Expanded foam molding

[kristof65]

Quite a few years ago (uh, over twenty), I had a catalog that included some molds and materials for making a variety of things out of styrofoam - the expanded beads type foam. The molds were for things like balls, ornaments, even a pith helmet. Basically, they were some sort of aluminum (I think) mold that you put a measured amount of unexpanded beads in, screwed the two halves together, and immersed in bioling water for a few minutes. The heat would expand the foam beads, filling the crevices of the mold.

 

I recently decided I wanted to look into this again, but for the life of me, I can't find anything similar or of the sort I remember. Anyone have any clue of what I'm talking about, and any direction they can point me towards suppliers and the like? I'm guessing I don't have the right combination of terms and technical jargon to find what I'm looking for. Thanks

[kristof65]

<sigh> This is getting to be a frustrating search for information online - I can find out everything about the process except suppliers for what I want to do. I'm posting here again in the off chance that someone knows something (or has better google-fu than I).

 

Here's a link to the process I'm talking about:

http://www.eps.co.uk/newsletters/2002_1_fe..._1_2_school.htm

[ixminis]

These folks have links to sculptors... the sculptors may lead you to their materials sources... or this site might do it... I had success using "EPS polystyrene" in google...

 

not what you are looking for?

 

http://univfoam.com/products/miscellaneous/

[Joe Kutz]

Quit while you are still clean on this one...

 

What you are looking for is Expanded Polystyrene Foam Casting - and it has largely been replaced by 2 part urethane foam casting for hobbyists.

 

The EPS is provided in virgin form from companies like ULine and America Foam. However the beads are so light, that moving in the same zipcode will cause them to blow all over the place, and it becomes even worse when you try to touch them...since they are so sensitive to static charges (I think I still have a picture of a pissed off cat, which got curious back when I was dealing with this stuff...covered head to tail in white beads).

 

You then needed a pot big enough to hold the mold, and boiling water...and a method of dealing with the two.

 

When the finished product was removed from the mold, it continued to expand...that is why most molded EPS items look a bit on the deformed side, like it has some form of disease causing it to swell up.

 

You used to be able to buy molds from a few dozen different companies, but due to changes in the materials available - most the remaining molds are used for taxidermists and duck decoy builders. If you do a google after the "EPS foam duck decoy" you will get plenty of useful hits.

 

The newer method (preferred by most hobbyists), uses no heat, no beads and can be done using homemade molds. Fiberglass molds are the longest lasting, but more difficult to build. A lot of people will use simple RTV molds with an expansion box around it. The urethane mold works great since once the foam has cured it will no longer expanded.

[kristof65]

Quit while you are still clean on this one...

 

I'm starting to figure that out.

 

What you are looking for is Expanded Polystyrene Foam Casting - and it has largely been replaced by 2 part urethane foam casting for hobbyists.

For what I had in mind, I was trying to stay away from the urethane foam or resin casting for a variety of reasons. But I'm starting to figure out why it's replaced it for hobbyists and short production run stuff. A lot of the stuff I'm finding indicates that the hobbyist molded EPS isn't as sturdy as the "pro" stuff, and has even more of a tendancy to crumble.

 

I'm either going to have to accept a different construction method for what I had in mind, or a much bigger production run.

 

Thanks for the input.

[Buggeye]

If your looking into different ways to build stuff you may want to consider Extruded polystyrene instead of the expanded. Its the blue or Pink insulation foam commonly used for wall insulation. Probably the best place to get tools for working with this stuff is at Hot Wire Foam Factory. There are some videos on the site that demonstrate their versatility. I used the Factory to build the Greyhawk Arena WIP Greyhawk Arena Finished .

 

Having only the Factory, my building options are limited but still impressive (especially after watching the instructional DVD). But the handheld tools open up tons of options, a staggering amount really if your good at freestyle sculpting.

[kristof65]

If your looking into different ways to build stuff

 

Not exactly, but it's hard to explain what I'm thinking about doing without giving the idea away entirely - since this is potentially for profit, I'm reluctant to disclose the idea anywhere, even if it's a forum unrelated to the idea. Once I've done some more research into my options - like whether it's plausible or not, I may post additional info.

 

I used the Factory to build the Greyhawk Arena WIP Greyhawk Arena Finished .

 

I remember that arena - quite awesome. I've been looking at hot wire cutters for some other projects, so I appreciate the link.

[Joe Kutz]

What you are looking for is Expanded Polystyrene Foam Casting - and it has largely been replaced by 2 part urethane foam casting for hobbyists.

For what I had in mind, I was trying to stay away from the urethane foam or resin casting for a variety of reasons. But I'm starting to figure out why it's replaced it for hobbyists and short production run stuff. A lot of the stuff I'm finding indicates that the hobbyist molded EPS isn't as sturdy as the "pro" stuff, and has even more of a tendancy to crumble.

 

I'm either going to have to accept a different construction method for what I had in mind, or a much bigger production run.

 

Thanks for the input.

 

It isn't as sturdy unless you overpack the pellets in order to cause them to compress tighter when expanding. If you do that - as soon as you release the molds, it will deform.

 

However the urethane foam isn't really more difficult or dangerous to work with. Alumilite sells small quantities of their 610 expanding foam for playing with the characteristics and hobby castings. I think they even have a few different tutorials on their website dealing with working with it. You also have a lot of the FX supply houses which provide information on the urethane foam casting.

 

If you have something which you would like to get info on, but don't want to share too much specifics...feel free to PM me. For various things, I have a fair amount of experience with most the low cost and prototyping methods, which I can offer up information on.

[kristof65]

I've worked with the urethane foam before, it will work, but it doesn't give me a couple of the characteristics I desire - which is hard to explain without divulging more. Thanks for the offer, I may take you up on it later.

 

 

At this point, I've located a couple of local companies that make EPS products, and I'm going to go to them for quotes as soon as I get my prototypes modeled. That will give me a much better idea of whether or not to pursue the EPS, or go for a different medium.