Hard shell "fixer" for making props

curtis73

Well-Known Member
Not even sure what to call it.


I'll give a specific example of what I need. I'm building a rock. It is a scenic element for an upcoming show. It has to be large enough to seat two people, but light enough for one person to carry it offstage between scenes. I have the rocks formed. I basically carved them from extruded polystyrene (pink insulation panels) but they are covered with a mache' of burlap, canvas, and glue to make them look more rock-like and to prevent paint from sloughing off revealing pink foam underneath.


I need something I can spray (or brush) on that is a "fixer." When I say fixer, I don't mean like hairspray to give it a little stiffness, I mean like you can stand on it. I could mix up epoxy and coat the whole thing, but that gets expensive and messy fast.


I'm thinking like the plasticky stuff they spray over chicken wire to make dioramas at the Zoo or in the "pacific ocean" display at an Aquarium. Maybe an epoxy that is thin enough to spray. Hard shell stuff. In the future I want to get two part expanding foam so I can cast things like this, then I want to be able to spray [insert brilliant idea] over it to make it a hard, light, durable theater prop.


Does something like this exist?
 
Not even sure what to call it.


I'll give a specific example of what I need. I'm building a rock. It is a scenic element for an upcoming show. It has to be large enough to seat two people, but light enough for one person to carry it offstage between scenes. I have the rocks formed. I basically carved them from extruded polystyrene (pink insulation panels) but they are covered with a mache' of burlap, canvas, and glue to make them look more rock-like and to prevent paint from sloughing off revealing pink foam underneath.


I need something I can spray (or brush) on that is a "fixer." When I say fixer, I don't mean like hairspray to give it a little stiffness, I mean like you can stand on it. I could mix up epoxy and coat the whole thing, but that gets expensive and messy fast.


I'm thinking like the plasticky stuff they spray over chicken wire to make dioramas at the Zoo or in the "pacific ocean" display at an Aquarium. Maybe an epoxy that is thin enough to spray. Hard shell stuff. In the future I want to get two part expanding foam so I can cast things like this, then I want to be able to spray [insert brilliant idea] over it to make it a hard, light, durable theater prop.


Does something like this exist?
Calling: @Van and @bobgaggle
Toodleoo!
Ron Hebbard
 
I’ve used fiberglassing resin as such a coating for smaller (waterproof) projects. For a large item it might get fairly expensive, and it results in an exceedingly glossy finish.
 
This particular rock I'm building is about 3 cu ft. I would imagine it would require at least a gallon (and a fair amount of weight addition) to glass it. The glossy finish can be solved with some 80 grit and flat paint :)

I also thought about some poly resin with fibers, or as the old body guys used to call it, "tiger hair." Again, expensive and potentially heavy. Also pretty tough to apply without fibers poking actors' butts and hands.

I think (for the future) I'll invest in some 2-part poly foam, but if I go with a lighter density like a 4lb, it won't have much integrity and will need a strong coating. If I go with something more rigid and structural like 16lb, it will be rigid enough to not need a shell, but also heavy. This particular rock would be 50 lbs... which isn't too much for beefier actors to move, except for the large size making it cumbersome.

The hope is to find some kind of rigid or semi rigid coating that doesn't weigh a ton, cost a ton, or have a large need for ancillary specialty equipment to apply. My first thought was a professional version of spray truck bedliner, but the spray equipment is incredibly specialized and rattle cans are expensive and very poor at replicating the real bedliner stuff.
 
That foamcoat looks promising, if not a wee bit expensive for our budgets. Worth a shot though. Looks like I can get a gallon shipped to me for about $70.

I'll call it R&D or proof of concept. The board will like the fancy words.
 
I also found an example of what I'm hoping to achieve. There are several companies that make vehicle service ramps from a foam. One of their models (for commercial trucks) will hold 16,000 lbs per ramp and weigh just a little over 15lbs. I certainly don't need 8 tons of capacity, but you get the idea. They describe it as "space age foam" and "hard urea-based finish."

To me that sounds like 16 lb urethane with truck bedliner on it.

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@curtis73
This is a copy/paste of 2009 post for Van's Super Secret Scenic Dope aka VSSSD

For those who don't know it's my favorite concoction for treating scenic elements that need a bit of texture. If you're low on budget and can't afford "Sculpt or Coat" this is a really good alternative.

about 1 quart of latex paint (this can be pre-tinted, neutral base, or a "waste" paint, as long as it's latex).

