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eande 2 days ago

Another one of these fascinating super absorbent materials is SAP (Superabsorbent polymer).

It is heavily used in diapers, tissues, water retention for plants, etc. SAP can absorb liquid up to 30-60 times its own volume.

https://en.wikipedia.org/wiki/Superabsorbent_polymer

dist-epoch 2 days ago | parent | next [-]

I think it's more expensive, and I'm not sure it can absorb vapor (not liquid)

It's fun that it has the same refractive index as water, so if you put clear ones in water they disappear. Then you ask someone to put their had in a bowl with them for a surprise.

btilly 2 days ago | parent [-]

My kids loved that stuff when they were young.

genewitch 2 days ago | parent | prev [-]

Aka orbees. Also useful as a soil amendment if you have clay soil, it stops it from claying so much and retains water underground for plants.

They make glow in the dark ones, which I put into a masonry jar with some distilled water and a drop of bleach, I light it from underneath with a USB LED and it glows for about an hour. Cool night time light.

Back in the early 90s they had a different name and they were irregularly shaped. This was for Soil Amendment. I think it started with a Z.

joecool1029 2 days ago | parent [-]

> I think it started with a Z.

zeolite? https://en.m.wikipedia.org/wiki/Zeolite

genewitch a day ago | parent [-]

i don't think so. It was a brand name of whatever SAP they had decided was safe for plants to bathe in. I found some about a decade ago, just by asking about water retention crystals at an agricultural outlet. I think it's cheaper to buy orbees when they're on clearance, though.