Gentlemen and Ladies,
I frankly don't care what "average' people would think of this
discussion. I'm fascinated and I am grateful for the knowledge and
views expressed. This kind of thing is why I have stayed with this
listserv after leaving the general lute listserv flame wars over a
year ago. And you all are expressing yourselves in polite terms and
not disparaging one another A rare pleasure in the world today.
Thank you all.
Tim
On Feb 6, 2009, at 8:15 PM, <[email protected]> wrote:
Hello All
A thread on hide glue?
Can we all imagine what "average" people must think of us debating
with such passions -
the benefits of hot animal parts?
Its wonderful...
I recommend of course , the lute courses by David Van Edwards . He
included therein a GREAT discourse on hide glue .
With regards to hide glue - its strength and resultant grading, I
had a most enlightening conversation once with
Eugene Thordahl, he of Bjorn Industries- who is widely regarded
as an expert in all such matters.
Yes he said, we grade and test all hide glue and indicate the
strength for the prospective client.
Hide glues are in fact sold in gram weights which correspond to the
tested strength of the product.
He recommended 180 gram for most all instrument building, and
perhaps for bridges a higher gram strength .
He also indicated that if one mixed 180 with 315 in equal
percentages one would get a gram strength roughly half way between
the two.
He also indicated that the higher the gram strength the lower the
working time. You really need to rehearse to use 315. There is
little if any time for errors to be
corrected by wiggling around the piece or you will introduce a weak
joint.
Also he told me that Hide glue is remarkably forgiving, has if
mixed a shortish shelf life even when kept in the fridge BUT an
indefinitely long shelf life if left in its native crystalline state.
At Bjorn he has done MANY comparative experiments testing strength
of joints with hide glues in which the glue has sat around, been
reheated etc and as well
been heated to 160f as opposed a more nominal 140f and that for
various lengths of time. You might consider giving Eugene a call on
these topics, he has both facts and figures..
After I complemented him on his enviable knowledge of the subject,
he replied ,dryly,
"Well Richard, when you've been around the glue pot as long as I
have, something is bound to stick....."
Yes rework is not just easier, its actually possible when using
hide glue.
I myself just finished restoring a sweet German Harp guitar by
Haberman for John Schneiderman out here on the west cost USA.
On that instrument someone actually tried to generate a repair
using the equivalent of Titebond.
It took me over a week of solid work to undo the mess where if
hide glue had been used it could have been done in less than 1/2
day. It is MORE than likely that the use of other glues as opposed
to hide glue could in fact make rework close to impossible. Imagine
replacing a worn fingerboard on a baroque guitar or 13 course lute
if it had been adhered with Titebond 3!!
.But there is another reason I prefer hide glue, and its one not
usually discussed.
Try to obtain or create as Keith Johnson of Reference Records did
in developing some loudspeakers some time ago, a tiny stethoscope.
He did this so he could listen to the smallest of sounds generated
in very specific places on a loudspeaker when excited with energy.
He listened to the spider, the surround in various places as well
as the cone itself near the center and outwards to the edges. As
well he listened to the sound of the "basket" the metal frame of
the speaker.
You would be amazed to know that the "sound" as generated by a
loudspeaker is not just what comes from the speakers cone itself,
but is an amalgam of all these sounds I have described as generated
by every part of the speaker one added to the other. It is
interesting to note that some of these contributed sounds were in
excess of 20percent pure distortion!.
The surrounds in particular are a problem with all dynamic
loudspeakers - as opposed to electrostatic types like the Quads.
This was the reason Keith did not like multiple arrays of small
long throw drivers - the distortion effects of the surrounds were
too distracting to him.
Like wise on a musical instrument, every part has its sonic
contribution to make.
In the guitar world there are those makers who can CLEARLY
distinguish between the sound a rosewood or ebony fingerboard
imparts to an instrument. Here the adhesives used will
unquestionably effect the sonic behavior of all the constituent
parts .
If the adhesive is too soft , creeps in any way , or is rubbery at
the joint - NO MATTER HOW STRONG - it will terminate the materials
involved in a manner equivalent to what one would expect in
using constrained layer damping. Constrained layer damping is used
to deaden resonance's - not transmit them. If the adhesive becomes
too brittle (and cyanoacrylate does this) NO MATTER HOW STRONG, it
will most likely act as a boundary and reflect back energy into the
materials involved on either side of the glue joint..
I don't believe we want these sorts of behaviors in our
instruments anywhere , as everything - neck fingerboard pegbox
staves etc as they are "connected" together with adhesive, act upon
one another and thereby contribute to the sonic behavior of the
instrument as a whole.
Now hide glue during MOST of its life transmits sound pretty darn
transparently .. This will couple the soundboard for instance
tightly to the braces, j bars etc as glued underneath over the
entire audio spectrum so that the top can develop a wonderful
resonant sound from PPP to FFF.
How many of us have noticed that upon first stringing up an
instrument in the white (and that JUST after the top and
fingerboard have been attached) , that on top of being a bit tight
sounding it can be also a bit dull as well and can be a little
out of balance too?.
Yet with only several days of time under its belt said instrument
begins to open up.. Usually we think that the "top is breaking in"
and while in my opinion I believe this is to be true I also believe
that a strong contributing factor in these first several days is
that the hide glue used in the last operations of building the
instrument -most likely in the adhering of the top to the bowl- is
becoming stiff enough to allow the transmission of the finer and
more subtle harmonics throughout the instrument. With the tops of
course an additional set of months is going to be required for the
instrument to really attain its bloom.
I believe that all the plans we use from these ancient genius'such
as Laux Mahler , Christian Hoffman , Tielke , etc and all their
bracing schemes and dimensions are BASED around the use of Hide
Glue with the knowledge gained over centuries as to its behavior.
None the less, I don't disagree with those who disdain its use.
After all Robert Lundberg sought to use (or so it would appear)
other glues whenever possible- but that we are now entering terra
incognita with respect to what such instruments are likely to do
sonically as a result....
Richard Lees
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