About 4 tubes of Latex caulk. Do not use Silicone caulk. Some Latex caulk are called 'siliconized' and those are ok to use as they are still latex based.

About 2 cups of drywall mud/joint compound. Adds thickness and aids in setup time and helps leave a harder finish when dope is cured.

This is all you really need. Throw it in a 5 gallon bucket, and mix it all up with a drill motor paint mixer. Add more drywall mud to thicken it up, but not too much or it will get "cracky" when it dries, although the cracks can be very useful for some texture treatments.

For Rock. I like to carve polystyrene, then coat it with VSSSD that has been tinted to a grey or whatever base color rock I'm using. After the Dope has dried <usually 4 or so hours depending on how thick you laid it on> you can re-coat or drybrush / spatter / airbrush details on to the rock.

Cement. Mix some sand ("playsand" available at most hardware stores works great; white "ashtray" sand works well for finer finishes like sandstone, etc.) Leave the dope a whitish, beige color, keep mixing as you are brushing it on the surface as the sand will tend to settle. You can brush or roll on the cement texture. Let it dry then treat with a clear coat, Flat or Semi-gloss are best for cement. There are many brands available. Here in the Northwest, Miller Paint sells a product called Acri-clear. It's perfect.

Wood. This is a new one for me I just got worked out. Start the dope according the recipe then grab a trashed blender or food processor pour in a cup of water turn it on and start feeding strips of newspaper in. No "slicks" like the adverts or magazine sections just good old news paper. when the blender starts to bog down or it's full pour the pulp into a nylon stocking or paint strainer. Continue making pulp 'till you have enough to cover the surface you're treating. Ok Really Important Squeeze the heck out of the nylon and get as much water as possible out of the pulp. If you don't get the water out it will thin down the dope and make it hard to work with. Ok add the pulp to the dope, SLOWLY, while your running the mixer. Make sure you get the lumps out. Play with amounts 'til you get the thickness you're looking for. For Bark: I like to use latex gloves and put it on by hand, dragging your fingertips through the mix as you slop it on will give a really realistic bark look to the finish. You can put on an even coat then use a stylus to "draw" bark chunks on for a pine tree look.

There are a ton of uses. Play with these recipes and post your discoveries here. Be sure to e-mail me any really good thing you come up with . I think of VSSSD as an Open-Source operating system--it'll only get better if every shares their own unique recipes.
 
Sorry, Been completely off line for the duration of my vacation. VSSD can work as a coating for foam and be strong enough for walking on but I prefer to have a harder base under it if actors are going to be crawling all over it. I've mixed plaster or more drywall into it to make it a bit stiffer. The best thing you can do <expensive> is find a 'Procoat' dealer and tlk to them about having it sprayed. their stuff sets up hard as a rock. it is toxic during the curing but hard as a rock. beyond that would be to buy 5 gallons of Fiberglass resin at TAP plastics and paint the thing with that. You do not have to put sheeting under it. but I would go with Fiberglass sheet before I would go with 'Chopper' stlye.
 
You can do some pretty impressive things with truck bedliner, but I have to imagine that the VSSD is going to be significantly cheaper. Would you fake the bench sitting part with a board cut into the rock prop, and then coat on top of that? The board should spread the weight out across the foam and keep it from damaging underneath, and the coating should hold it all together nicely.
 
For this rock, I let a volunteer fly solo with it. She wisely started with a plywood base and screwed two 5-gallon buckets to it. Then she made a fantastic slurry out of scraps of pink XPS, sawdust, some past-its-prime drywall mud, some wood glue, and some decidedly smelly latex paint. Then she covered it with some mache of burlap and canvas and fired up the Wagner sprayer to give it a mossy rock look.

It looks great, but there isn't much integrity to it unless you sit or stand directly on a bucket. They actually look brilliant, but I whipped up the XPS rocks for the actual sitting rocks. Hers will likely be decoration further "upstream" in the creek we're suggesting.

That VSSSD looks amazing. I have all of that stuff here leftover from other projects. I might try it today. You folks are an incredible resource.

I might shorten that VSSSD to something like "Van's sauce" or "VanDope"
 

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