Lovely work George :-) Not the only one here to learn about CNC for scenery and signage then:-)

Literally just been looking at foam coatings, and log in here to find the very subject come up ,coincidence is a strange thing...

Jesmonite is one of the big brands in this area;

http://www.jesmonite.com

Rosco Foamcoat is another big name

http://www.rosco.com/uk/scenic/foamcoat.cfm

Interested if you have had any chance to compare them with Hardkote anytime, George?

Then there is the U.S. variants , rubberised looks useful ;-)

http://www.sculpt.com/catalog_98/pow...e.htm#foamcoat

http://www.fxsupply.com/materials/foamcoat.html

After a chat with a prop maker a while back , he suggested looking at Venetian Plastering and Stucco....a watch of youtube might spark some ideas...

His experience was that using ordinary plaster with large amounts of PVA, building adhesive, in mix was pretty much functional as Jesmonite at ,er, substantially lower cost.

Haven`t yet had the chance to experiment, but the couple of things to change in the mix are the type of plaster, things like Hydrocal can be very hard and Venentian plaster mixes can contain marble dust and other fillers changing the properties.

PVA is strong and cheap , number of foam coats mention polyurethanes, water soluble polyurethane resins aren`t cheap but as varnishes have outstanding wear properties.

For long lasting outdoor use, guessing moving into cement rather than plaster based coatings.

Pulhamite was cement based with added ceramic, ground up pottery rejects, sure the Pulham Brothers would have been using polystyrene as a base if had been available at time:

http://pulham.org.uk/

http://www.english-heritage.org.uk/p...mite-rockwork/

The ultimate artificial statue stone was probably Coade Stone:

http://en.wikipedia.org/wiki/Coade_stone

Cheers
Adam

lighting tech and artificial water fall enthusiast