Bird quill plectra, their performance and maintainance
This paper describes the mechanism of wear of bird quill in a harpsichord. The aim of the research was to test the
effectiveness of various methods the harpsichord technician uses
to treat the quills. Although only swan feathers were
systematically tested it is thought that the results will be
valid for many other feathers. In any event, the results given
here provide a useful guide until such time as testing of other
feathers has been undertaken. The primary aim of this paper is
to describe the testing and results, not to provide a succinct
guide to quill maintainance; this is offered at another
page on my website.
Introduction and summary of results
page updated 4 June 2012
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The touch with bird quills often suddenly becomes apparently
stiffer or "harder", making playing difficult and requiring some
intervention to restore normal performance. This feature is well
known among harpsichords using bird quill and has led some to
abandon their use in favour of Delrin plectra.
Testing of plectra made from swan feathers determined that the
apparent "hardening" is due to an increase in roughness, and
thereby increased friction, on the quill surface.
New wire strings were found to cause faster abrasion of quills
than those which have been played for some time, an effect which
has not been reported before.
A polishing procedure described by Tilman Skowroneck can usually
restore a usable plucking strength immediately and at any time
in the quill's life, albeit for a limited period.
The treatment methods which are effective or ineffective in
maintaining an even plucking strength are described here, based
on testing (begun in 2006) of oils and greases on both new and
used quills from swan feathers.
Some oils, when applied only to the top surface of the quill,
were found effective in maintaining a usable plucking strength
as the quill was abraded, providing they are used from the outset
with a new quill. Nevertheless, there was a noticeable variation
in strength of pluck as abrasion of the quill took place. Greases
(e.g. skin grease) were found to be less effective and olive oil
was ineffective. Synta-A-Lube (a watch oil) not only prevented
any increase in plucking strength but caused a decrease.
It was found that the most effective strategy is to apply oil
(Ballistol) only to the underside of the quill and allow it to
soak in for at least 45 minutes. Thereafter the quill showed no
wear, even in plucking a new, and presumably more abrasive,
string 2000 times, and no "hardening" during this period. This
oiling procedure also "restored" an already "hardened" quill to
the normal plucking strength. As far as I am aware, these effects
have not previously been reported.
The performance of bird quill plectra
Untreated bird quill used with new strings wears steadily, starting at the initial
voicing, even though its actual life may be several years.
Testing proceded by plucking a string 100 times, at about 120
beats per minute, then measuring the plucking strength with a
weight, before playing in further steps of 100. A calibrated weight
(of 15mm diameter brass rod, typically 115-120g) was used, the
position on the keylever being noted where the weight just causes
a pluck when lowered gently onto the key, with the string not
vibrating. For a lighter touch the voicing weight has to be moved
on the key, away from the player, a distance of being designated
hereinafter as "-x mm", e.g. 3 mm to 6 mm away from the player
= -3 to -6 mm. Although 3 mm might seem to be an insignificant
amount, it can make the difference in the 8> register on an upper
manual between a correct tonal balance with the lower manual <8,
and one which is a shade too "bright". A sensitive player will
also notice the difference in touch.
Quill is said not to "workharden" with use or age, which is one
of its useful characteristics compared with Delrin. Thus, the
nominal strength the voiced quill has been given will not
increase with use, as does Delrin. However as the quill tip
becomes polished with use the touch may become slightly lighter,
as was observed in testing, and on the lower manual of a
harpsichord after 5 months of use. There are also other phenomena
concerning changes in plucking strength which will be described
With a new, untreated quill plucking new strings you will usually
find that within 50-250 plucks the plectrum suddenly appears to
be much stiffer, equivalent to moving the voicing weight towards
the player by about 25-35 mm (designated hereinafter as "+x mm",
e.g. +25 to +35 mm). This increase in plucking strength may be
so large that the quill will not even pluck, and certainly the
plucking stagger in a 2-register instrument will have been
altered. This may also be accompanied by a "creaking" noise just
before plucking as the quill bends under the string. The sound
is much like opening a door, the hinge of which needs oiling.
However, a creaking noise is not always correlated with a high
As for the "creaking" noise: inspecting the tip of the plectrum
with a x3 jewellers' eyeglass shows that the string does not move
evenly towards the tip during the plucking operation, but jumps
in small discrete steps. This effect can be simulated in Delrin
plectra with horizontal scratches so it is thereby clear that
this is a mechanical problem with the quill.
