Removal of fiberglass wallpaper - How do I proceed?

Dear fellow readers,

we have removed fiberglass wallpaper from the walls in two rooms. In one room the wallpaper came off fairly well, in the other room unfortunately somewhat less well (see pictures). Later, we want to hang wallpaper on these walls (approximately like the one shown in the picture, "Novaboss").

Question about "Good": Do all small residues have to be completely removed before hanging the new wallpaper? Here and there are a few dents that still need to be evened out. I tried to get rid of the small residues with a sander – it works somewhat, but takes forever. Are there other ways to remove the residues?

Question about "Bad": Here the wallpaper was more strongly glued to the wall, so a lot of plaster came off. What is the best way to proceed here? Is it enough to scrape off the yellow residues with a spatula and then roughly plaster over?

Additional question: In another room we still have more fiberglass wallpaper. Should we just leave it on and wallpaper over it? I do not know if it comes off well or badly.

I hope I was able to ask somewhat reasonable questions with my layman’s knowledge and look forward to your answers!

Best regards

Hello,
so on the topic of wallpapering over old wallpaper, I can only say: Don’t do it
We have just renovated/restored a house and in some places the wallpaper was pasted over. Of course, it came off really badly and took forever. Sure, it might be faster now but at some point you will want to wallpaper again and then you will curse that you didn’t remove the wallpaper beforehand
You should make sure that the surface is clean and has no dents, bumps, etc. because you will see all of that later under the new wallpaper, even if the texture supposedly hides a few things.

Hi X_SH5_X,

thank you very much for your quick message.

Regarding leaving the wallpaper on: That's exactly what I thought too. Now put in a bit of work once, but then it's done properly.

Do you have any ideas or suggestions on how I can remove the residue? Just roughly sand it down since it will be replastered anyway?
How to possibly remove fiberglass wallpaper a bit better I have now figured out myself or read up on.

It was a tedious job scraping off the wallpaper. Making it nicely wet helps, but it still remains an annoying, time-consuming task. We then sanded the walls, just like you said. We borrowed a big sander from a buddy and worked on the corners/edges with a small triangular sander.