Playing with foam

[Tropicok]

Since it's a nice day to stay home, I'm playing around with the expanding foam stuff. Great fun! I have sprayed vertical lines up and down a long piece of aluminum foil and created some knotholes and a shelf or two trying to make a natural tree trunk look. I can see I will have to do some carving. More fun! And then the best part, painting. I have only lime green non-toxic paint handy but that's no problem to get other colors. I am hoping the hardened foam peels off the foil. If not, no problem. I thought a removable background will give me more options that spraying directly on the glass. I will let y'all know how this works out. Any comments welcome.

[Frogsong]

Since it's a nice day to stay home, I'm playing around with the expanding foam stuff. Great fun! I have sprayed vertical lines up and down a long piece of aluminum foil and created some knotholes and a shelf or two trying to make a natural tree trunk look. I can see I will have to do some carving. More fun! And then the best part, painting. I have only lime green non-toxic paint handy but that's no problem to get other colors. I am hoping the hardened foam peels off the foil. If not, no problem. I thought a removable background will give me more options that spraying directly on the glass. I will let y'all know how this works out. Any comments welcome.

The foam is not toxic?

[Tom Highum]

when dry I do not believe it is.

[John]

Polyurethane foam is pretty much inert when it has polymerized.

[Tom Highum]

I remember Sludgemonkey saying that green or blue paints were toxic to frogs though. Had something to do with copper.

[SludgeMunkey]

Aye, green an blue paints should be avoided at all costs. Most of them are made from compounds of copper, cadmium, or cobalt. Many others are made of even more insane chemicals I cannot pronounce. I researched this pretty heavily a while back and so far only Liquitex BASICS acrylic paints in the colors of mars black, titanium white, raw/burnt umber, and raw/burnt sienna are vivaria safe.

While expanding urethane foam is a viable medium for vivaria, there are some very important facts to keep in mind. It does not matter if you use the straw color, the standard color or the black. They are all chemically identical. The real difference is one has a black pigment to make it UV stable, the others just use different mixes of propellants to give different expansion factors.

1. If you make the foam mass too big, it will cure on the outside and remain soft on the inside. This creates two very serious problems- the first being the cured mass is unstable and will crack over time to allow propellant gases from the can to escape. The second is that these propellant gases are toxic in an enclosed environment like a vivarium.

2. Expanding urethane foam is not permanent. Even covering it with paint, concrete, or epoxy, it will degrade in just a few years due to moisture and humidity. The cured foam is also unstable, rapidly expanding and contracting with temperature and barometric pressure.

3. Cure time is the MOST important factor. You must allow the foam to completely cure before painting, carving or coating it. This can take MONTHS even though the foam appears cured to you. Expect freshly carved foam to shrink a bit. I suggest at least a weeks drying time at 75F for about a week in a high humidity environment (like your bathroom or laundry room). Once you carve it, give it at least a week more to stabilize before painting and or coating it.

4. If the foam is used in the presence of water (like a waterfall or pond) even if it is painted it will shrink! If the foam is to be used like this, after it is cured you need to soak it in a bucket of water for a few days and observe it. It may warp into something you do not like.

[John]

I've been fooling around with this foam for about a week - I can see some of Johnny's points in what I've encountered so far, and an experienced friend has also echoed what Johnny has said. If I were making another terrarium I think I wouldn't bother making the background out of any kind of foam, to be honest.

[SludgeMunkey]

Carved styrofoam and acrylic concrete for the win!

[John]

Carved styrofoam and acrylic concrete for the win!

If you're trying to build muscle tone. I would rather just coat one side of a sheet of styrofoam with silicone and peat/coco fibre.

[Tropicok]

Acrylic concrete? And how do you handle or apply it?

[Tropicok]

The foam background I sprayed on a piece of aluminum foil looks fantastic especially since I carved out plant holes of the lumps. Problem is, it is not tall enough for the tank. It was just practice anyway. My friend Ken explained about about fiberglass and Bondo (sp?) but it sounds complicated and for a speedy-working professional at vivarium building. This tall tank is a work in progress and I'm not in a hurry. I've got the plastic grid cut for the bottom and some black screening in place. I need some PVC pipe and more rocks, plus a bigger background. I think I'll go the carved craft foam and press coco fiber into it.
In the meantime, I'm spraying water on the tropical plants I couldn't resist buying on sale. My little tiger-legged seems to be doing fine in the first tank and I used the tip: putting a piece of netting in the water bowl so the crickets can climb out. Thanks.