At this stage, when the quill gives a higher plucking strength,
visual examination with a x3 jewellers' eyeglass might show a
slight matt area on the tip of the quill, but probably not a
groove. In any event, the surface has become slightly abraded and
apparently roughened (cf. Broekman, who correctly identifies the
cause). Microscopy would no doubt show this effect clearly. A
shallow groove will occur after considerable use, but does not
necessarily cause a high plucking strength.
Regarding the apparently increased stiffness: if the top surface
of the plectrum is cleaned x10 with a small antelope leather pad,
with the motion of wiping towards you, it will be found that the
quill will probably now be exactly at its original "strength"
again. Even wiping the quill with a clean fingertip has some
beneficial effect. A plausible explanation is that microscopic
flakes of quill material were removed from the surface, which
were causing additional friction. If you then operate this key
again x10-x30 you will probably find that the resistance has
again increased substantially, making playing of the key again
This increase in resistance is not the result of a defective
quill; it is the result of wear leading to a rough surface. No
doubt some quills might show more resistance than others.
Replacing the quill would not solve the problem; it would only
delay the next occurrence of such wear.
At this stage some people re-voice the plectrum in order to
restore the original plucking strength. However, repeated tests
have shown that this roughness can be a temporary phenomenon and
that the original plucking strength can often be restored
immediately by certain procedures, which will be described below.
The quill might even restore itself, if one could carry on
playing long enough (i.e. 400-700 plucks). However, the increased
stiffness I refer to is so excessive that a harpsichordist would
hardly wish to continue playing, thus I have not tested the
suggestion that the "stiffness" might correct itself.
From extensive, controlled tests I have conducted it has been
possible to determine the essential parameters in the wear of the
plectrum. Usually within the first 10-400 plucks abrasion of the
top surface of an untreated quill by a new string commences. By
1000 plucks a flat area is visible where the string makes contact
with the quill. With x30 magnification, the difference between
the orange-peel like surface of the quill and the flat area is
My tests have shown that once the surface of the quill starts to
break up it is usually possible to restore the normal strength
of pluck by "cleaning" the surface with a leather pad, or by
"polishing" the surface with the edge of your fingernail, while
supporting the quill on a voicing block. Tilman Skowroneck
described this fingernail-polishing procedure (p. 17), which is
one of the most significant techniques in quill maintainance, but
may not yet be widely known. Almost always a reduction in the
excessive plucking strength is possible with this method, and
often the original strength can be attained. In other cases the
strength returns to near the original position (i.e. with the
weight +3 mm to +8 mm towards the player).
After cleaning with leather the quill may become hard again
within about 30 plucks, but a fingernail-polished surface lasts
longer. This "polishing" might be explained as the more effective
removal of loose particles. Alternatively it might be explained
by the compaction or compression of the keratin material of which
the quill is composed. The actual effect remains to be
investigated at a microscopic level.
After a further few hundred plucks (c.800 in continuous testing)
the "polished" surface of an untreated quill breaks up again and
can yet again be restored with the fingernail. There may be no
limit to the number of times this cycle can be repeated, until
the plectrum is too weak for further use. It appears that during
the life of the untreated quill this breakup of the surface and
consequent sudden "hardening" can occur at any time.
However, the initial phase (up to 1000 plucks) seems be the more
difficult part of the quill's life. Tilman Skowroneck (p. 17)
writes of the first few months being difficult. Initially I
surmised that an external layer of the quill, perhaps of weaker
material, was being eroded, until a more resistant inner core was
reached. Thus, I thought that at this stage one might speak of
the "running in" being completed, to borrow from the old
automotive analogy, where piston rings were said to require
running in, i.e. contacting surfaces were smoothed. In later
testing it became apparent that it is the string itself which is
rough when new, but becomes polished with continued plucking, as
described below. This effect appears not to have been reported
What has been observed in these tests of an untreated top surface
is not an increase in stiffness or strength of the quill; it is
merely that more effort is required to overcome the surface
friction and thereby effect a pluck. For this reason it seems
technically correct to speak of an increase in plucking strength
although the cause is an increase in surface friction.
The harpsichord technician's task is to manage the breakup of the
quill structure in a controlled fashion so that, if possible, the
strength of pluck is neither weaker nor stronger.
A lubricant could be used to overcome the friction of the
excessive roughness, but this would also reduce the friction of
the quill on the string and tend to nullify one of the positive
characteristics of quills, namely that the player has more
control during the plucking and thus a better sense of touch than
with conventional Delrin plectra.
