Got wood trim that needs to be stained? Will taping it off still allow the stain to leak onto the wall? Here's how to stain new trim "in place" with no mess. When trim can't be stained and finished before it goes on the wall, there are ways to avoid masking the wall with tape (which usually leaks stain onto the wall). Instead, try masking the back of the trim so about half extends beyond the outside edges. Then install it, stain it in place, and carefully cut the exposed tape off with a sharp utility knife. You can also put waxed paper behind trim beforehand. Again, cut it off with a sharp knife after staining. And that's the On The House tip for today.