I'm going to go ahead and agree with Zat here in saying it probably isn't the best course of action but I'll offer some practical wisdom on the subject as well.
The only expandable foam I have any experience with is called Great Stuff and that experience is only in household applications.
It makes an air tight seal and is moisture resistant. Best of all, it only takes half an hour to set up to the point that you can start carving.
I'm not sure about Touch n Foam Max, though... It looks like it's basically the same product. I do see that it's made "green" which I guess is a selling point but that also seems to be driving the price up a couple dollars for the same volume. I'm seeing about eight dollars for Great Stuff verses nearly eleven for the same volume (20 oz) of Touch n Foam Max. I imagine the non-Max version of Touch n Foam is a little cheaper, though.
Do a test piece, regardless. Also, wear clothes you don't care about.
If expandable foam gets on anything you own, it becomes trash very quickly.
There's no getting that stuff out. It's even hard to get it off your skin.