I don't know that ceiling paint is washable.

We had sherwin and williams ceiling paint up for over 10 years and it looked pretty decent. However, it was not washable--we had a pan catch fire and got smoke all over the ceiling and that did not wash off at all.

We just repained and the painter used pratt and lambert. He said he prefers that ceiling paint.

If you want washable--you could just pay a little more money and use a regular flat washable paint.