Removing investment

Hi - My name is Julie & I am a jewelry student in NYC. I recently
casted a few pieces in silver I made in wax. Unfortunately, some of
the texture on the pieces (bark finish) came off when I was removing
the investment. I’m wondering if anyone has any suggestions for
carefuly removing investment…I don’t want to ruin more texture on a
piece!

Also, I’m wondering if anyone has any suggestions for finishing
platinum after it has been casted. Thanks!