Author Topic: Casting plaster rocks on a steep surface  (Read 819 times)

0 Members and 1 Guest are viewing this topic.

Bob

  • Crew
  • *
  • Posts: 433
  • Gender: Male
  • Respect: +545
Casting plaster rocks on a steep surface
« on: March 15, 2023, 05:02:51 PM »
0
I will shortly try my first large scale attempt at casting plaster rocks on to a styrofoam base.  The slope will be steep, so my question is whether the plaster will adhere sufficiently well, or should I put screws or nails into the styrofoam slope with the heads sticking out some to give the plaster something else to grab hold of?  I will eventually cast rocks to make Maryland Heights (see first page of my Cumberland Subdivision thread) and this will be both steep and large, and I don't want landslides to occur!  Anyone have experience with this?  Thanks!  Bob

wvgca

  • Crew
  • *
  • Posts: 320
  • Respect: +44
Re: Casting plaster rocks on a steep surface
« Reply #1 on: March 15, 2023, 05:18:26 PM »
0
best off letting the plaster get 3/4 hard, so that it will still somewhat conform to the surface .. i used this method on my layout eight years ago, and so far it's great

Scottl

  • Crew
  • *
  • Posts: 4792
  • Respect: +1362
Re: Casting plaster rocks on a steep surface
« Reply #2 on: March 15, 2023, 08:15:17 PM »
0
I purposely leave the styrofoam surface rough to help adhesion.  Nails or screws would work too but might be awkward with some molds.

CRL

  • Crew
  • *
  • Posts: 2329
  • Needs More Dirt.
  • Respect: +635
Re: Casting plaster rocks on a steep surface
« Reply #3 on: March 15, 2023, 10:47:42 PM »
+2
Do what the stucco guys do. Apply a scratch coat to the surface.

MetroRedLine

  • Crew
  • *
  • Posts: 580
  • Gender: Male
  • Respect: +170
    • Union Pacific Vallealmar Subdivision (Facebook Page)
Re: Casting plaster rocks on a steep surface
« Reply #4 on: March 19, 2023, 10:03:27 PM »
+4
Cast them outside the layout, then use adhesive caulk to glue them to your styrofoam scenery base. Use sculptamold to fill in any cracks/gaps. Paint everything over with a coating of artist's gesso, then stain/paint as desired.
Under the streets of Los Angeles