Painting - Painting lines without bleeding

I noticed, on a design show, a designer applying a clear product along the edge of the painters' tape before she began painting, and was wondering what that was. (She was painting stripes on the wall.) We have orange peel textured walls and no matter how careful I am the paint seems to bleed under the tape. I've also heard of putting caulking along the seam of the painters' tape to prevent bleeding, but haven't talked to anyone who knows much about this. Any help you can give me to paint clean lines would be helpful.

Thanks!

The cleanest lines made by a brush are always done by hand. That said, there are a couple tricks to do when using tape. Rubbing a little light-weight vinyl spackle along the edge will work (this is called 'bridging'), as will a very thin coat of acrylic matte polyurethane. Against orange-peel texture, or any texture for that matter, then all bets are off. It might work, it might not. Test drive any technique in an inconspicuous spot before doing it everywhere.

I saw an article by a profesional painter and he says for the few instances he uses tape he will only use the Sherwin Williams pro tape. I haven't tried it. If you try it let us know how it turns out.