Restorer, repairer, accessory-after-the-fact, serial
strangler?
You're not really happy with your old flute's
performance and so send it to someone for attention. The
technician fixes a few obviously leaking cracks, replaces a few
desiccated pads, replaces a crumbling stopper, and tightens up the
rocking thread wrapping on the tenons. Yesterday, we might have
called this person a restorer, but can we now? From now on, don't
we expect a restorer to be alarmed at finding rocking thread wrapping?
Wouldn't we expect them to do a few quick measurements to ascertain the
level of bore compression that might have set in, and to discuss this
with the owner, proposing whatever action seems appropriate to firstly
reverse the damage, then to avoid it reoccurring. Isn't that what
we mean by restoration - the act of returning an item to its original
condition? With the aim of keeping it there?
Would we be happy for a "repairer" to replace or augment
the thread on our loose flute without checking for damage? What is
a repairer, by comparison to a restorer? A technician who can
carry out routine repairs, but without the full understandings,
techniques and resources of the restorer? Wouldn't we hope they
would at least alert us that there might be an issue, rather than just
paper over the cracks and tell us nothing?
How would we, in future, regard a technician who whips
off the old loose wrapping and replaces it with something neater and
fuller? Perhaps, to keep up the strangulation metaphor, an
"accessory after the fact" might be the most generous reading we could
make. The technician didn't carry out the original strangulation,
but is not alerting authorities and is covering up the evidence.
But it's probably worse than that, isn't it. By replacing the
loosened weakened thread with fresh and tightened new material, hasn't
the technician become the next in a line of serial stranglers?
What are the questions?
Now it's easy, of course, sitting here in my ivory
tower, pointing the finger at hard-working flute restorers and
repairers, and demanding more of them. (Um, Ivory Tower?
Well, there are a few small chunks of ivory about, mostly attached to
the ends of flutes. And we are upstairs...)
But it's only fair that I provide some answers as well.
I'll do my best to help us all come to grips with this new issue.
Some of the questions that come to mind are:
-
How do we measure compression?
-
What's a quick check for existence of bore
compression
-
What might the original bores have looked like?
-
What are our options for restoring bore compression?
-
What are the effects of bore compression on tuning?
-
What level of shrinkage are we seeing in old flutes?
-
What are the effects of this shrinkage on tuning?
-
What level of bore compression isn't an issue for
the flute?
I'll be attempting to answer all these questions and
more in this series. You might have other questions you'd like
answered. Feel free to raise them with me.
Measuring compression
I should mention that
measuring compression is not altogether straightforward. Most
people measuring flutes, e.g. when preparing to make copies, use the
regular Telescoping or T-gauge, in conjunction with the micrometer. Set the
T-gauge to say 18mm, and see how far down the bore it will go.
Then move on to 17.8mm, repeat etc. But, as you can see from the
graphs, once you pass the constriction, you need to start opening up the
gauge again, not just go on to the next place it stops.
Follow the yellow Strangled
Boxwood curve in the graph reproduced below. Once you get down to 16.3mm, it
skims along from 10 to 15mm, and then won't stop until somewhere near
the middle of the section! That's a dead giveaway that something
is wrong. Obviously, it won't be so noticeable on flutes with mild
compression, but you'll still notice a bigger step than normal.
Follow the brown Camp trace, and note that there's only about a 10mm
step across the cavity. But you can still detect and map that.
So, the golden rule has to
be, when you find a step that's noticeably bigger than any other step, it needs
full investigation, not glossing over. Open your T-gauge a step,
introduce it on an angle to duck under the low overhang, straighten it
up and note how far in it will go and how far back it will come.
Keep increasing the setting until you've mapped the whole chamber.
A quick check for strangling.
This quick check for bore compression need only take a
few seconds. If, of course, it comes up positive, the restorer
might feel obliged to go on to map the damage and report to the
customer.
Set the T-gauge to the size of the opening at the top
tenon. Nip the clamp up just enough to stop it opening up when
removed. Now push the gauge down the bore. You should feel
resistance as the decreasing taper forces the gauge further closed.
If there is no compression, you will continue to feel that resistance
until you run out of handle.
If there is significant compression, you will suddenly
feel no resistance, as the gauge head traverses the chamber formed after
the compression.
You can use a similar test for bottom tenons. Once
set to the ID at the bottom of a section, it should be free to insert
further. If you detect resistance before you detect freedom, then
there is compression.
(Note that museums don't endorse this way of using
T-gauges. They reason that, if over centuries, many researchers
cram many T-gauges down the bores of the same flutes, measurable wear
will occur. In the outside world, a flute will be lucky if it's
measured twice in its lifetime, so that concern is unwarranted. So, in the museum environment,
always use the mapping
approach detailed further up.)
A note on T-gauges
T-gauges are one of those simple products that cost rather a
lot more than you expect. But it is worth getting good ones - the
cheap ones tend to be unreliable in action. If you have the
opportunity to buy them individually, do so - unless you also work on
bassoons you won't find much use for the larger sizes. I only use
three (max opening):
A message to museums?
What implications does our investigation have for those
museums with large and significant flute collections, with many of their
earlier flutes still sporting thread wrapping? Aren't they slowly
strangling their exhibits?
I suspect in most cases, probably not. The
instruments are probably being held in stable conditions, free from
extremes of heat, moisture and dryness. If the threads have been
on there for years, they have probably already done what damage they
can, while the flutes were out-and-about. But, if they have
thought for any reason to have flutes rethreaded recently (perhaps
because their collection is a "playing" one), they might well want to
reconsider their decisions.
Museums where flutes in the collection are not regularly
played will probably wish to retain their thread wrapping as a
significant part of the artefact.
We've been here before....
I encounter a sudden stab of déjà vu. Some years
back, I proposed publically that wood shrinkage over metal liners
was the mechanism that caused the exceedingly common splits in heads and
barrels, while unlined sections of flutes went unaffected. I think
that is universally accepted now, but there was outrage at the time, as
a look through the archives of the various Internet forums will confirm.
All sorts of bizarre counter-claims were made, e.g. that expansion of
the slide due to sudden changes in temperature was to blame. Since then,
other repairers and restorers have taken up my process of removing
the slide, fixing the crack, re-reaming the bore and reinstalling the
slide, as opposed to the previous bodge of attempting to screw or stitch
the crack closed against the irresistible forces of nature.
In a few years time, flute strangulation will be as
accepted as liner-induced splitting is today. Repairers and
restorers will be alert for signs of it, and will have adopted, adapted
or developed their own techniques for alleviating it. Not only
will we not remember what the fuss was about, we won't even remember the
fuss. Flutes will yield a collective sigh of relief.
Conclusion
I'll look forward to answering more of the questions
facing restorers in future editions. |