Where am I going to find high-density foam?

[corksil]

I have another interesting project and for this one I need high-density foam.

Preferably closed-cell so it won't absorb water.

I need blocks that are roughly 11" x 11" x 7".

Stuff is available online but I know something like this can be found for very cheap or free if one knows where to look.

Preferably high enough of a density that I could set a cinder-block on one of the foam bricks and have it not compress the foam more than a 1/4" or so. I'll bet there are all sorts of standards and ratings for describing the density of foam but I am not a foam scientist so I don't know the technical terms.

Where might something like this exist? I think those foam mattress toppers are a little too soft for this purpose, and they are open-cell foam which is not idea. Also would be hard to find one that is 11" thick. There are also pre-cut bricks of foam sold on ebay as "yoga blocks" but I can't find any big enough and they are pricey.

Ideally the foam would also be black.

I need a piece about the size of a queen mattress, I'm sure I could figure out how to cut it down to the dimensions that I need.

Anyone?

I swear.. my threads keep getting stranger and stranger.

[csmith12]

Originally Posted by corksil

I swear.. my threads keep getting stranger and stranger.

Lol, but I am learning new things.... so no worries here.

[corksil]

^^ hell yeah bro. That's what it's all about. The pursuit of knowledge.

So I've done a bit of research and most of the foam retailers online are pretty pricey. To find a mattress-sized block of foam of appropriate type and density I'm looking at over 200 bucks and then shipping charge on top of that.

There has got to be a better option. If the weather clears up I might check out a few fabric stores to see if I can find anything but the whole point of this project is figuring out how to do it without spending much.

So far a mattress topper out of a dumpster seems like my best option.

Where would cinder-block sized bricks of stiff foam be found? What are their typical uses?

There's loads available online for things called "foam pits" but too expensive and would make this project not worth undertaking.

Holy sh!t look at the size of these things..

[JohnnyBravo]

Like foam insulation at the hardware store???

[corksil]

Typically there are two types of "foam" with various independent properties.

Closed cell foam does not absorb water because the tiny little air bubbles in the foam are sealed. Think 'bubble wrap.'

Open cell foam will absorb and hold water. Think 'sponge.'

There are various grades of foam; each with their own unique chemical properties. Polypropylene, polystyrene, polyethylene, HDPE (high-density-poly-ethylene), LDPE (low-density-poly-ethylene), polyurethane, PVC (poly-vinyl-choride/PVC) and a few other common ones.

The word "foam" is actually a misnomer because when people hear the word "foam" they typically think of a sponge or something that is squishy and absorbent.

"Foam" has a working definition of "a mass of tiny bubbles" -- and all plastics are a formulation of such, each with varying and independent properties. Most plastic compounds consist of an extruded base compound, which is "cured" into a finished product with the use of an accelerant or hardener. From a chemical standpoint this is the same method of action accomplished by jb weld or bondo, or any epoxy/polyester casting resin with a two-part mixture.

All of this is probably way more information than you wanted to read, but maybe it will be helpful if you have a project in the future and need to know about this stuff.

[corksil]

So far this is the best and cheapest option I can come up with but it's not available in the dimensions required for this application.

http://www.ebay.com/itm/201295842768

If anyone is curious how to cut foam.... there's a convenient youtube video available.

https://www.youtube.com/watch?v=SCbEeW_n7OU

[Triple Jim]

Electric kitchen knives can work well for soft foam. I used a bandsaw to shape the foam of a motorcycle seat I rebuilt, but you have to be careful to not let the foam get caught between the blade and the opening in the table. Generally a bandsaw works well for medium to firm foam. Hot wires are especially good for things like Styrofoam.

[corksil]

I'm thinking I can modify the head of an exacto knife to fit in my soldering iron instead of a soldering tip.

That would give me an electrically heated razor which should cut it pretty well.

What's the difference between close cell and eva foam?

