marton
I have a project to stock Cuba with old US pianos, and have met a
couple of comegen. Oxygen starvation using nitrogen or some other
inert gas seems best. The Getty Conservation inst. in LA says their
Ageless oxygen scavenger would be ineffectual at the volume of a
piano. Here is what I know so far. Keep me posted on your research.
blt
Comegen Eradication, Cuban Pianos
After reading reports from two Canadian museums and from the Getty
Conservation Institute's Shin Maekawa, it seems as though if you hate
comegen, oxygen-starvation is the way to go. Shin will be able to tell
us which gas method is better, carbon dioxide or nitrogen.
What, by the way, are comegen - those wood-eating Cuban pests -
scientifically or otherwise? I think they are what we call carpenter
ants. It's important to know the actual name when dealing with
researchers, to make sure we're all on the same bug before investing
lots of money.
The Canadian museums, before switching to carbon-dioxide, used to use
freezer-trucks, which are rented at $35/day in Canada. Articles
(mostly clothing) infested with what I think are clothes moths, were
left in -20û trucks for 7 days. (What would the effect be on comegen?
On piano soundboards? Would 7 days be enough? Are there such trucks
in Cuba, to use while we are setting up gas methods?)
The nitrogen method:
Make a bag of oygen-impermeable plastic big enough to contain an
upright piano, and another for a grand. The upright bag should be 67"
tall (height of tall upright + 7" dolly + a few inches for floor
padding), 67" long (to fit a very long upright) and 30" deep. The grand
bag, into which a piano on a spider-dolly could be rolled without
removing the legs and lyre, should be 50" tall, 67"wide, and 9'6" long
(in case of Imperial Grands). The bag is made of Filmpak 1193,
manufactured by Ludlow Laminating and Coating Division, Homer,
Louisiana 71040 tel.: (318)927-2531 and there are several distributors
in the U.S. It costs about $5./square meter. (Please, someone, do the
math for the cost of the square footage of Filmpak needed, and for the
bag's volume while you're at it.)
The bag is sealed at the edges with a tacking iron with heat control,
available from photo equipment stores for about $70. The bag is
reusable. (What is the best method for opening and sealing the front
door?) A heavy tarpaulin or a cloth-edged platform would protect the
floor of the bag from dolly wheels.
The bag is hung on a framework of PVC plastic pipe.
Obtain cylinder of nitrogen, liquid or gas (liquid is cheaper - Shin
guesses the cost/piano is about $12 - but I am not sure about the
effect on the environment in the bag of the coldness of the liquid
nitrogen - Shin says you have to guard against icing up of the fittings
with liquid). You need 8 times the volume of the bag to completely
flush the air and fill with nitrogen. Industrial grade high-pressure
nitrogen cylinders, 8,600 litres (size T or L) rent in the States for
$6/month and cost about $35 to fill. Liquid nitrogen, 160 liter (99,000
gaseous nitrogen liters) is $60 to fill and $30/month.
Between the bag and the cylinder you set up a gadget to humidify the
nitrogen - very important not to dry out the piano suddenly. It
consists of a jar of water, a dry jar, and a dry jar with an RH sensor,
into which the tubes from the cylinder go: one into the water to bubble
up wet nitrogen. The flows of each jar are regulated until what comes
out of the sensor jar and into the bag is about the same relative
humidity as the surrounding air. (I am not sure of the cost of this
simple set-up but I think it is under $200.)
The humidified nitrogen is introduced into the bag and the air
evacuated from the other side. Into the bag is introduced Ageless
Eyes, a Mitsubishi product, very cheap (Shin thinks Mitsubishi would
donate it if asked, apparently it has a short shelf-life and should not
be ordered in huge quantity) which is some kind of chemical indicator
that lets you know if the oxygen level goes above the critical .1%
level.
The tube-hole and evacuation hole in the bag are sealed and the piano
sits for 3-6 days. (Exact time seems possible to ascertain from Shin
once we know the real name of the comegen.)
The comegen become tremendously and permanently dead, and the piano is
checked again every few years.
The Carbon Dioxide method:
Same bag, (but does it have to be quite so impermeable?). Instead of
99% evacuation, oxygen only has to be 80% gone. (Should be cheaper,
therefore.)
Same PVC frame.
Carbon Dioxide cylinders cost about the same as nitrogen, but I would
guess you need much less per piano because of the less stringent
evacuation requirements.
Piano has to be left in 3 weeks.
Humidity is not so crucial, according to the Canadians.
All this considered, if the Cubans can get nitrogen, it seems to be
safe, cheap enough, quick, and more thorough than the carbon dioxide
method. If they cannot, a nitrogen generator costs $20,000, and may be
worth it.
The nitrogen set-up is portable, assuming the framework comes apart and
sets up easily. There is some question about the portability of the
carbon dioxide set-up.
I think the investment would be (now it would help if I had math
skills) $150 per bag, plus $75 per plastic framework, plus $350 for the
jars and fittings and miscellaneous unforseen stuff, so a 5-bag project
would cost about $1,500. If it costs another $15 per piano in
nitrogen, the total cost per piano would be $30 if you did 100
instruments. Less if you did more.
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