The application of a lubricating medium to the surface of a
"hardened" quill immediately reduces the friction, thereby giving
a reduced plucking strength. The lubricant holds the friction low
until such time as it has been worn off. A microcrystalline wax
(Cosmoloid) was found to wear off by 150 plucks although Klüber
Montagepaste 46 MR 401 was still effective after 500 plucks.
Synt-A-Lube, an expensive Swiss synthetic watch oil, was found
to prevent any increase in stiffness during the first 1000 plucks
and actually caused a decrease in plucking strength of -7 mm.
It is a common practice to oil plectra, but the use of grease
from one's own skin has also been recommended. My controlled
tests have shown that oil on the top surface of the quill manages
the initial abrasion of the quill-string interface better than
a grease, but also that oils vary in their effectiveness.
Friction-reducing lubrication is not the main effect of many oils
or skin grease, nor (I contend) the explanation of the benefit
which comes from using them.
Oil does not significantly penetrate the unworn upper surface of
a quill since it can be seen as a liquid on the surface even days
after application. It is not dispersed from the surface by 1000
plucks. Oil will penetrate the lower surface of the plectrum, and
has been observed to soak in entirely within two hours, at the
most. I therefore infer that oil will penetrate the top surface
slightly at the area where the string wears away the quill.
The few published sources on quill maintainance do not always
specify whether only the top surface of the quill (in contact
with the string), alternatively the lower surface, or both
surfaces should be oiled. Marc Vogel GmbH recommends the use of
their Kielöl (quill oil) on the top surface. The procedure Tilman
Skowroneck reports of soaking entire quills in olive oil
obviously implies oiling both surfaces. The following remarks
address the use of oil on the top surface.
Oiling the top surface
From the tests I have conducted I infer that oil applied to the
top surface does not "care for" the quill in contact with the
string, it probably does not soften it or "moisturise" it
significantly. In fact, as already noted, oil applied to the top
surface of an unused quill remains there for days and is
apparently not absorbed.
Most oils do not prevent the breakup of the quill structure; they
merely manage the abrasion in a controlled fashion. I think the
correct analogy is that of sanding a painted surface with
waterproof abrasive paper (so called "wet & dry" paper). If you
sand dry, then the paper quickly clogs with paint particles. If
you sand wet, then the particles are washed away from the sanding
area and do not clump together. This analogy would explain why
greases, (including Emu oil which has the viscosity nearer that
of a grease), perform slightly worse in this process. Thus, the
function of the oil is to aid the transport of abraded material
away from the immediate contact area, not to lubricate, i.e.
When oil is applied to a new quill there is typically a noticeable
increase in plucking strength within the first hundred plucks (+5
to +10 mm), but it may return to the original value after 400-700
plucks, depending on the type of oil. This seems to result from
the surface abrading, becoming rougher, then being smoothed by
further use. Undoubtedly the "hardening" effect is less
pronounced when oil is used and this creates a manageable touch
for the player, even though not a consistent one.
It has been said that when quills "harden", this is the time to
apply oil. This observation is correct as regards timing.
However, the inference that the quills have become "hard" and
require "softening" with oil would (based on my observations) be
incorrect. The "hardening" is evidence of the lack of controlled
removal of particles during abrasion at the quill's top surface
in contact with the string.
When oil is applied to a quill which has "run dry" and "hardened"
to say +25 mm, tests have shown that there might be a measurable,
immediate, and slight reduction (c. -8 mm) of plucking strength,
but this will depend on the type of oil. The better oils give the
least immediate effect. Even this slight reduction of friction
leaves the quill strength at +17 mm in this hypothetical, but
typical example. Playing is required in order to wear away the
offending particles; it may take 500 plucks for the original
plucking weight to be restored, although the improvement might
be to +8 mm after only 50 plucks. That is, after 50 plucks the
weight could be moved back 9 mm, so that the strength is now only
+8 mm compared with the original strength: +17 mm - 9 mm = +8 mm.
Marc Vogel GmbH's Kielöl [quill oil] and Klever's Ballistol (see
the Appendix for further details of oils and greases) were the
most satisfactory oils in maintaining a playable plucking
strength (i.e. an increase to +10 mm), although this obviously
involves a substantial variation from the original voicing
strength. Nevertheless these oils prevented a "hardening" of the
pluck to +25 to +35 mm as would occur without treatment.
Skin grease was found to be a little worse than these oils in
controlling the increase of plucking strength.
