MoreDCthenBatman

I've just started Lego modification more recently and was hoping to get some advise. What I'm trying to do is spray paint a ring going around the forearm of a Lego arm, I covered all of the areas that I didn't want recolored with scotch tape but when I removed the tape there was paint underneath and not around the edge of where the tape had been covering, so I redid it with masking tape but I had the same problem. So what I need to know is is there a better way to cover the parts of the minifigure's arm that I don't want to spray paint? It seems to be going through the tape. Thanks in advance.