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Subject: Air pencil system

Air pencil system

From: Ted Stanley <tedstan>
Date: Monday, January 31, 2000
Cathy Atwood <atwooc [at] sosmail__state__mo__us> writes

>Ted Stanley's article on "A Tool for Pressure Sensitive Tape
>Removal: The AirPencil" appeared in Volume 17 of the Book and Paper
>Group Annual.  The tool he used for tape removal was the
>Zephyrtronics AirPencil ZT-2.

I thank Ms. Atwood for noting in her AirPencil communication that
Zephyrtronics has another model air pencil, but I would like to
clarify a few of her comments.

I called David Jacks, president of Zeophyrtronics, and I received
the following information.  Her reference to Zeophyrtronics making a
modified version of the air pencil for conservators is not quite
correct.  They already have a model known as the ZT-2-MIL, which
they have produced for the past several years.  They sell the units
exclusively to Motorola to fit their specific aerospace needs.

After the company received several calls from Ms. Atwood and other
conservators who read my article on the ZT-2, Zephyrtronics informed
them that there is a model with a different temperature calibration
that might useful as well for conservation.  At that point
Zephyrtronics decided to rename the ZT-2-MIL the ZT-2-ART for
conservation marketing purposes without changing its Motorola specs.
The company did not know that anyone was using their ZT-2 for
conservation before the calls came. The company's original purpose
for these units is for soldering electronic components. It's also my
impression from reading Ms. Atwood's communication that she seems to
state a lot of treatment performance characteristics about the
ZT-2-MIL without actually having used it (or the other model for
that matter).

Ms. Atwood also seems to infer that the temperature range on the
ZT-2 is 600-900 deg. F.  That's pretty dang hot!  Mr. Jacks said
that the temperature range is 400-650 deg. F at the nozzle or air
tip. Zephyrtronics states that the temperature range on the ZT-2-MIL
is 150 deg. F at 1" from the air tip with the airflow on highest max
setting and temperature on the lowest minimum as measured by a
temperature probe. And, the temperature is 218 deg. F at the same
distance with the airflow on max and the temperature on the highest
max setting.

I performed a test on the ZT-2 unit using the same settings and
distance. I recorded 128 deg. F at the max airflow/lowest
temperature setting with an air/gas temperature probe in midair and
151 deg. F with the probe against a flat surface, which is how one
would normally use the unit.  And, 185 deg. F at the max airflow/max
temperature setting with the probe in mid air and 225 deg. F with
the probe against a flat surface. The temperature read 111 deg. F at
2" from the surface and 99 deg. F at 2.5" from the surface using the
max airflow/lowest temperature setting. Depending on the adhesive
tape, I've found that for me a practical working range is between
2.5" to 3.5" or so using this setting. If indeed the ZT-2-MIL
settings are much lower than the temperatures that I have observed
on the ZT-2 then one would probably have to operate the unit at the
higher end of the temperature settings for it to perform
satisfactorily and safely. So it may boil down to six of one and
half a dozen of the other. But, in any event, burning or scorching
will occur with either unit if it is too close to the object.  So
one must be extremely careful in using these tools and should
perform a series of experiments before treating a collection object.
I mentioned this aspect in my article.

Mr. Jacks notes that the ZT-2-MIL has a 4 turn or revolution air
flow control valve or knob.  Where as the ZT-2 has a valve that
turns from a 7 o'clock position at the lowest setting to a 5 o'clock
position at the highest setting.  I've found that controlling the
airflow is an important factor in handling the unit.  On the face of
it I sort of prefer the ZT-2 set up because it's much easier to
reposition the airflow control knob to a particular setting if
someone else changes it.  It would save time and a lot of hair
pulling, which is especially important for those of us with not much
left on top. A new air tip is also offered.  Whether, it's effective
or not is another question.  I've experimented with all of my
different air tips and found that only one, the oval, works
particular well for various applications.  Other than the purported
lower temperature range and expanded airflow the units are virtually
the same in all other respects. Mr. Jacks did mention though that
the ceramic handle on the ZT-2-MIL heats ups quite a bit when the
unit operates at lower airflow settings.  That is not a problem with
the ZT-2.

I've had my unit for a couple of years and I'm very pleased with it.
I've used it for other types of treatment besides tape carrier
removal. But, I'm anxious to try the other model.  Mr. Jacks has
offered to recalibrate my unit to the ZT-2-MIL specs free of charge
to see how well it performs compared to its present calibration.
I'll have my unit recalibrated soon and I'll report what I've turned
up.  And, I would be happy to hear from others who may eventually
use this unit or have used similar units such as the British model.

My recent article in the Book & Paper Group Annual, Volume 17, A
Tool for Pressure Sensitive Tape Removal: The AirPencil, is not
meant to promote the Zephyrtronics AirPencil or any other air pencil
brand.  Its intent is to illuminate the potential of air pencil
technology for various applications in conservation.

Ted Stanley
Head, Special Collections Conservation Unit
& Paper Conservator
Preservation Office
Princeton University Library
One Washington Road
Princeton, NJ 08544-2098
Fax: 609-258-4105

                  Conservation DistList Instance 13:42
                Distributed: Wednesday, February 2, 2000
                       Message Id: cdl-13-42-010
Received on Monday, 31 January, 2000

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