Poor plating results on steel sand-blast parts

Out-sourced some steel parts for black zinc plate at a local plating house. When received back, the finish appeared nothing like zinc plate, but rather a flat black chalk like finish that scratches rather easy. These parts were sand-blasted previous to plating. My question, is this a typical result to expect as a result of the sand-blasting. What can we do to prevent this from happening again? Thanks so much for any and all replies.

Gary,

The brightness, gloss, of the finished product is influenced heavily by the condition of the base material. In this case, a sand blasted surface would be very hard to "brighten" during the zinc plating process. I would expect to see a matte black finish after chromating. And yes, the chromate will scratch easily, especially on a blasted surface. However, the finish should not be "chalky" or "powdery" or easily rub off. If you need a better looking finish, avoid blasting.