I agree that Guardz is wonderful for a seal coat on damaged drywall. I do not agree that it seals wallpaper glue all that well. I stripped a bathroom, had lots of wall damage so I knew I would need to use the Guardz. The label says that it will seal the paste, so I did not try to get ALL the glue off, but it did not. Since I was doing a venetian plaster finish on the walls, I knew I did not need the surface to be perfectly smooth. After priming with Guardz the plaster bubbled up on me. In the future I will always use an oil primer to seal in any wallpaper glue that just did not want to come off. Just my two cents.
m1951- All of us who recommend Gardz say to a person to remove the paste first. If you are doing what you did, I would have used 2 coats .
But I have also seen oil fail both at sealing paste and sealing damages wallboard. It depends on how completely and thickly it has been covered.