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Our company has made about ten stream tables over the years. For what  
it's worth, here are the materials we have tried:

1) Plasti-Grit. by far our favorite. (Available from Composition  
Materials (800) 262-7763. Be sure to ask for their stream table mix.)  
This material is chopped up recycled plastic. It does not get as  
smelly as organic material. Its low density means that oxbows,  
floodplains, deltas, etc. all form in a shorter length than with  
denser media that require a higher flow rate. The is what the Army  
Corps of Engineers uses in its big model of the Mississippi River.

2) Walnut shells, crushed corn cobs, etc. The big problem is that  
these organic materials get smelly over time. Their higher density  
seems to require a higher flow rate.

3) Crushed Garnet (variable sizes). This worked fairly well and did a  
good job approximating the surface of Mars for one exhibit. The big  
problem is that this material is highly abrasive. The wasn't a problem  
for the exhibit (which was solid stainless steel) but visitors walked  
away with small amounts on their hands which landed on other exhibits  
and wreaked havoc with the moving parts. In some of our designs we  
encourage visitors to rinse their hands by integrating a waterfall or  
fountain into the exhibit. But that wasn't possible with this design  
so we had to switch from the garnet.


Joe O'Connell
Creative Machines Inc.
3113 East Columbia Street
Tucson, AZ 85714
(520) 294-0939
(800) 861-7937
(520) 294-0848 fax

http://www.creativemachines.com
http://www.ballmachinesculptures.com








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