Anyone know of any 'safe' alternative to expanding foam?

[BazookaJo]

I remember reading a post somewhere where a guy was building a large enterprise for vacuforming, and had done so by:

a) scaling up a paper model
b) filling in the inner cavities of the paper model with expanding foam (in effect making it solid.
c) covering the outside with bondo and then sanding it down.

Sounds like a great idea, but my worry would be the expanding foam, which to my knowledge is quite a dangerous substance, especially if you were to inadvertently start sanding it.

So the question is - does anyone know of any safer alternative(s) that would do the same job?

Thanks in advance

Paul.

[David H]

I have just employed some "Gorilla Filler" and sanded it down. Nasty dust aside what are the hazards? I am sure the instructions state it is OK to carve and sand.

BTW in our house when conducting DIY repairs and home decoration the foam filler is know as "Daddy's special helper"!

D

[SCEtoAux]

Latex Foam Sealant might be something to check out if you can not find anything else to replace the urethane based expanding foam. DapTex is one maker of the stuff.

[Amazyah]

I used to work for a Refrigerator and freezer manufacturer and my job was to fill the empty core of the fridge or freezer with expanding foam.
Our foam was made by BASF and during the 2 years that I performed this work, I attended many classes about the safety and handling of the chemicals involved.
The expanding foam available to consumers is the same stuff that we used in the refrigeration industry.
Basically, the foam is created by a chemical reaction between two chemical compounds.
Inside the can are two compartments, one for the substrate and one for the catalyst.
Basically when you press the button the two chemicals are ejected from the two inside compartments at a preset ratio. The chemicals actually mix just before coming out of the can.
The most dangerous part of the process is the actual mixing and reaction stage where you see the foam growing and expanding. Many carcinogenic (cancer causing) gases are released at this stage and two things you don't want to do is breath the fumes or smoke cigarettes near the expanding foam.
No, it won't blow up, the cigarette will absorb the gaseous chemicals from the reaction and then you are producing another chemical reaction in the cigarette as the tobacco burns and you are inhaling it.
The effects have not been fully studied but I will bet they are not pretty if this is something you do on a regular basis.
The foam created by the reaction is perfectly safe but with any substance you sand, including wood, you don't want to breathe in the dust so I suggest a dust mask.

Russell

[Erik J]

RC model construction uses the blue foam from the building supply stores and is cut to shape with a 'hot wire'. Part of the process is to put a template on each end, like stiff cardboard, and then do the cut. There are many web sites with instructions on building one. This should work for a card model like you are talking about. Another plus is that there is no chemical vapors or expansion that would burst a card model outer shell. Hope this helps.

- Erik

[David H]

Thanks Russell,

That explains the risks brilliantly. I carve and sand models outdoor but will be more careful next time.

Erik, I have used blue foam as well s expanding foam on the same model!



Not very traditional I know but it really helps support the paper skins of paper ships! Blue foam cuts and carves like soft balsa but is messy to prepare I have recently used it to form the internal support for a ships bows. Hot wire cutting to form blocks for a hull would work fine and be less messy but fiddly getting the blocks the correct size.

We could of course ditch the card skeleton as you suggest and use the hull formers as templates for a foam hull.

D

[BazookaJo]

Cheers guys.

I think a lot of people just dive in with this stuff thinking "if it was THAT dangerous - would they just be able to sell it to any idiot?".

I had the propmaking and casting handbook and remember a section on multi-part foams - they were described as being very hazardous indeed.

Maybe it's just a case of treating it with the proper respect...

Regards

Paul.

[Bowdenja]

As with the Polyurethane glues............ Do Not Get ANY on your body parts (Hands) it WILL stain them black and it doesn't come off very well.

I use my dremel and a drum sander.................. but I don't recommend it............

standard disclaimers.............

if you do use the dremel and sander and you cut, grind or remove any body parts, ie finger nails, fingers or whole hands, I am NOT responsible and you better go to the doctor and get that stuff put back on........... also you might what to throw away any other power tools and or knives and scissors you have because you are going to kill yourself one day.

Or the short version................... "you are going to shoot your eye out kid."