Re: Hard coating for foam toroid

[Esondrmn-at-xxxxxxx (by way of Terry Fritz <twftesla-at-xxxxxxxxxx>)]

In a message dated 11/7/00 6:40:40 PM Pacific Standard Time, tesla-at-pupman-dot-com 
writes:


> Original poster: "Lau, Gary" <Gary.Lau-at-compaq-dot-com> 
> 
> I recently placed an order for a custom 7" x 30" Styrofoam toroid from a
> place that makes custom plastic shapes, largely for theatrical props.  They
> have a completely computer-controlled milling operation and can make any
> complex shape.  They normally work with 2 lb Styrofoam, similar to what
> coffee cups are made of.  They could also order 3lb and 5lb foam.  The 5lb
> foam is similar to the stuff they make bicycle helmets out of - very tough
> stuff.  But the 3 and 5lb options added roughly $100-$200 to the total cost.
> I was concerned with the possibility of denting and wanted to make the
> toroid as dent-proof as possible, but at a reasonable cost.  
> 
> Initially I was told that they would be able to apply a very thick (1/8")
> coating of polyurethane.  I felt that such a coating on top of the 2lb foam
> ought to make it pretty dent resistant, so I choose that option.  After the
> foam was cut I learned that they would not be able to apply it as the cost
> would actually be very high.  So now I'm left with a foam toroid with little
> protection against dents.
> 
> What materials are there that I could coat it with to improve upon its
> dent-resistance?  I don't want to mess with fiberglass or anything that I
> would have to sand down.  I'm thinking self-leveling like epoxy.  Is this
> available at reasonable cost in bulk (quart)?  Is it thin enough that it
> could be poured on while the toroid is slowly rotated?  Is the cure time
> long enough that I can get the whole big thing coated before it starts
> curing?  Or are there other things?  Someone suggested the boating repair
> industry may have something I could use?
> 
> I will post pictures and details of cost, contacts, etc, to my web site
> after I receive and evaluate the toroid in the next couple of days.
> 
> Regards, Gary Lau
> Waltham, MA USA
> 
> 

Gary,

Good idea.  This sounds like a novel method to produce a large toroid.  I 
think you would want to be sure and test whatever coating you come up with on 
a sample piece of styrofoam.  I recall that many things act like a solvent 
and melt styrofoam.

Ed Sonderman