Heat Forming Foam

[TwinMustang]

Alright, so I'm trying to put together some foam bits. I need to apply heat, but I've run into a snag; I don't have my heat gun (recently moved, so it's in storage) and I can't afford to buy another right now. I have a hair dryer, but I don't think it puts out enough heat. Perhaps the oven? Set it as low as it goes and leave it in for a couple minutes?

T

 

[Reclaimara]

I wouldn't advise on using the oven as EVA foam produces smell that can be toxic (I've heard of some pet died when a cosplayer was crafting suit and using heatgun - the foam always produces this weird smell, too much of it might have been the cause) and you cook your food in the oven. So... I wouldn't really do it myself, but it's your call.

Hairdryer isn't bad, but it isn't strong enough, but it still produces some heat.

If you aren't afraid, go with oven. Or try to buy/lend another heatgun or well, hairdryer... There aren't really any alternatives...

 

[Ashgro]

i agree with palmer here but would really not recommend a oven you dont want toxins in there

 

[TwinMustang]

Thanks!

Might end up waiting til spring anyway, since it'll be too cold here to do any finish work. I've been considering scrapping the foam helmet and fibreglassing pepakura instead. Again, it'll wait til spring, but I'm much better with fibreglass than foam lol

 

[TwinMustang]

Has anyone determined the "Orientation Temperature" of EVA foam? In thermoplastics, that's "the temperature at which the polymer first becomes amorphous and will accept new shapes without causing internal stresses"


​In other words, do we know what temp the foam must be brought to in order for it to maintain the shape given to it?

 

[arma358]

I have no idea off the top of my head, though it sounds like a material property that should be fairly easy to find in a table....I'll hunt around and ask some people.

Has anyone determined the "Orientation Temperature" of EVA foam? In thermoplastics, that's "the temperature at which the polymer first becomes amorphous and will accept new shapes without causing internal stresses"


​In other words, do we know what temp the foam must be brought to in order for it to maintain the shape given to it?

 

[combinestrider]

Can't really think of anything that'd be safe. Your best bet is probably just to wait or buy a new one and return it in a week or so.

 

[Ruby]

I don't know how well this would work, and you would have to be very, very careful, but what about a butane torch?

 

[TwinMustang]

It would cost more to drive to the store than to buy the best heat gun available. It's 2+ hours away, which is why I'm trying to find alternatives. I could fiddle with the wiring and maybe get some more output on the hair dryer, but I don't really want to do that for fear of burning out the components.

As for the orientation temperature, I haven't been able to find any tables for EVA foam, mostly because of the variations of content of EVA in the foam.

 

[TurboCharizard]

Just did a search on generic EVA foam material properties and from a few different sources the service temperatures that EVA foam can operate in are -70C/+60C without losing expected properties.

The softening point (good for forming) average is ~65C which is heat gun territory when fanning over with the gun as you do.

The melting point (bad for fumes and structure) average is ~90C so I can pretty safely say keep that foam slab out of the oven because that's 200F where most ovens are for their lower temperatures.

For an example data sheet that I found take a look at any of these linked through MatWeb which are different densities and cell thicknesses.