Ultrasonic and pneumatic nebulizers for mist consolidation

Julie Dennin Ream <julieream [at] comcast__net> writes

>From time to time I am asked to advise colleagues on the purchase of
>equipment for use in mist consolidation projects. ...
>
>...  I would be interested in a
>dialogue surrounding the equipment conservators have chosen and how
>it has impacted their experiences in treatment. There are more and
>more devices on the medical market now--are the more expensive ones
>really worth it?  Please respond to the list.

We purchased a Maymed Aquilon nebulizer about a year ago in order to
consolidate some friable/cracking ink drawings. (Code S MAY 8460,
from Mayo Healthcare Pty Ltd; $AU380 incl. 10% GST. See
<URL:http://www.mayohealthcare.com.au/index.html>).

Specifications are as follows, in case they are of use:

    Voltage:                240VAC, 50Hz
    Power absorbed:         60 watts
    Max Pressure:           >350kpa
    Flow:                   >15Lpm
    Dynamic pressure:       >180kpa
    Flow:                   @8Lpm
    Weight:                 3kg

The Aquilon is marketed as being appropriate for heavy duty use and
for multiple users. (Its real use is for patients suffering from
cystic fibrosis etc). I had a chat with a sales representative and
after explaining the type of things we wanted to use it for, she
thought that the heavy duty motor would be the most appropriate -
i.e. to use with our slightly viscous solutions and for extended
periods. We had a play with one before we bought it and it seemed to
work OK, using the medication holder that comes with the machine.
(This only holds 10mls of solution; but I found that after that runs
out it's time for a break anyway).

I guess if considering a cheaper model you would need to consider
the power of the motor, and whether it is appropriate for the
viscosity and molecule size of your planned consolidant and the
length of time you plan to use it for -  I think nebulizers don't
cope so well with substances composed of larger molecules, but I'm
not sure about this.

I've used our nebulizer with weak solutions of methyl cellulose and
with 0.5% gelatin which both worked fine; the treatment of the
drawings was successful at any rate. My impression is that the mist
generated is not quite as fine as that generated by an ultrasonic
set-up (which I think is expected); also it comes out at some
velocity, unlike an ultrasonic mist which seems more gentle, so I
held the nozzle further away from the surface than you might
ordinarily.

I did have to fiddle around (i.e. retrofit) with different
widths/lengths of tubing etc to get a good flow--there was a
tendency for the consolidant to condense inside the tube before it
got out the other end if the tube was too narrow or long, and I
still had to watch out for drips. I set up a little clamp/stand to
keep the medication holder upright, and tried different ways of
making the end of the tube finer. Someone cleverer than me would be
able to retrofit the system in a much neater and more permanent
manner, but it did work. It still seemed easier to manage than the
ultrasonic set-up, but someone more familiar with this method than I
am might beg to differ.

I also think my 0.5% gelatin was becoming a bit thicker as the
treatment went on, but this was just a "feeling" and not based on
any real measurement. The machine's also a bit noisy, but not too
bad.

Re heating the consolidant, the solution in the container did feel a
bit warm after all that nebulizing, but my understanding is that the
temperature of any solvent or consolidant applied to a surface is
negated almost immediately by the temperature of the object itself
and the surrounding air. So I would imagine heating would only be of
benefit at the beginning, in order to make a consolidant less
viscous, or if you were somehow able to heat the whole shebang, e.g.
when items are consolidated inside a humidification chamber to aid
flow etc.

Alice Cannon
Paper Conservator
Conservation
State Library of Victoria
328 Swanston Street
Melbourne, Victoria 3000
+61 3 8664 7331
Fax: +61 3 9639 6559


                                  ***
                  Conservation DistList Instance 21:10
                  Distributed: Tuesday, June 12, 2007
                       Message Id: cdl-21-10-004
                                  ***