plaster scenery on foam?

[gregc]

my layout is built on a foam.   Since foam is flexible, I'm wonder how plaster scenery material can be attached to the foam without crumbling at the boundary?

I realize it could be hidden with foam scenery.   I wonder if there is something flexible that can stay firmly attached to both the foam base and plaster scenery?

thanks

[mlehman]

Greg,

I apply plaster rock castings using Sculptamold. It doesn't stay flexible, but they do remain stuck firmly to the foam. I use the rock castings to add detail to my overall application of Sculptamold as a base layer for scenery over foam.

FWIW, it seems like Sculptamold is a little pricey if purchased in the usual small sizes (locally ~$10 for 3 lbs.) But you can order 50 pound bags of the stuff form less than $100 -- and that covers a LOT of scenery. Sculptamold can also be textured and painted to represent various kinds of rock.

[RR_Mel]

I used Plaster of Paris over foam blocks to build maintains 28 years ago and its sill intact with no crumbling at all.  The guys on the forum talked me into Sculptamold a couple of yeas ago and it does very well over foam too. 

 

The only problems I’ve had is with Paper Mache, it shrinks as it dries and will pull foam in from the ends.  A 18” section of Paper Mache will shrink from ¾” to 1” in the drying process, bad news!  If the material under the Paper Mache doesn’t give the Paper Mache will crack.

 

I still occasionally use Paper Mache because it’s very light and much stronger than either Sculptamold or Plaster of Paris.  Paper Mache doesn’t crack if it’s applied correctly.  I cover the area with Saran Warp first then apply the Paper Mache, the Saran Wrap allows the Paper Mache to do its thing.  When the Paper Mache is totally dry (that can take a couple of days) I remove the Saran Wrap and glue the Paper Mache to the foam.

 

 

 

Mel

 

Modeling the early to mid 1950s SP in HO scale since 1951

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

[cowman]

I too used Sculptamold over foam and have had no problems in over 10 years.  I think the flexability of foam would only be a problem if you were moving a large piece often.  The 2" is quite stiff, even in a large sheet.  Even if you had a frequently moved module, they aren't usually too large and also need some sort of protection from "bump" damage like a piece of plywood, which will  help stiffen the module.

Good luck,

Richard

[MisterBeasley]

I've applied Gypsolite directly to foam and it seems to adhere pretty well.  More often, though, I use plaster cloth over scraps of foam to create a more uneven terrain.  The Gypsolite adheres very well to the plaster cloth.

[rrebell]

I use plaster cloth right over the foam, no problems. I put in a masonite facia and filled the crack with WS's Flexpaste.

[gregc]

appreciate all the comments.   feel motivated

[wvg_ca]

On my small layout, I used quite a bit of foam, all grades and elevations, and when I added terrain cloth sheets, instead of plaster I used diluted DAP caulking, when dry there was acceptable flex in the sheets, and over coats with thinned drywall premixied mud gave no signs of cracking or crumbling, good for around three years now..

I felt that using a slightly flexible mix on the cover sheets would also help reduce any possible 'drumming' sound normally seen with rigid plaster style coatings