Olive oil was found ineffective in preventing "hardening" of the
plucking strength. This is an interesting finding considering
that it has the historical sanction of being recommended by
Adlung (see Martin Skowroneck, p.93 in German, p. 227 in
English). If olive oil is that which many harpsichordists have
used for oiling quills, it would help to explain the poor
reputation that quills have for an irregular touch.
An interesting exception was found in Synt-A-Lube, which
prevented any increase in plucking strength of a new quill, but
at the expense of reducing the plucking strength (as reported
above). Somewhat curiously, it failed to ameliorate a quill, the
plucking strength of which had already "hardened", which makes
it unsuitable for "repair" purposes.
The source of the wear in quills
In 2006 when I voiced a 3-register harpsichord with quills made
from swan feathers, I oiled the underside of the quills and gave
my customer a recommendation to do the same. She was pleasantly
surprised by the durability of the quills during the first year.
In 2010, when I had the opportunity again to use bird quill in
an instrument, I investigated in detail the apparently majority
opinion that the top surface of the quill should be oiled, with
the results reported above.
I then turned to an investigation of the oiling of the underside
of the plectra. This led in turn to a line of enquiry, which it
is convenient to report now.
After oiling the underside of the quill it appeared that this
method would considerably extend the period before wear of the
plectrum occurred. The question therefore arose, what would
happen if a quill were left untreated and played until it
"hardened", and only then oiled on the underside? This testing
brought about unexpected results.
Two untreated quills were therefore tested up to 2000 plucks,
with the surprising result that no increase in strength of pluck
occurred. One of these quills was further tested to a total of
3000 plucks. Visual examination showed absolutely no signs of
wear, whereas previous experience had shown obvious wear after
only 1000 plucks, and a "hardening" by about 700 plucks at the
On examination of the data it became evident that these untreated
quills plucked a string which had already been used for several
previous tests, i.e. for several thousand plucks. This gave rise
to the hypothesis that it is the string itself which had become
polished during the testing period and that this no longer
abraded the quill. If this hypothesis is correct then it implies
that we do not "run in" the quills, as I initially supposed
(mentioned above), but rather the strings.
In order to test this hypothesis I then used an untreated quill
on a new iron string with the result that the plectrum "hardened"
between 600 and 700 plucks by + 20 mm; wear was also obvious on
the top surface of the quill, just as previous testing had
showed. I therefore conclude that new strings are likely to cause
accelerated wear of quills, but that after a time the surface of
the string becomes polished and causes less damage to the quill.
This would explain Tilman Skowroneck's observation, that there
is an initial phase of difficulty, as reported above.
My observation about the abrading effect of new metal strings
appears not already to have been made in connection with quills,
but it is hardly surprising when one recalls the surface finish
of drawn metal strings, as shown by microscope photos. Thus, I
do not imply that it is a fault of the wire drawing process; the
surface imperfections are an inevitable consequence of wire
drawing. All systematic testing was undertaken with iron wire
strings (type A) made by Malcolm Rose.
I have not performed systematic tests using brass strings in
order to determine if they are less likely to cause rapid wear
of quills than iron strings. In any event I have observed
"hardening" of plectra with some brass strings. It probably
depends on the quality of surface finish of the material, which
in turn may depend upon the die itself. Thus, it might be found
that some gauges are more abrasive than others, depending on the
state of the die when the wire was drawn.
It would further follow, if my hypothesis about strings abrading
quills is correct, that replacement quills for already polished
strings should not show any signs of "hardening" or wear in the
early stages of their life, even if used without any oil.
Oiling the underside of the quill
It appears that oiling the underside of the quill, which oil then
penetrates the material, provides a reservoir of oil in the
quill, like a wick. One might ask whether this then "lubricates"
the top surface? Quills in the treble of 8' registers are often
only about 0.22 mm thick at the tip, so migration of oil from the
underside to the top is not improbable.
After two applications of Ballistol over five hours, which
achieved saturation of the quill, and before testing began, the
plucking strength was found to have increased significantly (+6
mm). After 700 plucks the plucking strength diminished by 2 mm,
and had returned to the original value after 1000 plucks.
It was found that it was not necessary to achieve saturation of
the quill in order for there to be a significant oiling effect
which "protects" the quill. When the quill was given a single,
liberal application of Ballistol on the underside, this was found
to have been absorbed within 45 minutes and produced an increase
in plucking strength of only 3 mm. A small watercolour brush (no.
