Need help solving tiny and larger blisters on wall

[zenonithus]

Hey all, I'm painting my room walls and getting tiny blisters on many areas of one wall. The other 3 walls seem to be free of any blisters.
I originally wallpapered the walls then decided to take the paper off. It left residue paster so tried to clean that off. Then someone said to pva 50% water to seal in the left over paste. Obviously big mistake so I sanded them down and applied gardz primer sealer. Them gave a few coats of contractor emulsion white as under coat. Not the best stuff but too late. So you can see I have had a nightmare finishing this room ☹
So back to the blisters, I treated this wall exactly the same as the others. I noticed the blistering when wet paint is applied as it appears flat when dry. It blistered more when I applied the vinyle emulsion over the contractor undercoat. Could it be the original paint on the wall reacting to the dampness of the paint?

 

[Nige F]

Looks like that's whats happening maybe you got so much contract emulsion - it has no vinyl in it - built up that the final vinyl is "livening " up the contract paint . PVA should carry a warning on the tin. As it's one wall you could sand the lot back and Zin it again

 

[zenonithus]

Hey Nige, yeah I can see that being the reason, though I applied the exact amount of CE to the other walls, exactly the same process so I'm confused with it.

I think I have enough experience to know exactly what to not do for the next rooms I noticed the blister areas are taking longer to dry out. I'm going to try sanding the blister bits only and just go over them with the top coat vinyl emulsion rather than undercoating with the contractor stuff.