I'm painting a living room. The landlord has use zinsser bin on the wall between the ceiling and the wall and down the side where the corners are. I've opened the tin that they've used and it's quite yellow so I'm assuming it is off. Even when it's been mixed it is quite yellow. I've tried painting over with emulsion but it keeps coming through the yellow tinge. Would it be worth trying Zinsser guard to cover over the the BIN or should I buy a new tin of zinsser bin and cover it that way. I'm attached some photos and would appreciate some help thank you so much.