Yes, it is very important to get all of the finish off if you're are planning to stain it. Oak has a lot of "open grain" in which the finish sits, if you don't get it all out, the stain won't absorb in those spots and will give you mottled finish. You will probably need to do use a combination of a chemical stripper and sanding to do it right. You may be able to do it all with sanding if it doesn't have a lot of decorative work or carving on it. Conditioner is typically used on softwoods that don't absorb stain evenly and is usually not needed on oak. You might also look into using a gel stain which sits more on the surface and isn't as dependent on sinking into the wood. You might want to do some experimentation on an inconspicuous area of the door after you strip it.

Thanks ventupete :)

I ended up getting a gel stain - the paint store guy said it sinks into the wood just as deeply as regular stain; we'll see. At least I can test it & return it if I don't like it.

I found some stripper called "Safe Strip" - non toxic, safe, yadda yadda - but at $85 for a gallon I decided to try the elbow grease approach first. The door has some curves & nooks & crannies, but no elaborate carving, so hopefully the sanding will do the job.

Gel stain does NOT sink into the wood as deeply as a wiping stain. That is why it is gelled, so that it does not and thus does not cause blotching. It sounds like your "paint store guy" is the typical knows paint but knows cocca about wood finishing.

Check back in after you've sanded and tell is if you are of the same opinion.

heh. I didn't have much faith in paintstoreguy as it was (so-something, bit of attitude) but at least they let you return things!

Actually, I talked to someone else at the same store yesterday (older, seemingly more knowledgable, but still.....) & talked to people at the hardware store as well.

And then I remembered The Garden Web. I haven't been in for awhile (hung out a LOT at the Kitchen Forum last year - The Year Of The Kitchen Remodel). Anyway, yes, I listen more attentively to the voices here than I do to the voices of the 3D people who work in stores :D

I'll be sanding & staining tomorrow; will check back with results.

And thanks bobs - I've never used a gel stain before, but it just seems logical that anything gel-based won't penetrate as much as something more liquid. It also makes sense that it might serve my purposes better, given the oak.

After about half an hour of sanding, the chemical stripping option was starting to look REAL good, so that's what I did.

I tested some of the gel stain before I stripped (on a well-sanded area), & although the stripper removed most of the stain, there was still a noticeable stain left that had penetrated the wood.

It's been a lot of work, even with using the stripper, but I'm happy with the progress so far. Still deciding which finish to use - Marine Spar Varnish or Base Paint.