I've tried using both International water based Radiator Paint and ICI's Dulux "Realife Tough Satin" in brilliant white. Both are reassuringly white and delightfully smell free, but dry before the brush marks have disappeaed.
I have no problem with brush marks in either Gloss or Satin (my preference) paint finishes. I guess that the problem with water based paints is that they dry before surface tension has enough time to force an even surface.
I guess that only painting during rainstorms or when boiling a kettle might help, but I'd be grateful for other suggestions. I realise that a foam roller would probably give a better finish on a flat surface, but radiators and other items I want to paint, are far from flat.
Will I have problems if I rub down the water based paint and recoat it with conventional Satinwood? (I'm thinking of the sort of disasters you get if you try and paint Finnegan's Hammerite over oil based paint:)