Hello all!

We recently ripped down our basement drop ceiling and after much debate decided to paint our ceiling beams white. We purchased a paint sprayer to do this (we first attempted to do this task by hand rolling which took FOREVER)... so far we have done 4-5 coats on a heavy spray setting and we still can not get the beams to fully coat. We did use a cheaper flat white paint but have done so many coats! It still looks so blotchy. We are thinking it must have been sap from the beams? Our house was built in 1950 so not sure if the age is a factor. Does anyone have any suggestions or recommendations on how to get a full coverage? Even when hand rolling it still poked through but not as much. Thanks in advance!!