How do I get large expansion?

John Tomlinson

Processes like thermal expansion produce very slight expansion/contraction. I am looking for a material/process that expands significantly, say 10% to 20%, in the room temperature range while maintaining its' shape. I know some materials expand significantly when wet, but don't know any numbers or where to locate such data. It would be bonus if the material could be put in a mold. I am doing an art project and would like to scale up some of the elements I am using.

brewnog

What kind of material?

Tell us some more about your application and we might be able to give you some pointers. Does this expansion have to be repeatable? Does it have to be with temperature changes?

PerennialII

Aren't there some porous materials that would suit this kind of purpose pretty good, you could do the expansion with moisture (then again I could be completely wrong)? With respect to temperature (and probably moisture as well) some polymers do expand quite a bit but don't think (know) if they can go as high as 10-20% ...

Artman

Foam insulation, but it would need a mold.

PerennialII

But foams of course, actually if you can put it in a mold how is the expansion relevant ... or if want to use just a single mold and expand it up from there.

John Tomlinson

I would like to make a mold of an object, put the material into the mold, then do something to make the newly molded object expand to a size greater than the original while retaining the original shape.

FredGarvin

This may be a silly question, but why not just make the mold the size you would like to end up with? There's no way you are going to get any kind of dimensional stability or similarity between the original and scaled parts by the way you are thinking.

What, EXACTLY, is it that you are doing?

Gokul43201

I second this sentiment. Why all this trouble for a paltry 20% increase in size ?
I tend to think so too, but this depends on your tolerances.

John Tomlinson

There are two possibilities I have in mind. When I make molds and then fill them with clay/ceramics the piece shrinks 10 to 20 percent. I would like to make a mold of the expanded piece so that when I make a ceramic object from it I can get something that was the original size. A second use I would have is that if I can get expansion significantly greater than 20% I could use this to make molds of objects that were scaled up significantly larger than the original. I think I might be able to offset the 'dimensional instability' by not casting solid. If there were a high degree of dimensional instability, that might be OK too. I might not mind if the objects were distorted as long as they were visually interesting.