Does styrofoam absorb water?

[toller]

My neighbor threw out a 6' diameter hottub cover, presumably because the fabric covering had a small cut in it. It is entirely styrofoam.

I was thinking of using it either as a swimplatform at the lake, or as floatation for a wood swimplatform. The manufacturer recommends against it; although the covering is nominally waterproof (well, after I patch the cut) the styrofoam will eventually absorb water and become useless.

Is that true? Styrofoam is used for boyancy in boats and it doesn't absorb water, but maybe they waterproof it somehow. (wouldn't you think a hottub cover would be waterproof?)

[Edwin Pawlowski]

Styrofoam is Dow Chemical's brand name for their blue extruded insulation board. You may have that or something else often mistakenly called styrofoam. White expanded polystyrene is often called that by error. Over time, it can absorb some water. A well fused well made piece is fairly solid when skinned over, but it is made from a cellular structure in the material. Once the cell open or the interstices are opened, water can get in.

[Jmagerl]

Be aware that animals (beavers, muskrats) will chew the "stryofoam" into little pieces which will than float across your entire lake. A local nature area used "styrofoam" blocks to make floating sidewalks. They have since switched to prison labor with tiny aqaurium nets to fish the stuff out of the virgin wetlands as it does not decompose.

[toller]

Well, it is white, so I guess it isn't Dow's product; but it is really smooth, so that means the surface is fused?

[Red Cloud©]

The foam in hot tub covers absorbs water. When they make a hot tub cover, they wrap the foam with a sheet of polyethelyne and tape it up well to seal out moisture. That poly eventually rots and disintegrates Then the foam absorbs moisture until it become extremely heavy. That's basically what determines the lifespan of a hot tub cover. Some cover manufacturers offer an extra cost option of wrapping the foam with TWO layers of polyethelyne, which substantially increases the lifespan of the cover. The outer vinyl covering itself is not effective at keeping out moisture as there are thousands of holes from the stitching. Then there are the zippers...

rusty redcloud

[Duane Bozarth]

Don't think the blue has anything to do w/ it...

Perhaps, but the warning about critters is significant and if submerged it saturate eventually. It will be temporary at best.

[toller]

Yeh, I see it is wrapped and taped. Oh well; thanks.

[trader4]

"The foam in hot tub covers absorbs water. When they make a hot tub cover, they wrap the foam with a sheet of polyethelyne and tape it up well to seal out moisture. That poly eventually rots and disintegrates Then the foam absorbs moisture until it become extremely heavy. That's basically what determines the lifespan of a hot tub cover. "

That's basicly it and exactly what happened to my spa cover. If it's kept indoors, it will last longer. Outside, they last maybe 5 yrs or so before they get water logged and heavy. Of course they lose the insulation value at that point too.

[toller]

Would it make any sense to cutting the polyethylene off, letting it dry out in the sun for a while and then maybe putting spar varnish on it?

I only need a swim platform about 3 months a year; it has 9 months to dry.

[Red Cloud©]

If the foam is waterlogged it will take 9 months to dry! Then it will be waterlogged again less than a week after you put it in the water. It's just not the right material for what you want to do. There are other types of foam that will work. Spar varnish will just create a bigger mess, honest.

rusty redcloud

[bill a]

I think you'd be better off building a small deck on top of 4 or more "floats". One commonly free item if you can find them is plastic 55gal drums. They are super rugged, and seemingly aren't UV damaged. I see them frequently in floating docks that are quite old and in good condition. bill

[No]

Have you ever reused a Styrofoam coffee cup? I drink a lot of coffee and one time I only had access to a single Styrofoam coffee cup. I used it all day, kept refilling it, for about 6-8 cups of coffee over about 7 hours. By last cup Styrofoam was seeping coffee through. Yuck.

[wai]

replying to toller, wai wrote: I guess Styrofoam absorb very little amount of water , Styrofoam boxes we use for preserve fish in to ice , every time after wash Styrofoam box I left a bit water because I pour it not entire out of water , month by month pass , Styrofoam box was a bit heavier than before , it store moisture in it . sorry my English not fluent .

[Ed Pawlowski]

Is the original poster talking Styrofoam brand blue extruded insulation or the white foam used in sheets or molded?

Absorption depends on the quality of the manufacture. It is a cellular material and it can absorb a tiny bit of moisture. When the box is made, the plastic bead is blown into an aluminum mold and then heated with steam. That causes the beads to soften and stick together. It is then cooled and ejected. Some molders don't take the time (think cost) to get a better box and they are the ones that eventually leak.

EPS sheets used for insulation are cut from a large billet.

[Gordon Shumway]

The original poster asked the question back in 2005.

[Ed Pawlowski]

Then he probably has an answer by now from real life experience.

[DerbyDad03]

Or he drowned when his swim platform sunk. Oh, wait, you're right. Drowning is a real life experience. Brief, but real.

[Paintedcow]

I've said it before, I'll say it again. EVERYTHING posted from (some name)

[Tekkie®]

[e-mail] posted for all of us...

If you leave now the newsgroups will improve immediately.

[Ross Cumberledge]

replying to wai, Ross Cumberledge wrote: English not good but we understand. Thanks wai