I had the ceilings in my kitchen and dining room plastered about 10 days ago (they were artexed before). I've now used plaster sealer on them both and then painted them with white emulsion. However, both ceilings have now had 3 coats and still look patchy. Where am I going wrong? Im using a roller but would it be better to use a brush? I'm trying to get it all finished by the weekend cos I'm having a new kitchen fitted then.