2; e.g. da vinci synthetics series 303) may be used. An "oiler"
made from a small piece of wire, e.g. a paperclip, c. 0.8 mm
diameter, also picks up the right amount of oil for one quill.
The jack is then laid flat, with the quill pointing downwards.
After this period any excess oil can be removed with a cotton bud
or tissue paper.
Similar stiffening results were obtained with Kielöl and olive
oil applied and left for 45 minutes. Almond oil and Emu oil,
similarly applied, produced no change in plucking strength,
perhaps due to a larger molecular size.
My hypothesis to explain this stiffening effect is that the
interstital spaces in the quill had become filled with oil,
which, being effectively incompressible, had increased the
stiffness of the material. With playing, the excess oil appears
to have been mechanically expelled so that the original stiffness
is regained after 1000 plucks.
Testing of a new quill, which had been oiled on the underside
with Ballistol, on a new iron string showed that no "hardening"
had occurred after 2000 plucks. Thus, oiling the underside
appears to confer the ability to resist abrasion, even with a new
string, which is, from the evidence of the testing, apparently
rougher than a used one.
This is a remarkable contrast to the situation where oil is
applied to the top surface since there is typically an increase
in plucking strength during the first 500 plucks while the
surface of the quill is abraded.
The other notable effect of oiling the underside of the quill is
that after 2000 plucks there was no sign of wear on the tip of
the quill where it contacts the string, as was observed with a
x3 jewellers' eyeglass. This was surprising considering the
obvious wear observed with new strings when only the top of the
quill was oiled, or when the quill was left untreated. My tests
show that this occurs only when the underside of the quill is
It therefore appears that reduced wear of the quill can be expected and therefore a longer quill life.
As a result, it seems that the best procedure is to oil only the
underside: this confers the benefical protection and avoids any
effect of oil on the top surface reducing the player's "feel" of
the plucking action.
It has not been ascertained whether there are differences in the
performance of oils or greases when applied to the underside of
the quill which plucks a new iron string.
Restoring the original plucking strength through oiling the
Returning to the experiment of testing the effect of oiling the
underside of a quill which has become "hardened" through playing:
This same hardened quill was then liberally oiled with Ballistol
(see the list of oils below for further details) on the underside
and left for 45 minutes, after which period the under surface was
wiped dry of oil with a cotton bud. The plectrum was found to
have regained exactly its previous plucking strength.
Furthermore, this strength did not change during a further 200
plucks, indicating that the improvement is longer lasting than
merely polishing the quill.
This result is surprising considering that oiling the top surface
has relatively little effect in restoring the prior plucking
strength, as found during extensive testing reported above.
Furthermore, the improvements possible with oiling the top
surface were only gained after further playing. However, the
practical implications are that oiling the underside will
"restore" a quill to normal performance, albeit with a certain
delay (45 minutes) until the oil has sufficiently penetrated the
Why does oiling have an effect?
Although it is unnecessary for the harpsichord technician to know
why his methods work, it is nevertheless of interest to
understand the mechanism of oiling.
There are clearly different effects of oiling, depending on
whether one applies it to the top surface or the underside. I
have already suggested two explanations. In the case of oil
applied to the top surface it seems as if the dispersal of
abraded quill material is involved. When oil is applied to the
underside it is readily absorbed, so it must fill cavities in the
quill structure. For this reason I suggested that the oil being
incompressible created additional stiffness from being being
trapped in the cavities.
Why it should be that oiling the underside is so much more
effective in preventing abrasion of a quill, even with a new
wire, is not clear. Can it be that the oil being incompressible
supports the interstitial cavities against collapse? It would be
the task of further research to investigate this matter, probably
at the microscopic level.
It is also unclear what caused the temporary increase in
stiffness of a partly abraded quill when oiled on the top surface
and left to relax a few hours. Could it be that "flakes" of quill
material are caused to stand up by the partial absorption of oil,
which in turn create a rougher surface for the string? It is a
hypothesis which could be tested.
Requirements for oils
Two essential requirements for an oil, as applied to the
underside, would be a non-drying quality and long life since the
oil will be absorbed by the quill structure and presumably remain
there (at least in part) as long as the quill is in use.
Since Ballistol is considered to meet the requirements of non-
drying, long shelf life, and minimum deterioration in use, there
was no practical purpose for me in rigorous testing of less
Vogel's Kielöl and almond oil may in practice be equivalent to
Ballistol for oiling the underside, but I have not tested this.
