Please be very careful with the type of materials that you use in children's
interactives.

Many of the spray type foam insulation materials that can be purchased are
very hazardous to your health and should be handled with appropriate gloves
and respirators.   Make sure that you get a MSDS (Material Safety Data
Sheet) on the materials you are using and check for hazards when handling
the foams while it is  wet and after it cures.  And remember that the
exposure levels that are usually acceptable for adults are based on body
weight.

Children are very small and love to put things in their mouths.
Please be very careful.
Earl Lock


-----Original Message-----
From: Kyle McQuilkin <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Monday, July 16, 2001 9:07 AM
Subject: Re: fossil digs


James,

We've been working on some portable "digs" for the education department,
similar to your project, but on a much smaller scale.  For matrix, we have
been using a spray, foam insulation commonly used for insulating pipes and
wires.  It is inexpensive, and can be purchased at any hardware store.
Full cure takes about 24 hours, but it is easy to re-cover the "dig" after
it's been "dug."  The only drawbacks to this material are that it is very
soft and easy to remove, and that it only comes in white.  However, since
it is easy to dig, we don't need to combine sharp tools and small
children...it can be prepared with plastic tools.

Another option is to use dirt, plaster, vermiculite, or similar grainy
substrate loosely bonded with PVA (Vinac).  This mixture would be harder
than the above and would require metal tools for the excavation.  Varying
the ratio of PVA beads to acetone will mitigate the strength of the matrix.

I believe that the Dallas Museum of Natural History has a "dig" for a T rex
skull.  You might check and see what they use.

Regards,
Kyle









>I'm sorry if this has been covered, if there is an archive I should check
>please point me in the direction.
>
>We are redoing one of our galleries and one of the things they want to have
>is a mastodon dig.  I"ve already spoken with several people who have them
in
>their museums and got some very helpful hints.  What I am looking for is
>suggestions for the matrix to bury the fossil panel in.
>
>I've been told about wax and sand, but that seems a difficult thing to mix
>up.  Another recipe sounded pretty good, but I was warned that it creates
an
>enormus amount of dust.  We looked into recycled tires, stuff called boing,
>that they could just push out of the way.
>
>Has anyone a good recipe for making the matrix?  Maybe even ideas for
making
>it in different colored layers.  Any suggestions would be appreciated and
>thanks in advance for your help.
>
>James Crawford
>Preparator
>Rochester Museum & Science Center
>[log in to unmask]
>
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Kyle McQuilkin
Preparator
Paleontology Division
Museum of Texas Tech

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If you decide to leave Museum-L, please send a one line e-mail message to [log in to unmask] . The body of the message should read "Signoff Museum-L" (without the quotes).