I'm removing wallpaper that has a layer of paint underneath. Currently, I'm using a scoring tool then a steamer to remove the different layers. As you can imagine this is a slow process. Would it be advantageous to use chemicals before I use the steamer?
I have witnessed surprising results by covering wallpaper with a thick layer of wet joint compound, right out of the 5 gal bucket. We call it "mud" in my region. Let it sit a while, and the moisture and weight will almost remove the wallpaper by itself. Try it yourself on a small area and see if it will work in your application.
we removed an entire house worth of wallpaper when we bought this house. some of it was 1 layer (dining room), some of it was multiple layers (7 in the bedrooms, no, really, there were 7 layers!) and 1 layer in the kitchen that was over drywall (the rest were over plaster walls)
chemicals did no better than a streamer with a touch of hand soap in the water
plaster walls - wet the wallpaper with a water bottle - dont soak it that its running down the wall but get it moist - then use the steamer and a 4 inch putty knife and scrape it off
hold the steamer to the wall, about 20-30 seconds - it should begin to peal - scrape it off and move on. once you get the hang of it, you can scrape off 1 section while steaming another.
this is a very hot process - if you have air conditioning, use it.
drywall walls - you need to be much much more careful; the paper backing on the drywall can peal with the steamer also. hopefully, the drywall was primed before they put the wallpaper on - ours wasen't. same process, but be much more careful; opting to pull the paper up by hand when you can and only use the steamer when you need it.
if you do wet the drywall backing, you'll need to cut the bubble on the paper the steamer produces out with a utility knife. prime it, plaster in the gap the cutout made and prime and paint (or whatever your final coat is).
keep a dust pan and broom close by and cover the floors if you can / plan to salvage them. the wet glue left on the wallpaper you just let fall to the floor after scraping it off the wall will stick to hard wood floors and probably stain carpet.