As water is an excellent solvent and is also naturally abundant, it is a ubiquitous solvent in chemistry.

It can be any solvent, but let's just think about water in its liquid state.

The proteins are eluted by a gradient of increasing amounts of an organic solvent, such as acetonitrile.

This relatively simple process uses only one amide solvent, and therefore spinning can be done directly after the polymer production.

So the general rule of thumb is, if you're dealing with a solid in a liquid solvent, lowering the temperature will decrease the solubility, because it's harder to jam the molecules in there, and increasing the temperature will increase the solubility.