I can be literal sometimes, to my cost. The tin of metallic paint said it was fine to be applied by brush and roller and mentioned the need to roll or brush only one way, to keep the metallic bits all flowing in the same direction. It was tricky around hard to reach places, but doable. In talking with a professional painter some time later, after I'd painted the bathroom and a kitchen wall in the said metallic paint, he said that professional painters would never brush or roll metallic paint, as the best finish is obtained by spraying it onto the wall surfaces. Useful information to know…pity it wasn't on the tin.