Avoid paint strippers by removing paint from old hardware using a hot water bath.
Soak painted hardware in hot water to loosen many layers of paint and make cleaning much easier.
If you want to strip paint from metal without the nasty fumes and mess of chemical strippers, just fill a slow cooker with water and set the dial to high. The heat and moisture will soften the paint, and often it will fall off as a single piece.
This works on oil, latex and spray paints, but it may not remove some clear finishes like lacquer. Cooking the hardware may stain or contaminate the pot, so use an old one or buy a new one for less than $20. This method won't harm hardware made of non-rusting metals like copper, brass or aluminum. You'll end up with a little rust on steel—not enough to ruin hidden parts like hinge pins or screws, but possibly enough to roughen shiny surfaces. If the steel has a plating like chrome or brass and the plating is already flaking off, this method will cause more flaking.
Some paints will loosen within a couple of hours, but for best results, plan to cook the hardware overnight. If the paint doesn't fall off by itself, scrub lightly with a stiff plastic brush. The paint will harden as it cools, so scrub the hardware as soon as you pull it out of the water. The paint may contain lead, so catch all the sludge and throw it in the garbage. To clean the metal and restore its shine, use a metal polish like Brasso or Noxon.