2D scenery

[Stuart R]

Hello all -

I have this idea of doing 2D scenic elements (not too big - no walls) using 2" insulation foam sandwiched between two skins of 1/8 luaun. The luaun would be painted in trompe l'oeil style to represent, say, a fountain, or some flower bushes, or a stack of crates (and placed upstage, generally).

There is luaun on both sides because I would like it to be able to have scenery on both the front and back. That being the case, I don't want to use attached stage jacks or anything like that to prop it up. What I'm trying to figure out is how to embed two pieces of PVC pipe (the hard stuff, not wobbly plumbing PVC) vertically in the foam layer between the skins and somehow securing it there, so that maybe a foot of each is left sticking out of the bottom.

I envision two people carrying one of these (pretty light) scenic elements onto the stage, locating two spiked holes in the deck, and then sliding the protruding supports into a (slightly wider) PVC "sleeve" extending below the deck until the piece comes to rest and can stand on its own. [The whole stage is built of legged platforms with 3/4" ply lids, so there is plenty of room to rig these sleeves where needed.]

Have any of you ever tried something like this? I'm trying to puzzle out:

1. Will 2" of pink or blue foam between two pieces of luaun be stiff enough to stand up straight, or will it wiggle and sag?
2. How can I attach the luaun to the foam so it won't peel off?
3. Once we trim the foam so none of it sticks out past the luaun, how can I treat it the raw edge so it can be painted?
4. The PVC support rods will be thinner than the 2" foam, else the holes in the deck would be huge. How can I center a thinner (let's say 1-1/4") piece of PVC pipe in the center of the scenery piece, and secure it so it doesn't pull out or get knocked out of plumb? (the right part of the drawing below shows it inserted like a lollipop stick)
5. Assuming I can find slightly larger size PVC pipe to use for "sleeves" inserted in the deck, I'm also wondering how to secure those sleeves from the underside.

If you have any ideas (even completely different solutions), I'd be most grateful to hear them.

Thanks!

 

[JonCarter]

Stuart, how large are these pieces? If no higher than, say, 5'-6', either PVC or ABS schedule 40 pipe will be more than rigid enough to hold them upright. Schedule 40 1-1/2" pipe is about 2" in outside diameter. You could cut a 2" wide slot in your 2" foam, maybe 3/4 of the height of the piece, and sandwich the pipe between your luan facing. Glue it to the luan with PVC or ABS cement, being very careful to get it vertical. You could use a piece of 2" PVC pipe as the "socket" in your platform; use a pipe flange to mount it to the underside of the platform lid. A bigger problem may be finding a cement or glue to attach the luan to the foam. Most glues I'm familiar with either won't "wet" and stick to the foam, or will dissolve the foam.

C

 

[microstar]

Or you could forget the PVC and just embed a big magnet from Habor Freight in the bottom of the scenic piece and screw a piece of strap iron to the deck. Or visa-versa.

 

[Catherder]

This is made of 4’x8’ sheets of 1” foam. We stood them up by making a hog trough from 1x3 and sandwiching the foam between that and another piece of 1x3 on the front. So the bases were upright 1x3, foam, upright 1x3, flat 1x3. These were 4’ tall at their tallest point. They held just fine.

 

[Crisp image]

I once made gravestones for Addams Family that were 4ft tall and taller. they were 2" polystyrene and on the back I had another 2"glued along the bottom with a slot in it to hold 1kg of lead.
They were light and easy to move but stood quite well. It is all about the center of gravity (COG). Get the COG right (as low as possible) and the rest is easy.

 

[DRU]