I have found the shelf life of Kielöl is apparently longer than
stated (1 year). I have no reports that the three-register
harpsichord I quilled in 2006, which quills were oiled with
Kielöl on the underside, has given an unsatisfactory performance.
Almond oil is commonly classified as a "non-drying" oil. I can
confirm that almond oil does not show any tendency to "dry" even
after a month, when spread as a thin film, but after 5 months
exposure to the air the oil becomes noticeably more viscous and
For quills one preferably requires the assurance that an oil will
not harden after longer periods. The watch industry changed from
"natural" oils (e.g. neatsfoot oil, of animal origin) to
"synthetic" ones (paraffin based) in order to reduce the gumming
effects of oil over time. Frei reports that this changed the
maintainance period for watches from about 18 months to 5-7
years; good for the watches, but bad for the watch cleaning
These considerations on oils might appear overly cautious to the
harpsichordist, but for instruments which are used
professionally, the long-term use of unsuitable materials or
procedures will eventually cause higher maintainance costs.
The life of quills
I have not tested whether oiling the underside extends the life
of the plectrum, although the indications are that wear is significantly reduced by this procedure. It would be necessary to define what one
means by "life". Marc Vogel GmbH claims an "extended life" of the
quill through the use of their Kielöl, although their
recommendation is to oil the top surface. Tilman Skowroneck (p.
17-18) is sceptical that quills soaked in oil last longer.
It is apparent from the results I have reported that in order to
decide such an issue one would have to design the tests so as to
compare quills oiled on the top (or on the underside) with
untreated quills. Would one use a "brute force" playing method
which continued plucking an untreated or treated quill, even if
it showed "hardening"? Obviously, in the real harpsichord world
one would ensure, in one way or another, that the plucking
strength remained relatively constant. Presumably the "reference
quill", i.e. the one not oiled, would just be re-voiced when it
hardened and tested again "dry". However, this regime of use
could be said to provide an unrealistic and unnatural loading of
the quill. It is, therefore, not self-evident how one should
compare an untreated quill with a treated one. Furthermore, a
testing machine for this purpose would need to have the quill
pluck a string with a suitable force. It should also be able to
recognise the onset of "hardening" in order to then halt the
testing so that some intervention could take place. It would also
have to recognise when a quill had weakened substantially and
then halt the testing, since quills often fail by becoming weak
or developing a split. Would one use a new string for the test
or one which had been "run in"? If a number of quills were tested
in this fashion and the testing parameters were carefully
controlled it should be possible to produce results which reflect
the use of quills in a harpsichord and which are statistically
significant to a specified level of confidence. However, it will
be clear from this brief assessment that the testing required is
not a trivial undertaking in order for any statistically-significant results to be determined.
A "creaking" noise is an inevitable phenomenon of quills and
often increases just after oiling, possibly due to the
(hypothetical) "scales" standing up. I have only removed it
temporarily using lubricants, although it may sometimes be
lessened by oils or greases. Polishing with the root of a swan
feather was ineffective. It can be transitory and appears to
depend on large, local disturbances in the surface of the quill
structure. Presumably as the quill is worn away the "creaking"
may also disappear.
Other "stiffening" effects
Testing showed that an increase in plucking strength occurs
(typically +8 mm) with quills which have been oiled or greased
on the top surface and then left a few hours to "relax". This
phenomenon appears not to have been reported until now and
controlled testing with a weight is necessary to reveal it. After
10 plucks the extra strength is usually reduced to near the
previous value. Thus, one might speak of a "waking up" period,
when the quill quickly loses the additional "stiffness" on being
played a few times. The sensitive player will feel these
variations, but might never have measured them. Thus, the "real
world" situation for quills oiled on the top surface is probably
one of continuously-changing plucking strength, perhaps held
within a range of 8 mm (i.e. +/- 4 mm). This may be part of the
explanation for the reputation quills have for being variable in
A slight increase (c.+6 to +8 mm) in plucking strength also
occurs if one applies oil (or grease) to the top surface of a
quill which has been in continuous use. The fact that the
increase in plucking strength does not necessarily occur
immediately when oiled, but requires 10 plucks to develop the
additional "stiffness", suggests that the oil or grease has to
be absorbed by the quill. The experience of oiling the underside
of the plectra, which caused an increase in stiffness without
plucking having occurred, is perhaps evidence of a similar
mechanism of oil absorbtion.
