One of the first things to consider in choosing woods to use in exhibit
cases is whether or not the wood is to be used in a sealed case or a
ventilated case.  Wood gives off corrosive acids and organic vapors which
can react with many materials.  In a case that is well ventilated, this is
not much of a problem.

However, if you are making a sealed case, special precautions should be
taken to protect any artifacts, to be sealed up with these vapors, inside
the case for a long period of time.

The least harmful solid woods to use in exhibit cases are:  poplar,
mahogany, walnut, basswood or balsa.
Woods to avoid are:  oak, yellow pine, teak, douglas fir, sweet chestnut,
red mahogany (Khaya), and cedar.

With plywoods and particleboards you not only need to be concerned with the
type of wood used but also with the type of adhesives used in their
manufacture.  If you must use plywood or particleboards select ones that are
made with phenol-formaldehyde adhesive.  Avoid the ones made with
urea-formaldehyde or melamine-formaldehyde because they will corrode metals
and alter the color of some pigments.

The least harmful plywoods are exterior grade or marine grade plywoods.  The
better particleboards are Medex or Medite II.   When you order these you
have to be real specific about what you want.  Many of the particleboards
look very much alike.  However, they are very different.  Medex is an
exterior grade while medite is made for interior use only.  Medex is better
to use because of the type of adhesive used while medite should be avoided
in exhibit cases.  To make things even more confusing, they came out with
what they call Medite II which is ok to use because it is made with a
special formaldehyde-free adhesive.  However, be sure that what you get is
Medite II and not medite.

Another concern with using wood is whether or not it is an endangered
species.   However, when properly stained, many woods can be made to match
more expensive species.

Also, whenever wood is used inside exhibit cases, it should be completely
sealed with either acrylic paint, water based urethane, or marvelseal.   The
important thing to remember here is that the word "sealed" does not mean the
same as just painted.   Sealed here means completely vapor tight, and
includes all the joints that may crack open later.

I hope this helps.
Earl Lock








-----Original Message-----
From: Whitney Watson <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Monday, November 13, 2000 4:34 PM
Subject: Appropriate case matls


>What is the current thinking on appropriate woods to use in creating an
>exhibit case.  The cases need to match in style and finish some old
>cases.  What are the issues with using walnut, mahogany, or ash?
>
>Thanks,
>
>Whitney
>
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