Help with Warts

Occasionally I get a kid with a case of warts, usually on his hands. Usually I’m able to get rid of them using over-the-counter Compound W type treatments. One of my current kids has a few that have not responded to several months of this treatment. His pediatrician suggested suffocating them either by painting them with nail polish or by sticking little pieces of duct tape over them. If this doesn’t work she said that we could make an appointment and she would freeze them off, but that this would hurt a bit.

Has anyone successfully treated warts by suffocating them? Are there other ways that work and are painless?