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Subject: Tyvek and Coroplast

Tyvek and Coroplast

From: Lisa Mibach <perygrine>
Date: Sunday, December 27, 1992
Tyvek is one of my favorite materials (right up there with Coroplast and
Archivart Abaca unbuffered tissue).  I first discovered it in 1980 as
cheap car covers when I was working for a museum in Canada.  It worked
great for our antique cars in dusty off-site storage, so I decided to
use it for threshing machines and fire engines and farm wagons. Needless
to say, I needed a somewhat larger size than the relatively svelte
Cadillac model.  Lacking a Mr. Big and Tall, I turned on my
conservator's Scrounging SuperSense, and realized that this was the
stuff of which disposable clothing is made.  A quick cruise through my
Government Purchasing Guide gave me the names of some dispo clothing
manufacturers, one of whom was perfectly happy to sell me garment weight
Tyvek at $.83 Canadian per meter (50" wide).  Now this was his resale
price, after shipping, customs fees, duty, and currency exchange, and he
was still making a profit!  A quick calculation showed this to be less
than half the cost of 3 mil polyethylene drop cloths on sale (and, she
sniffed, of (ahem) unknown ancestry), and a *lot* less than the 10 mil
poly we normally used for dust covers, and also less than unbleached
muslin.  Realizing that I was sitting on the museum equivalent of the
Manhattan project, I began scientific testing (hey, conservators are
supposed to be scientific, right?)

First test condition: the roof leaks on a long holiday.  Empirical
translation: I left a Tyvek 1422 cover on my bicycle outdoors for a
year, through 90F summers with thunderstorms, and -40F winters.  Water
pooled, but not until the second year did the water actually leak on my
bike (presumably, brought on by uv breakdown).  Test One completed
satisfactorily.  Note: potential for condensation moisture under draped
covers: better than polyethylene, because of Gore-tex-like permeability
to vapor diffusion; less good than muslin.

Test Two: Condition: You cruise the aisles peering through the
once-transparent polyethylene dust covers, and lift one to find out how
things are faring underneath, and the accumulated dust falls all over
you. Real-time equivalent experience: less translucent (but we don't
care, do we? we have perfect shelf lists.....), dust about the same.

Test Three: Getting the covers made.  Polyethylene requires the careful
attention of staff to rig combinations of shower hooks, Velcro, etc.
Tyvek can be sewn on a machine, so can be farmed out to the loving corps
of sewing volunteer ladies.  Score one for Tyvek.

Test Four: Cost.  Tyvek wins hands-down.  Note: at $.83 Can/meter in
1980, works out to about $.60 sq. yd.  (More now, but still not much).
By comparison, Critic's Choice varies from $1.40 for the heavier Tyvek
liner to $6.20 for the waterproof liner.  The non-woven fabric intended
as a soft wrapping (not that soft, either) is $3.30 sq. yd; Archivart
Abaca non-buffered tissue is $1.65 sq yd.

Test Five: Availability: 10 mil poly fairly easily available, with
unknown additives; muslin ditto, but needs washing and ironing, so add
laundry costs (I don't do laundry anymore).  Most regions have a dispo
clothing manufacturer to make union-mandated work clothing.  In the US,
information (and samples) are available from Clarence Lanier, DuPont
Packaging 800-334-0639.

Additives: most commercially available Tyvek has manufacturing additives
in the form of uv stabilizers (which I do not believe outgas), possibly
slip agents, as polyethylene sheeting does, and anti-stats, which are
noted in passing as a possible concern, although I do not have evidence
of resulting problems.  Tyvek for banners is Corona-treated
(electrostatic treatment) to accept printing inks.  One grade (I think
it's Type E, although I cannot check at the moment, since a dear
colleague made off with my spec sheets) is available with no additives
or treatments.  But I don't bother, since I don't enclose collections
permanently and in close contact with the Tyvek.  Dust covers seem to me
to have enough air exchange to minimize the problem, and we don't bother
with archival quality for polyethylene dust covers either.

Note that Critic's Choice plain liner is Tyvek, but Select liners and
non-woven fabric are NOMEX aramid, a fiber made principally for fire
protection clothing.  Parchment-like and expensive, it does not fill me
with enthusiasm, as it seems an expensive substitute for more useful
materials.  JB Freeman, Marketing Rep at Dupont, is anxious to find uses
for the material, but has heard only from art handlers, who are perhaps
less picky than conservators about materials.  Mr. Freeman is most
genial, and is happy to send samples.  He can be reached at

Thicknesses:  a wide range is available.  1073D, for example, is
paper-stiff, and is used for lab notebook pages (used by underwater
archaeologists to take notes underwater: accepts pencil and ink); this
also makes dandy museum labels; you can have it pre-printed and cut to
label size.  Mailing envelope weight is somewhat lighter.  These heavier
weights make useful temporary mending materials: in a pinch, US Post
Office Envelopes can be turned inside-out.....1422 is the standard
garment weight most useful for covers and non-abrasive temporary
wrappings; 1322(?) is the same weight, but micro-perforated, in case you
really worry about condensation.  It keeps liquid water off for a while
as well.  I am not at all sure that the draft-proofing housewrap is
useful: it is much thicker, and printed all over.

In short, I think Tyvek is about the greatest since sliced bread, and
would be happy to entertain discussion of pros and cons (no, it isn't
perfect, and not for everything: There Is No Panacea!)

It is important not to confuse Tyvek with Critic's choice, a product I
that is mostly redundant as far as I can see:  the Tyvek part is over
priced, and the soft wrap is abrasive and not as good as Abaca tissue;
the nylon liner can be done cheaper with MarvelSeal 1311
(polyethylene:foil laminate) available from Ludlow Pkg.  Besides, so
what if the liner is flame-resistant? the plywood crate isn't, and the
contents probably aren't.  Who are we kidding?  Gore tried to sell us
Gore-tex too, and it is useful as a humidifying felt, but we can make do
with much simpler materials.

Coroplast ....ahhhhhh! (smelling the sweet polyethylene: polypropylene
copolymer).  You've seen it: corrugated plastic: greenhouses, real
estate signs; trendy boxes and briefcases.  Inert (except for the Static
treatment for printing), cuts with knife, comes in 4x8 sheets in a
variety of colors, including white and translucent (makes nice humidity
chamber supports for polyethylene sheeting) at about $10-13 sheet.
Avail from shipping suppliers. Not flameproof, though can be bought
treated for same, but becomes expensive. But, our *collections* are not

Coroplast can be used to make dandy Solander boxes if you have a knack
for box patterns.  Just add a liner of acid free (or buffered if you
prefer) mat board as a humidity buffering liner. Cheap like borsht. Only
problems are: it does tend to flex at longer than 2-3 feet, and takes
adhesive poorly, so screw-together plastic or metal rivets are
suggested.  These is a way to make self rivets with a hot-melt glue gun,
but I'm not sure it's worth the trouble.

The post office boxes are Coroplast, though I prefer the blue,
straight-sided Canadian post office boxes more: they stack, and are just
the right width to carry, and are available in a variety of depths:
average $5 per box (shipped flat)..

For samples call Coroplast (800-666-2241) and ask for Quebec supplier of
Canadian blue boxes.  Or for sheets for cheap  do-it-yourself boxes:
Fome-Board Service Center 2211 N. Elston Ave Chicago IL 60614

Lisa Mibach

                  Conservation DistList Instance 6:34
                  Distributed: Sunday, January 3, 1993
                        Message Id: cdl-6-34-004
Received on Sunday, 27 December, 1992

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