What is the best method to strip layers of paint off old doors/mantle?

Have you tried Citristrip which is a safe non-toxic stripper?

I agree with Citristrip. It a gel/paste that can remove layers of paint. It can be a process, but proper prep is the key.

the quickest way is to have the piece dip stripped. a furniture restoration place should have a vat big enough. the piece is completely covered- no potentially toxic lead based paint particles floating in the air. some places are reasonable, some aren't. check around.

Sand it with an 'orbital sander'...NOT A PALM sander...there's a huge difference. Most orbital sanders are adjustable speed, so you can start out slow & pick up the speed when you've become comfortable working with it. Always be careful when doing edges or corners, so you don't lose your grip on the sander. Start with a 80 grit sand paper to do the beginning work of stripping; then go to the 120 or even the 180 grit [larger numbers are finer grit = smoother finish]

I too would use Citristrip for removing layers of paint from old doors. Don't rush the process. You'll be happy with the end result if you do it right the first time. Best of luck.

The other day I was searching through DIY projects for removing paint off of old door knobs. Put the door knobs and hinges in a slow cooker add water and Dawn dish soap. I put the slower cooker on High and left it on all night . In the morning I used Tongs to pull the hot door knobs out of the slow cooker, the next morning the paint was mostly off I used a thick cloth to wipe the rest of the paint off while still hot, the paint came off so easy

I always use Citristrip. Cover it with plastic wrap after applying to keep it wet and working.