DIY background with foam filler?

[PeteJ]

I've seen a lot of DIY foam backgrounds and i was wondering if anybody has ever tried it with expanding foam filler?
it would be a little harder to carve i am sure, but could be a viable alternative to styrofoam (evil and messy) has anybody tried this though? just curious really as i have a 100litre tank sitting by my bed and i want a DIY background in it.. just mulling over ideas!

im reality i'll probably just pinch a few poly boxes from work and use them anyway.

 

[Volenti]

Expanding foam has an advantage of having a pretty random surface texture/structure to begin with (depending on how you apply it) before you even start to carve it, it also can be re-applied to fix errors, fill holes or bulk up areas after the fact.

All though personally I intend to use the foam structure only as a base to make a fibreglass based (hollow) background.

 

[wizzin]

i'm using it on my tank. What I learned was that if you don't rough the surface of the expanding foam, the concrete has a hard time sticking to it. When the EF cures, the surface is shiny and fairly smooth. I just used a utility knife and scored it in a criss cross pattern, then used rough grit sand paper to shape it down and rough it up.

One final thought. The spray foam is expensive! $5 a can and it doesn't cover very much. I went through 20 cans of it on my first attempt at the background, and that was just to fill in gaps and create changes in the surface of the blue foam I used for the bulk of the background. Of course I'm doing 10 foot x 4 foot x 4 foot surfaces, so you'd use less obviously. Point is, it may work, but it's not going to be the cheapest. Use styrofoam as the foundation, and use the spray foam to create interest. IMO.

 

[PeteJ]

Yeah, i remeber using it about 10 years ago to do warhammer scenery!
for a 100litre tank though i was planning to use a sliver of polystyrene then as you say pad it out with the foam.

when sealing something like this with a resin should you do all sides or just the front?

 

[schaadrak]

Yeah, i remeber using it about 10 years ago to do warhammer scenery!
for a 100litre tank though i was planning to use a sliver of polystyrene then as you say pad it out with the foam.

when sealing something like this with a resin should you do all sides or just the front?

If it's a urethane foam you shouldn't need to seal it. It's the solvent that's harmful so just make sure it's fully cured before adding it to the tank.

Here's a link to a great looking foam background that has a pretty detailed step-by-step instructions with it.

 

[rdeandavidson]

That link was awesome lotta ideas rolling in my head!