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PACIN Archived ListServ
Conversations VAPOR BARRIER
Question
from: From: Mark Ryan <mryan@plainsart.org>
Subject: vapor barrier question
Good morning,
I have a quick question regarding vapor barriers. We
are in the process of constructing two crates that will house prints that are
part of a traveling exhibition. What sort of material is commonly used for a vapor
barrier? Should we use Tyvek to line the interior of the crate? Each piece of
art will be wrapped in polyethylene and laid flat in a handling tray that fits
inside each crate. If we use Tyvek or a similar material, how is the Tyvek attached
to the interior of the crate? We would like to attach Ethafoam plank bumpers on
each side and bottom of the crate for the trays to cradle down into. Does the
Ethafoam attach well to the Tyvek, or should the planks be attached first, then
the Tyvek attached afterward?
Thank you in advance for any advice you
can offer in regards to this question and for all the advice offered in the past.
Sincerely,
Mark Ryan
Registrar
Reply from: Geoff
Browne <gbrowne@terrydowd.com>
Mark -
We and many others
no longer line crates with water or vapor barriers, but build the crate shells
using MDO (Medium Density Overlay) plywood, sealing joints with Dow 737 non-corrosive
silicone, and gasketing the crate with self-adhesive neoprene. In submerged tests,
the crates were watertight for up to 8 hours without painted exteriors, and with
painted exteriors were watertight for over 2 weeks.
If you are unfamiliar
with MDO, it was originally produced for use as exterior sign board (highway signs),
and differs from exterior plywood in that it has a phenolic plastic layer with
a Kraft overlay. While there is single faced MDO, we use MDO "2 sides".
Regarding chemistry - we were informed about MDO by a client / artisan, who has
built architectural miniatures since the '50s in sealed MDO cases, most with raw
metal castings of sculptures, etc., without any discoloration, tarnishing, etc.
despite being sealed in these cases for years - an Oddy test taken to the extreme.
When I asked the Canadian COnservation Institute their opinion of MDO, their comment
was that they routinely sealed objects in display cases made of MDO...
MDO
currently costs about 14% more than exterior AC plywood, but is well worth it
in terms of labor saved, and the fact that packing foam can be easily and securely
hot glued directly to crate walls. We use 3M 3792-LM-Q glue sticks, a low melt
that doesn't melt Ethafoam as easily as hotter glue sticks.
Geoff Browne
Senior
Project Manager
Terry Dowd, Inc.
gbrowne@terrydowd.com
From:
jlucas@artechseattle.com <jlucas@artechseattle.com>
RE: vapor barrier
question
1 option - glue the tyvec to the wood during the construction
of the crates
- then hot glue the ethafoam into place.
From:
Stephen Fixx <Stephen.Fixx@oberlin.edu>
RE: vapor barrier question
Dear Mr. Ryan,
We just received a dozen beautiful crates from Cornell
University that use the aforementioned MDO, use a neoprene gasket sealed lid,
are painted on the outside, and are lined on the inside with Marvel Seal! They
house a private collection of surrealist drawings that has been traveling around
for some time. No individual vapor barriers were used.
Best of luck, Stephen
F. Fixx
Assistant Exhibit Preparator
Oberlin College
Allen Memorial
Art Museum
87 N. Main St.
Oberlin, OH 44074-1161
440/775-6201; Fax: 440/775-6841
email:
stephen.fixx@oberlin.edu
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