I am refinishing wood kitchen cabinets, about 1950-ish. I started out with Citistrip and then changed to methylene semi-paste. I thought one bottle of Cit. was junk, as it would not soften the finish, so I switched (not mixing the two, of course). Even with the methylene, some of the finish is barely softened...seems to be the base coat, mainly inside of cab doors. This is bizarre, as I've done tons of refinishing and never encountered this. This tough finish doesn't soften much, even after leaving meth. stripper on for an hour or more. I lift off as much of the stripper as I can with a wide plastic scraper so I can reuse it. This finish - some kind of varnish stain?? - is still in place and requires scraping hard with a metal scraper. If I don't scrape it off ASAP after removing the stripper, it doesn't want to come off. Scraping it right away yields a pile of fluffy stuff that looks kind of like cellulose insulation - almost dry and kind of powdery.
This house was built like a fortress, may have been owner built, and cabinets are kind of different...plain, thickish veneer over wood strips...can't imagine what finish was used. Seems like some doors have another finish??!