glue. I'll summarize it below:
From: Stephen Birkett - sbirkett@uoguelph.ca
Stephen Birkett Fortepianos
Waterloo, Ontario, Canada
tel: 519-885-2228
fax: 519-763-4686
Quoting Stephen (edited to remove repeated material):
"The trouble with hide glue is that most people who use it think they still live in the 18th C. Employing a modern approach makes it just as convenient as synthetic glues, plus you get all the benefits: When used properly, hide glue is stronger than PVA's (Titebond), does not creep when cold like all PVA's can, and is no more susceptible to atmospheric moisture. For an instrument with 6000 kg of string force essentially held together with just the glue these are important properties. The glue also grabs very quickly, is very easy to clean up, and will accept stain, unlike all PVA's.
{ For the mixtures below, Stephen uses hide glue in the mid-300's gram
{ strength. He gets his glue from Lee Valley Tools. The following is a
{ clever method, IMHO - Ron
It isn't true that the glue has to be mixed fresh every day or so. You can mix up the glue in small plastic bottles... shampoo bottles are perfect. The trick is to use something airtight. As long as the water cannot evaporate it will stay in jelly form forever. To avoid spoilage problems keep it in the fridge between use.
{ I assume Stephen means to soak the glue crystals in cold water in
{ the plastic bottles, letting it 'swell up' as it absorbs the moisture,
{ just as is done in a glue pot? I further assume he soaks the glue
{ overnight before use (that's how I do it). - Ron
Do not heat the glue directly! Instead, use a 'double boiler' ... a crock pot on the low setting will keep a bath of water at 60C all day. When you need to use the glue float the plastic bottle for five minutes to heat the glue. Because the glue is airtight, the water will not evaporate and the glue will not get thick. You can just pour it out of the bottle! Keeping the glue hot all day will spoil it, so only heat when you need to use it.
You can slow the open time by mixing in urea. Basic glue has about 30 seconds open time... adding 10-percent (by weight) urea increases the open time to 2 minutes. 25-percent to 5 minutes, but it takes about 3 weeks to set up really hard. Urea WILL NOT weaken the final glue bond... only increase open time. You can mix up several different 'speeds' of glue in different plastic squeeze bottles... keep them all available. BTW: Franklin cold hide glue has so much urea in it that it never really cross-links to achieve a full set!!
{ This answers my earlier query as to whether Franklin cold hide glue
{ contained urea, and also means one should be able to concoct one's own
{ cold hide glue? BTW: As a result of the Trade Center and Oaklahoma
{ City bomb disasters, urea may be difficult to get in the U.S. I got
{ some at a garden center a couple years ago, but it may be unavailable
{ now?? - Ron
You don't actually need the urea for reasonably uncomplicated glue jobs. It's ESSENTIAL for large veneering though, where the extra open time of the 25-percent mixture comes in really handy!
It is not necessary to heat up the surfaces to be glued, except for really huge glue jobs like a piano soundboard. For really porous wood a quick glue size with thinned hot glue before the final glue job is a good trick.
The use of hot hide glue, like any professional tool or material, has to be learned, but once you learn it, it is amazing stuff. Its flexibility in open/setting times (depending on grade and mix) and its eternal reversibility make it the best for instrument use. It is NOT idiot-proof. You have to know what you're buying and how to use it."
--Close quote.
I'll keep an eye on the thread and post any interesting new material.
Ron Yost <ryost@fix.net> |
(Message sent Wed 5 Jun 1996, 03:50:03 GMT, from time zone GMT-0700.) |
|
|
Mechanical
Music Digest™ Archives
