Among the OGRE miniatures I was given to paint by my friend there were two OGRE's, a Mk. III and a Mk. V. Both had some paint on them along with dust and age. I like to start off with a fresh palette, and I decided to strip the paint from these models. You start off with a jar, some painted minis that need to be stripped, and Purple Power.
Initial directions are simple: put miniatures in jar, and then fill jar so that all miniatures are submerged in Purple Power.
Next comes the waiting. I recommend waiting at least 24 hours before cleaning the paint, and I usually wait more than that. A couple of days should be enough. The ones pictured above sat submerged for a month or two. I even had a model soaking somewhere between nine months and a year. There is little risk to metal miniatures, and plastic seems to do ok, but suffers some loss of hardness. Here's what the jar looked like before I pulled them out.
When you're ready to take the miniatures out I HIGHLY recommend using a pair of disposable gloves. Purple Power is used to clean engine parts from cars, and it is mildly caustic to bare skin. The first time I used it I didn't think it'd be a big deal to let my hands get exposed to it as long as I washed them right away. Less then an hour later my hands had a numb sort of tingling, and were peeling like they had been sunburned badly. Purple Power is a very potent cleaning agent, and anytime your hands/skin may be potentially exposed to it I recommend caution.
Using a cheap or old tooth brush you'll want to scrub the miniatures vigorously. Do not rinse them first. My experience has shown me that exposing the metal to water makes it more difficult to remove the old paint. When scrubbing there will be a foamy mess. Just keep scrubbing vigorously, and when done scrubbing rinse with water. Try to get any last spots you may have missed before setting aside to dry.
Once the pieces are dry I recommend assembling and primering them right away. The first time I had learned how to strip paint was when I commented on a friend's model. It was bare metal but had this swirling pattern of rust that looked incredibly authentic. Turns out it was authentic. Something within the acidity of the cleaner makes the metal more susceptible to rust and corrosion. Primering the models helps to coat the metal and prevent any corrosion. Painting does as well. Anything that coats and covers the bare metal should suffice.
You'd have a difficult time telling the difference between these models and ones purchased fresh from the store. Whether picking up second-hand miniatures or dissatisfied with an earlier paint job you can use this method to help restore them to a blank palette.