Why are crystals dried between filter papers and not simply heated to dryness?

Answer 1

Filter paper is supposed to be clean. Water in the crystals can be absorbed without contamination by pressing dry between pieces of filter papers.

Heating the crystals may cause some to decompose, as some crystals may be unstable. Or they simply decompose easily.

Answer 2

if they were heated to dryness, it would become andyrous. we don't want to lose the water of crystalisation in the crystals