Large boulder ideas

[Jon Majors]

I'm wanting to make a large boulder for Wizard of Oz - something like 7' x 7' or so. I'm going to make a wooden frame using scraps and cover it with chicken wire, but what would you use for the top coat? I've heard people use portland cement, drywall compound, and a variety of other materials. I'd like it to be hard on the downstage side, and obviously paintable.

 

[DrewE]

One option--not necsssarily the best, just one that I've used for similar sorts of things--is plaster of paris and paper towels and/or cloth strips, kind of like paper mache. For the first layer, dip the cloth or whatever in the plaster and lay it on the framework. For successive layers, I find it easier to take a chip brush and brush on a splotch of plaster, then lay the paper or whatever in it, and then coat over the top with another brush stroke. About three or four layers are needed (in my experience) to keep the chicken wire pattern from showing through. It's a relatively hard and sturdy shell, but of course not suitable for weight bearing loads.

For coloring, one technique I saw demonstrated years ago--at a model railroad show, for railroad scenery, but it works elsewhere--is to mix some dry plaster and dry poster paint powder together, and then sprinkle it on using a sieve, and finally wet it down with a spray bottle of water. Layering various shades in this way can give a very organic looking result, with the water naturally causing the colorant to collect more in the low spots and valleys, etc.

 

[JohnD]

Also consider the use of a CB fave-VSSSD:

VSSSD

Van's Super Secret Scenic Dope.From this post: https://www.controlbooth.com/threads/the-chamber-of-secrets.4952/#post-53040*Vans Super Secret Scenic Dope*For those who don't know it's my favorit

www.controlbooth.com

 

[Jon Majors]

Also consider the use of a CB fave-VSSSD:

VSSSD

Van's Super Secret Scenic Dope.From this post: https://www.controlbooth.com/threads/the-chamber-of-secrets.4952/#post-53040*Vans Super Secret Scenic Dope*For those who don't know it's my favorit

www.controlbooth.com

Interesting - does this apply well to chicken wire or does it need a more solid base layer, like foam?

 

[Jon Majors]

One option--not necsssarily the best, just one that I've used for similar sorts of things--is plaster of paris and paper towels and/or cloth strips, kind of like paper mache. For the first layer, dip the cloth or whatever in the plaster and lay it on the framework. For successive layers, I find it easier to take a chip brush and brush on a splotch of plaster, then lay the paper or whatever in it, and then coat over the top with another brush stroke. About three or four layers are needed (in my experience) to keep the chicken wire pattern from showing through. It's a relatively hard and sturdy shell, but of course not suitable for weight bearing loads.

For coloring, one technique I saw demonstrated years ago--at a model railroad show, for railroad scenery, but it works elsewhere--is to mix some dry plaster and dry poster paint powder together, and then sprinkle it on using a sieve, and finally wet it down with a spray bottle of water. Layering various shades in this way can give a very organic looking result, with the water naturally causing the colorant to collect more in the low spots and valleys, etc.

It will not be weight-bearing at all.

 

[Van]

Interesting - does this apply well to chicken wire or does it need a more solid base layer, like foam?

Jon, VSSSD works well as a texture. it is NOT structural. If you want a boulder that people can sit or stand on nothing is going to work applied over chicken wire except, maybe fiberglass, several layers of it. If you want structural you will want to slice up the boulder, just like a slicer for 3d printing, and build it in layers or make vertical ribs with blocking or lathing in between. you could then wrap the boulder with muslin or cheese cloth, then use VSSSD on top of that to create final texture and color. Below is a shot of the edge of a platform for "The Flying Dutchman" -Sarasota Opera <can't remember the designer>these were intended to look like sheet ice so were, mostly, flat on top. they are made from a layer of 3/4" ply, 8" layer of bead foam, another layer of 3/4ply, then cheese cloth. the VSSSD was applied in and extremely thin gray layer the top coat painted for effect.

Another great way to construct is to build a shell out of 3/4" or 1/2" ply cut like pattern pieces, scab/tack it all together like assembling a 3d pattern, then build appropriate framing. fill gaps at seams with foam, add wads of glued up newsprint for random perturbances, cover it all in gauze then go crazy with the scenic dope.

Hope some of that helps. Boulders and rocky sets can be difficult without having flat walking, sitting standing surfaces designed into them .

 

[Jon Majors]

Jon, VSSSD works well as a texture. it is NOT structural. If you want a boulder that people can sit or stand on nothing is going to work applied over chicken wire except, maybe fiberglass, several layers of it. If you want structural you will want to slice up the boulder, just like a slicer for 3d printing, and build it in layers or make vertical ribs with blocking or lathing in between. you could then wrap the boulder with muslin or cheese cloth, then use VSSSD on top of that to create final texture and color. Below is a shot of the edge of a platform for "The Flying Dutchman" -Sarasota Opera <can't remember the designer>these were intended to look like sheet ice so were, mostly, flat on top. they are made from a layer of 3/4" ply, 8" layer of bead foam, another layer of 3/4ply, then cheese cloth. the VSSSD was applied in and extremely thin gray layer the top coat painted for effect.

Another great way to construct is to build a shell out of 3/4" or 1/2" ply cut like pattern pieces, scab/tack it all together like assembling a 3d pattern, then build appropriate framing. fill gaps at seams with foam, add wads of glued up newsprint for random perturbances, cover it all in gauze then go crazy with the scenic dope.

Hope some of that helps. Boulders and rocky sets can be difficult without having flat walking, sitting standing surfaces designed into them .

My rock doesn't need to be structural at all. Just a decorative setup that is large and looks like a rock

 

[Van]

My rock doesn't need to be structural at all. Just a decorative setup that is large and looks like a rock

Oops, missed that part. I should read to comprehend more...Yeah, in that case I'd do Chicken wire and newsprint papier mache' then add VSSSD on top for added texture and resilience.

 

[Jon Majors]

Oops, missed that part. I should read to comprehend more...Yeah, in that case I'd do Chicken wire and newsprint papier mache' then add VSSSD on top for added texture and resilience.

Great - I'll have to give it a try!

 

[Crisp image]

My rock doesn't need to be structural at all. Just a decorative setup that is large and looks like a rock

Until the director says "Wouldn't it be good to have actors stand on that rock. Can you make it happen?" Needless to say I have been there.