Humidity and temperature effects
It is often reported that quill (e.g. turkey) is sensitive to
humidity and temperature. Tests I conducted in 2006 on a few
voiced swan quills showed no measurable change due to a large
increase in humidity over about 12 hours. Only one plectrum in
20 samples showed a change following a decrease of humidity (with
an attendant increase in temperature). These tests were conducted
on relatively unworn plectra, which were probably mostly
untreated with oil. Having discovered the stiffening effect which
occurs with quills that have been oiled on the top surface and
left to relax, there is yet another factor to consider. The
practical testing problem would be in separating effects due to
humidity change and those due to stiffening following relaxation
since it would be necessary to wait some time for humidity to
penetrate the quill and in this period the stiffening effect
could take place. It may be supposed that the stiffening effect
I have observed could have been attributed by others to
temperature or humidity effects. Only systematic testing along
the lines I have indicated here would show what the causes might
be. My testing has been conducted solely with swan quills, which
material was chosen following Martin Skowroneck's recommendation
of their durability (German p. 92; English p. 226). He also
recommends seagull heron and condor feathers (ibid.). Other
feathers apparently yield poorer results: turkey quills
reportedly give difficulty with high and low humidity.
I have not yet conducted any humidity and temperature tests on
plectra which were oiled on the underside, but no stiffening
effect following relaxation was noticed in a working instrument
over several weeks.
The primary findings are as follows:
1. The "hardening" effect in bird quill used as plectra is due
to roughness on the surface, leading to increased friction, thereby requiring more effort to effect a pluck. Only Broekman
appears to have reported this until now.
2. Abrasion of the surface of an untreated quill is rapid with
new strings, presumably being due to the microscopic surface
structure of the drawn wire. This finding has not been previously
3. Oiling the top surface of the quill with Kielöl (Vogel's quill
oil) or Ballistol, is only moderately effective in controlling
the abrasion produced by the string and thereby keeping changes
of plucking strength within a playable range. Skin grease is
worse than these oils. The traditional olive oil is a poor
performer in this respect. Only Synt-A-Lube was found to prevent
"hardening" of the touch.
4. An effective treatment for quills which both reduces abrasion
of the surface and restores the mechanical performance of abraded
quills is to soak the underside of the quill with a suitable oil.
This finding is believed to be new. Ballistol has been found
satisfactory for the purpose. At the time of writing a 3-register
instrument has experienced no "hardening" of any quills over a
period of 6 months indicating the success of the strategy.
Annie Kalifa's enthusiasm for the use of bird quill provided an
important impetus for this work. I am grateful to Tilman
Skowroneck for his exchanges with me on this subject. Mark Ransom
kindly provided comments on an earlier version of this text,
which have improved the focus. Nathalie Leuenberger has supported
this project with detailed observations of her bird-quilled
Hendrick Broekman, Hubbard Harpsichords. To Quill or Not to
Keith Hill. Plastic versus Organic. Some Thoughts on the Subject
of Quilling: Including a Method for Voicing Bird Quills
Martin Skowroneck. Cembalobau (Bochinsky, Bergkirchen, 2003), pp.
89-94 (in German), pp. 226-228 (in English).
Otto Frei. http://www.ofrei.com/page246.html
Tilman Skowroneck. Harpsichord Voicing:
Marc Vogel GmbH.
Oils and lubricants in comparison, used on the top surface of
The following comments relate to the treatment of only the top
surface of quills on a newly-strung instrument. They became less
relevent after the benefit of oiling the underside had been
established. However, this information may have some value for
those who have oiled the top surface and wish to understand the
effects of different oils. It also gives some indication of the
extent of my testing.
The reader is reminded that without any treatment a new quill
plucking a new string would probably show an increase in plucking
strength, measured with a voicing weight of +25 mm (nearer the
player), which is colloquially referred to as a "hardening" of
The tests performed using these oils were on new and used quills,
but some oils have been tested only once, although usually up to
1000 plucks. It would be necessary to test several quills with
each material in order to give a statistically-reliable,
quantitative description, i.e. how large the effect is. However,
the descriptions below are believed to be qualitatively correct,
i.e. in describing the type of performance involved.