[Triple Jim]

EVA is a type of plastic, ethylene-vinyl acetate. Closed cell is a type of foam, as you described above.

[corksil]

This is tricky because EVA is the common term to describe a "yoga block." Then again if you think of EVA in terms of what you probably consider to be "plastic" -- it's misleading because one would assume that plastic is rigid.

Then again this picture leads me to believe that these yoga blocks advertised as ethylvinylacetate (EVA) are indeed pretty damn rigid.



Pretty damn rigid indeed. No pun intended.



I'm also seeing foam anti-fatigue floor mats advertised as EVA "high density."

[corksil]

If I could find yoga bricks in a bigger size that would be perfect but for some reason they are all the exact same 9x6x3 or 9x6x4" sizes.

Then there's this which is probably EVA with a vinyl slip-cover to protect it from dirt by 62 bucks for a big foam brick is still kinda pricey.

a high-quality brand of polyurethane foam products for commercial use. After 60 years of development, this product is guaranteed to be soft, durable, colorful, environmentally unique, and fun. If you can't find exactly what you need, Foamnasium can even create a product in virtually any shape you want. Play blocks made from soft, resilient vinyl. Anti-microbial and anti-bacterial protection. Set includes handle for easy transportation. Choose from variety of colors. Dimensions: 21L x 21W x 20H inches.

[Triple Jim]

Plastic is a generic term. Lots of elastomeric foams are made from things like polyurethane and polyethylene, which are plastics. The point is EVA defines a chemical compound, and closed cell foam defines a configuration.

Anyway, if having that stuff around attracts people like the one(s) in your photos, I'll see if I can pick up some too.

[corksil]

Yeah I'll let you know if I figure out where to buy this EVA foam.

It seems that EVA is available in varying densities -- and the b!tch about this is that supposedly varying densities are considered "proprietary" and have been patented and trade-named. Doesn't seem right from a scientific perspective that someone could create material, use it for a specific application, and then patent that application but that's a different discussion.

EVA foam in 5.8lb/ft^3 density seems like the ideal material for this project.

[corksil]

I can't figure out why this stuff is so hard to find in blocks. It's very available in sheets and small chunks (like childrens building play blocks) but anything over a couple inches thick is unheard of.

Looks like people are also using EVA for fishing rod handles and grips.
http://www.northeastrodbuilders.com/...ly-blocks-eva/

[SLOWn60]

A Queen size mattress is 60"x80" and you want it 11" thick.
Lets do the math:
11x60x80= 52,800 cubic inches of foam.
Divide that by 144 (# of cubic inches in a board foot) = 367 (rounded Al!) board feet of foam.

I don't know what a cinder block weighs but it is irrelevant for a cost calculation but quality (how long it will maintain your needed specification: life of the foam) is. Density is the cost variable as well as composition (what it's made of) and if open or closed cell. Density is the quality: the higher the density the more material, the longer the life. Compression is the resistance (pounds per square inch to compress 1").

There's much more I could blather on about but in the interests of brevity and time constraints:

Closed cell will cost much more than open cell if you want the foam to rebound and not just crush. Open cell, better quality (good, better, best) 2 1/2 lb density foam wholesales for about $2 a board foot. Perhaps you can get it for half that in the states but I doubt it.
So: 367 board feet of foam @ $2 a board foot = $734 wholesale cost.
Closed cell: If you have to ask; you can't afford it!

[corksil]

Yeah I have realized that higher density EVA foam is typically more expensive due to the fact that it requires more "material" to create. That is why it's more resistant to squishing force, why it is more brittle to break/tear, and heavier as well.

I mentioned the cinder block for a rough size estimation of the pieces I'm looking for. I don't know what a cinder block weighs either but we can agree that it's irrelevant.

There is also an aspect of temperature involved with the creation of EVA foam because all of the chinese wholesalers list the hardness in terms of temperature instead of durometer like we do in the states.

Waiting on replies to a few emails but progress is being made.