hi fellas,gotta skim a room & the couple scrapped all the skim off the walls as it had blown nearly everywhere. the skim was very thin. the lady said the house was bout 25yrs old. all the walls are solid(browning) & bone dry. should i give em a thirsty drink of water or pva em? i was told pva'ing old browning/bonding walls can create a bad bond between the walls? you fellas will know best?