White wash plastered wall

totally agree with dale carpentry but as long as the white wash is of a correct mix and dont cause issues for the painter plasterers dont normally do the white wash so in my opinion its slightly suspect

It sounds like your plasterer has really gone the extra mile for you as this is normally the first thing a decorator would do. This whitewash or mist coat is normally watered down emulsion. Not only does it show up any imperfections (it's quite normal on freshly plastered walls to have the odd little dent or knock) but it also helps the top coats of paint to adhere to the new plaster.

I find it a bit odd. Never known plasterer do this. I would be asking if you had been charged extra for this, Labour and materials. As it could be a way of making extra wages for the job. If this isn't the case then I would think he's not confident in his work to just leave it to be painted. A mist coat (watered down emulsion) is normally applied by a decorator. But a decent decorator goes around and fills any knocks or imperfections first. Then checks after its been painted by shining a light close to the wall and looking down it. Then he would touch up any areas he's missed. If you're happy with the finish when it's fully painted then at least he's done his job as a plasterer. But if you have been charged for this extra just make it clear next time that you will be painting it.