On Mon, 22 Mar 2010 04:29:13 -0700 (PDT), jmsiat
wrote:

I want to make a mould for a clear headlamp cover on a sports car.
The body is unpainted (right now) frp, If I could fill the 'socket"
in the front of the car with an expanding foam and work it into shape
after it hardens then I could get a positive, and then vacuum-mould a
bit of acrylic or polycarb to match. The fellow doing the body-work
and painting would like it very much if this did not ruin his nice
work. If there is not a non-sticky foam then what should I use as a
release agent - could be something as simple as parchment papaer I
suppose...

Is there a foam that would suit?

Any other suggestions welcome.

No, these covers are not otherwise available.

Go to a hobby shop and look for "Mountains in Minutes".
http://www.hobbymasters.com/islemoun...dscapekit.aspx

Model railroad buffs use it. It's a two-part foam that is a lot less
sticky than one-parts like Great Stuff, and it expands more. I'd use
PAM as a release agent on the car if you'll want to paint later,
because silicone release agents can be diffult to remove completely
and they do play hell with paint. PAM is basically lecithin, easily
removed with detergent.

Once the foam cures, it's non-sticky and easily shaped with sandpaper
or hot element (hot wire or soldering iron) though hot seriously
stinks so have good ventilation.

This stuff is also pretty good insulation. I measured the thermal
conductivity once, don't recall now but it was quite low.