I purchased a house that was built in 1952. The kitchen had the usual 8 layers of semi-disintegrating paint and wallpaper which I resolved to remove. I assumed the walls were plaster considering the age of the house. However, though the first layer of wallpaper came off fine, the rest of the layers aren't. As it turns out, the interior walls are not plaster or drywall, but instead appear to be made of some kind of cardboard. I am using a paper tiger and various solutions (dif, vinegar and water, fabric softner etc), but when I score the paper, all the solutions soak into the cardboard and don't loosen the paper, when I scrape, the cardboard becomes rough and uneven and I don't think it will be sandable. I have had an army of contractors in to look at this and they say everything from using a skim coat to laying drywall over the top of this, to ripping out the walls. Most want to patch it up and paint over the lower layers of wallpaper and avoid disturbing the cardboard. I really think ripping the walls out sounds excessive, but I don't want to be cursing myself in 5 years.