[anders94]

Our lab ordered the radical TEMPO, but it arrived as a giant lump, which could be due to it melting during transport.
The chemical is supposed to be a powder. Was thinking of doing a recrystalisation, but don't know if there is something to consider before doing that for a radical.

[pgk]

Probably, TEMPO (bp: 33-38oC) melted during transport and then, slowly re-frozen to form the giant lump. Besides, (accidental) absorption of humidity helps this kind of appearance.
Anyway, recrystallization of TEMPO (with some loss) is described in the link, below:
https://www.tcichemicals.com/en/gb/support-download/tcimail/backnumber/article/146drE.pdf

[wildfyr]

Nah, go ahead an recrystallize. Or even just dissolve it in a good solvent and dump wholesale into a bad cold solvent to precipitate it and re-powderize it. Maybe ethanol into ether?

As always, try with a small amount first, then do the rest.