1. 2" foam with Lauan on both sides should be fine to stand up straight without sag. In building construction, these are called SIPs (structural insulated panels). They are made out of thicker foam and thicker wood, but they work as a stressed skin panel to provide great strength for their weight (and much better insulation for homes, but that's not an issue here).
2. Stay away from any glue or contact adhesive that has acetone. It will eat the foam. In the past, when I attached foam to wood, I used 3M 30NF Green Glue. It's a contact adhesive that you paint on both surfaces, let dry, then apply pressure to adhere the surfaces. I usually had to apply 2-3 coats on the foam because it soaked the glue up. Make sure to put weight on it overnight to get a good connection. You can find it on BMI Supply's website.
3. I would use Bondo. That should fill in any gaps and allow you to sand it smooth to what you need.
4. I don't think you would need to necessarily center the pipe in the foam for this to work. If the pipe was offset to one side in the foam, it wouldn't change how it functions. If you want it to be centered, take 2 1" sheets of foam, route a slot in each half the size of the pipe, and then marry them together. That would be an extra step, but if being centered isn't a problem, just glue one side of the Lauan, route a slot for the pipe on the other side of the foam, and apply Gorilla glue to attach it. The foaming action of the glue should fill up the corners of the slot a bit for a better hold, and you can sand it off before applying the other sheet of Lauan to the slot side.
5. Do you need it to lock in place? If you could have someone under the deck, buy some 1-1/4" pipe flanges and mount them to the underside, then have a crew member with a hex key lock them in place. It should work with PVC as well as with steel pipe. If you can't do it, I would buy flanges for the next size up of pipe that can slide into other (1" and 1-1/4" comes to mind). Mount pipe flanges for the larger size on the underside of the deck and on the floor, then put a pipe between them plumbed vertical. The flanges would keep the pipe straight, and you could the smaller pipe size mounted in the foam pieces through the deck and into the larger pipe without much issue.

 

[kicknargel]

Must point out that while insulation foam is often used on stage, it is pretty flammable and pretty nasty when it burns in terms of noxious smoke and dripping molten plastic. At the least I would make sure it's fully encapsulated, say by thickly coating the edges in Rosco Foam Coat or Jaxsan or a product we like called Acroflex and painting the whole thing with a retardant additive in the paint. Whether that's enough to pass muster is not for me to say here; talk to your AHJ.

Green Glue mentioned above is a good choice. There are also liquid nails-type products that can do the job; check the labels.

Another solve for the peg feet would be to sandwich in some wood blocking at 2" thick that would give you a more secure attachment for PVC, or wood dowel, or steel rod, etc.

 

[Van]

I agree with all that was said above. You can seal the cut edge with Muslin Strips coated with VSSSD. Be sure to mix in in either a Flamex or F1 Flame retardant paint additive; it's che3ap and great insurance.
As far as securing he PVC stakes: Man, So many ways to go about it. Cut a couple channels in the foam set your PVC in there then slather in some gorilla glue and spray lightly with water. G-Glue is a polyurethane and reacts by expanding in the presence of water. It typically just pulls water out of the wood our atmosphere but when used in foam there's nothing for it to adhere to. The other would be to use low expansion Polyurethane insulating foam as a glue to hold the stakes in. Again, The spray foam is Flammable so you would want to use a flame retardant on all other surface of the piece, or use the Fire retardant type of spray sealer.
Another way to increase stability would be to frame in a socket to the floor. Instead of just a hole in 3/4" ply add a short box under the ply to act as additional support.

 

[MPowers]

Have you considered Gator Board? It is a commercial product foam sandwiched between two rigid sheets fiberboard. A commercial version of what you are planning. It seems a bit pricy at first, but you have no cost for adhesive, no labor costs, no time frame for assembly. It is extremely ridged and strong. Takes paint well. I have used it out doors. It is available through most big box stores by order only, not in stock. Home Depot, Lowes, Amazon etc are all listed on the web site. Just google to find local sources.

 

[Stuart R]

Have you considered Gator Board? It is a commercial product foam sandwiched between two rigid sheets fiberboard. A commercial version of what you are planning. It seems a bit pricy at first, but you have no cost for adhesive, no labor costs, no time frame for assembly. It is extremely ridged and strong. Takes paint well. I have used it out doors. It is available through most big box stores by order only, not in stock. Home Depot, Lowes, Amazon etc are all listed on the web site. Just google to find local sources.

I'll check it out. Thanks!

 

[Stuart R]

Must point out that while insulation foam is often used on stage, it is pretty flammable and pretty nasty when it burns in terms of noxious smoke and dripping molten plastic. At the least I would make sure it's fully encapsulated, say by thickly coating the edges in Rosco Foam Coat or Jaxsan or a product we like called Acroflex and painting the whole thing with a retardant additive in the paint. Whether that's enough to pass muster is not for me to say here; talk to your AHJ.

