DIY Doctor UK DIY Forums

Hi everyone, I'm busy modernising a 120 year old property. I've begun to remove the old wallpaper from the walls and have used a product called smoothover from polycell with fantastic results, however, I have discovered on some walls a base layer of varnished paper. This will not budge. I've tried everything. I tried using the smoothover over this area but it doesn't dry properly or adhere well to the wall. Is there a product I can use to seal/prime the varnished area before using the smoothover or similar finishing coat?

I have never used smoothover, is it a paint or plaster product. I'm not a fan of plastering over wallpaper is the weight of plaster could just pull the paper from the wall. PVA is a good a seal than must.
KB