Sustainable solid material that dissolves in water?

Hi everyone!

I am looking for sustainable solid material that could be dissolved in water. From web search I found out that sugar blocks, salt and gelatine dissolves in water easily, but does not fit my project requirements.

What else is available on market now?

I jsut googled “water soluble materials” and came up with everything from ceramics to fabrics.

Unfired clay is water soluble, plaster of paris is water soluble, compressed wood dust ( bound with starch) is water soluble, papier-mâché is water soluble … for that matter, iron is water soluble, given enough time.

It depends on your application.