Yes, IMPRESSING is a Scrabble word!

Letter values in Scrabble US: I 1, M 3, P 3, R 1, E 1, S 1, S 1, I 1, N 1, G 2.

Is it a valid word?

IMPRESSING is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

have an emotional or cognitive impact upon
impress positively
produce or try to produce a vivid impression of
mark or stamp with or as if with pressure
reproduce by printing
take (someone) against his will for compulsory service, especially on board a ship
dye (fabric) before it is spun

Also: yarn-dye.