Klever's "Ballistol" and Marc Vogel GmbH's "Kielöl" [= quill oil]
are both suitable for new quills and treating those which show
signs of "hardening", i.e. where the surface has become abraded
and is rough. On new quills with new strings the initial
roughness is often overcome with Ballistol or Kielöl after 400
plucks with an increase in plucking strength of +3 to +10 mm in
this period. On already "hardened" quills (i.e. c. +25 mm) these
oils produce an immediate improvement of about -10 to -15 mm, and
after c.150-300 plucks the voicing weight might be only +3 mm
from the original position. Kielöl might be the better of the two
oils for new plectra, but it might also be a slightly better
lubricant, which can be interpreted as a worse oil from the point
of view of touch. Further tests would be required to establish
if there is any significant difference between the two since the
characteristics of quill vary widely. No quill ever became "hard"
(i.e. + 25 mm) during testing when there was still Kielöl or
Ballistol on the top surface, although there was an increase in
Ballistol is mostly a paraffin oil of medicinal quality, and is
thus a "synthetic oil". It was originally formulated as an oil
for guns and the shelf life is said to be several decades. It is
relatively inexpensive (50ml currently costs € 2.67 + sales tax
from www.conrad.de). This oil thus represents the best value and
should have shelflife of several years, if not decades (according
to manufacturer's information).
Marc Vogel's Kielöl is stated to have a shelflife of c. 1 year.
The composition has not been disclosed but is stated (private
communication) to contain vegetable matter. 30ml currently costs
€ 8.70 + sales tax.
Olive oil (good quality, cold pressed, extra vergine) was found
to give a high initial plucking strength (+20) on new quill, +12
by x50 plucks, reduced to +6 by x400 plucks, thereafter returning
to +11 by 1000 plucks. It was ineffective on quills which were
already "hard". Even a quill which had already been plucked 2300
times ran "hard" while coated with olive oil, suggesting that its
usefulness is limited. Olive oil might also become sticky with
time and is therefore not to be recommended.
Moebius Synt-A-Lube 9010 is an expensive synthetic Swiss watch
oil, € 19.50 + sales tax for 2ml, with a stated shelflife of
6 years. It was the only oil tested which prevented "hardening"
of the touch (when used on the top surface). On one test it had the effect of lightening the
touch of new quill within the first 1000 plucks (-3 mm
immediately, -5 mm after 100 plucks, -7 mm after 700 plucks), so
it is obviously effective as a lubricant and therefore less
useful for quills when we would like our adjusted voicing to
remain as it is. Somewhat surprisingly, given this good
performance (and as with olive oil), Synt-A-Lube was ineffective
on abraded quills which were already "hard".
Klüber Montagepaste [assembly grease] 46 MR 401 is a white
synthetic grease, with a viscosity not much more than olive oil.
It has the effect of reducing a "hard" quill from +35 mm to only
+10 mm immediately and to +5 mm (or possibly to the original
value) after 10 plucks. After 500 plucks the quill was still
working normally. The disadvantage is that it removes some of the
"feel" of a quill plucking the string by reducing the friction.
It could find use where it is desired to restore the original
plucking strength quickly and with the minimum of work, for
example in an entire register of quills, which has uncertain and
variable performance and must be brought quickly to a playable
state. It has not yet been tested on new quills.
Skin grease has little immediate lubricating effect in reducing
the plucking strength of an already rough quill. On a new quill
a gradual increase in plucking strength up to +14 mm at 600-800
plucks was observed and by 1000 plucks the plucking strength was
still at +12 mm. Thus, skin grease has a relatively poor
performance when used on new quills for "running them in",
although it will keep them in a playable state. When the quill
has already been well used (i.e. after 1000 plucks), skin grease
was found to be effective in keeping one quill at its normal
strength over 1800 plucks (at which point the testing was
stopped). In retrospect it must be questioned whether the effect
was due to the grease or that the string had become polished by
this stage. These findings revise previously published opinions
about the effectiveness of skin grease.
Petroleum jelly (Vaseline) has a slight and immediate lubricating
effect (-10 mm) when used on a "hardened" quill, but the strength
of pluck was still +10 mm after 500 plucks so this material is
comparable with skin grease in effectiveness.
Emu oil has been described by Keith Hill. Although usually called
an oil, has the viscosity of a light grease (which may vary with
temperature). When used on a new quill it showed an immediate
increase in plucking strength (+11 mm), leading to a
significantly greater plucking strength (i.e. "hardening") of +22
mm after only 10 plucks, which was reduced to +2 mm by 400
plucks, but had not reached the original value until 600 plucks.
Thus, it appears to be worse than Kielöl or Ballistol, but may
be slightly more effective than skin grease. Since it is from the
emu bird it will, like other animal or vegetable oils,
deteriorate with time and may be subject to bacterial attack. It
is usually sold without a preservative and said to have a shelf
life (unopened) of 6 months to 3 years. Prices are around € 18
for 55ml (+ sales tax).