A couple of years ago I bought a house. One of the things I really wanted was lots of wood. I have always been impressed with houses that has well finished wood throughout. The house was almost 60 years old and had hardwood flooring. The original wooden doors were painted. Well, those were the first thing to tackle. Little did I realize what a workout my arms would be getting :) I also would like to thanks the gang at www.thinkhaus.org for creating their hackerspace where I was able to make a dusty mess on a regular basis ;)
Step 1: The Beginning
So obviously the first thing I did was take the door out of the house. I removed the door handle but left the door hinges as they too were painted and needed a good cleaning.
Step 2: Apply Heat
There are many ways to strip a door. I am not terribly fond of the chemical way to do so so I opted for the heat-gun method. For those that don't know, this is a special heat gun designed for high-heat applications. A hairdryer will not work.
I learned pretty quickly how to apply this heat. I found that if I heated the paint too much, it would simply harden and make it just as difficult too remove as pure sanding it would. I also found that after you apply the heat, you have to wait till the paint cools otherwise it's a big gooey scraped mess :/
The best way I found for this door (YMMV) was to hold the gun about 6" away from it, let the paint bubble just a little bit. The paint would seemed to generate some fumes (safety note, do make sure you are in a well ventilated area) and the paint, being evening applied and sufficiently think enough, would start to create one big bubble underneath. This is the paint literally separating from the surface and is ideal for removing.
I also learned to do it in small sections as the 'bubble' would eventually find a part where the fumes would escape and collapse, thus partially ruining a clean removal.
This shows how the paint came off in a nice section leaving a fairly clean surface(which had to be sanded to remove the old varnish and bits of paint). I was very happy as when the paint came off like this, it meant significantly less sanding/easily ruined sand paper. Plus it was kinda fun too :)
Step 4: 1/4 of the Way Done
If you are lucky, the majority of paint will come off nice and easy. I am still floored that people thought that painting wood was a good idea.
Step 5: The Door Handle Area
You will find that some paint will simply not peel off. This will usually be due to dings/scratches where the paint has filled in some sort of valley in the wood. Nothing but good 'ol sanding will get that out.
Step 6: The Edges
Don't hold your breath for anything easy on the door edges. Since the wood was nowhere near as smooth/finished as the front/back surfaces, not much peeled off here after applying heat.
Step 7: Stripped!
There we go, one side all stripped. The bulk of it came off pretty easily but there were sections that would not without sanding. I found that while I was using a scrapper to take off 'the hard bits', I would scuff/scratch the surface. This was seemingly unavoidable and they came out easily enough with some sanding.
Step 8: Done
I am sorry, I did not get the sanded door pic nor a pic of the door once re-installed but here is the the door stripped, sanded and a coat of clear varathane applied. I choose a water-base coating as it soaked into the wood nicely and dried quickly. I put a couple of coats on to give it a nice protection and was immensely pleased to see how well it turned out. I hope you got a few pointers from this :)