Styrofoam hardening ?

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AudioFeline
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Re: Styrofoam hardening ?

Post by AudioFeline »

I've used PVA on styrofoam, and acrylic paint. You could create a paper mache covering using the pva glue if you wanted thicker and stronger protection.

Daithi
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Re: Styrofoam hardening ?

Post by Daithi »

AudioFeline wrote:I've used PVA on styrofoam, and acrylic paint. You could create a paper mache covering using the pva glue if you wanted thicker and stronger protection.
Is that Polyvinyl Acetate?
Yes, at least paper applique would be easy to do and it has a proven track record as a good material for making horns.
By lining each side of the clamshell with paper applique and assembling them with silicon grease as a sealer I hope to have something I can take apart easily.
It should be a material that is hard yet not too brittle.

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AudioFeline
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Re: Styrofoam hardening ?

Post by AudioFeline »

Daithi wrote:Is that Polyvinyl Acetate?...
Yes white PVA wood/craft glue, dries white. I think you have different brands to where I am.

Try an experiment before your actual project to see if it will do the job you require.

edisonplayer
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Re: Styrofoam hardening ?

Post by edisonplayer »

Curt A wrote: Thu Oct 29, 2020 3:55 pm
Daithi wrote:
Orchorsol wrote:Styrofoam is closed cell, so it won't be possible to impregnate it as such.
Yes that is another problem, I was thinking as a last resort of pulling a vacuum on it. But that has its own problems too. I have read that given time water can percolate into the spaces between the cells as happens at sea where styrofoam sometimes ends up wet and eventually becomes waterlogged after long periods.
Looks like coating it is the easiest way out though. How to build up a thick hard coat? Fiberglass, carbon fiber or just plain old paper applique like they did in the old days?
Now, I'm really puzzled that you are worrying about waterlogging... are you using this underwater?

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AudioFeline
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Re: Styrofoam hardening ?

Post by AudioFeline »

Daithi wrote: Mon Oct 26, 2020 10:06 pm The plan was to fill the box with hard styrofoam in two parts like a clamshell, then carve a horn out of the middle of the clamshell, and then soak superglue or liquid acrylic into it to a depth of ¼ inch forming the horn while leaving all the rest of the styrofoam as raw styrofoam to absorb any stray sounds and/or leaks.
I know its a bit weird.
Just re-read this early post on the thread. I don't think styrofoam is very good as a sound-absorber, you will find there are other materials that are specifically made for this purpose that will probably work better (eg. sound-absorbant foams and woolen bats).

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Re: Styrofoam hardening ?

Post by JohnM »

Why not fill the box with expanding urethane foam, allow to cure, and then carve-out the opening. There is also a product called ‘SignFoam’ (and others) that are High-Density Urethanes (HDU). They come in varying densities and thicknesses. Not inexpensive, however.
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