Green Glue mentioned above is a good choice. There are also liquid nails-type products that can do the job; check the labels.

Another solve for the peg feet would be to sandwich in some wood blocking at 2" thick that would give you a more secure attachment for PVC, or wood dowel, or steel rod, etc.

1. 2" foam with Lauan on both sides should be fine to stand up straight without sag. In building construction, these are called SIPs (structural insulated panels). They are made out of thicker foam and thicker wood, but they work as a stressed skin panel to provide great strength for their weight (and much better insulation for homes, but that's not an issue here).
2. Stay away from any glue or contact adhesive that has acetone. It will eat the foam. In the past, when I attached foam to wood, I used 3M 30NF Green Glue. It's a contact adhesive that you paint on both surfaces, let dry, then apply pressure to adhere the surfaces. I usually had to apply 2-3 coats on the foam because it soaked the glue up. Make sure to put weight on it overnight to get a good connection. You can find it on BMI Supply's website.
3. I would use Bondo. That should fill in any gaps and allow you to sand it smooth to what you need.
4. I don't think you would need to necessarily center the pipe in the foam for this to work. If the pipe was offset to one side in the foam, it wouldn't change how it functions. If you want it to be centered, take 2 1" sheets of foam, route a slot in each half the size of the pipe, and then marry them together. That would be an extra step, but if being centered isn't a problem, just glue one side of the Lauan, route a slot for the pipe on the other side of the foam, and apply Gorilla glue to attach it. The foaming action of the glue should fill up the corners of the slot a bit for a better hold, and you can sand it off before applying the other sheet of Lauan to the slot side.
5. Do you need it to lock in place? If you could have someone under the deck, buy some 1-1/4" pipe flanges and mount them to the underside, then have a crew member with a hex key lock them in place. It should work with PVC as well as with steel pipe. If you can't do it, I would buy flanges for the next size up of pipe that can slide into other (1" and 1-1/4" comes to mind). Mount pipe flanges for the larger size on the underside of the deck and on the floor, then put a pipe between them plumbed vertical. The flanges would keep the pipe straight, and you could the smaller pipe size mounted in the foam pieces through the deck and into the larger pipe without much issue.

Some great solutions - thank you! Right now I'm focusing on how the PVC is "received" in/under the deck. I thought of getting some pipe flanges and affixing a 1' length of pipe, screwing them to the underside of the stage (under each hole), and then sliding the PVC into those. Just having trouble with sizes. It would be nice if everything could be PVC but I'm having trouble finding a 1"-2" CPVC (rigid) pipe that will slip into another PVC pipe just a little larger, which in turn will fit in a PVC pipe flange. I'm seem to be asking to much of the universe. I suppose I could use standard (metal) pipe flanges and threaded pipe under the stage, but that feels like overkill (and $).

 

[Stuart R]

Stuart, how large are these pieces? If no higher than, say, 5'-6', either PVC or ABS schedule 40 pipe will be more than rigid enough to hold them upright. Schedule 40 1-1/2" pipe is about 2" in outside diameter. You could cut a 2" wide slot in your 2" foam, maybe 3/4 of the height of the piece, and sandwich the pipe between your luan facing. Glue it to the luan with PVC or ABS cement, being very careful to get it vertical. You could use a piece of 2" PVC pipe as the "socket" in your platform; use a pipe flange to mount it to the underside of the platform lid. A bigger problem may be finding a cement or glue to attach the luan to the foam. Most glues I'm familiar with either won't "wet" and stick to the foam, or will dissolve the foam.

C

Great ideas, Jon. I don't work with PVC much, and am struggling to find a PVC pipe flange that will accept Schedule 40 2" PVC pipe.

 

[JonCarter]

Great ideas, Jon. I don't work with PVC much, and am struggling to find a PVC pipe flange that will accept Schedule 40 2" PVC pipe.

Threaded schedule 40 pipe is all the same--steel, PVC, whatever. Use 2" steel pipe flanges on the bottom of the deck with a foot or so of 2" PVC screwed into it. 1-1/2" PVC pipe from the bottom of your set piece should slide into the 2" and hold the piece vertical w/out too much slop, or at least not enough to worry about.