Question: What does the particle formation look like in a sponge because even though it's a solid it has loads of air holes in?

Thomas Barrett answered on 13 Mar 2015:

It basically makes a loose kind of frame with lots of air pockets. Loose fibers in the sponge create a product that is more empty space than anything else. It is because of this empty space that the sponge can work so well. The holes between the fibers soak up the water and cause the fibrous material itself to swell. This prevents the water from sloshing right back out of the sponge. Instead, the water is trapped inside until the sponge is forcibly squeezed.

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