Yes, I agree with Dan and Parks.
Often, important ships and the first of a class were white painted, especially for photographs. One example was the Oceanic of 1899, dubbed ‘the ship of the century.’
But black was used for hulls at the time when ships were in service, for practical necessity; among other things, corrosion caused by the sea air was much less noticeable on a black hull. Coal also made dirty marks on a white hull and didn’t show-up on a black one.
Photographs of the third sister painted white while serving as a hospital ship demonstrate this; the rust and coal dust show-up obviously. People sometimes refer to Britannic as a ‘rust bucket,’ but if you removed the black paint and camouflage from other liners of the time, they would look just as bad, if not worse.
Later, after oil-firing had been introduced to the liners, it was possible for white-painted hulls to be applied; Mauretania was given a white hull in the early 1930s when she was used for cruising, but there was still the problem of rust.
Best regards,
Mark.