If he is breed to white though it will be white?
If you're talking about breeding him to hens that are pure white, like another White Rock or a White Leghorn, etc, then yes, their offspring should be all white. Breeding him to a dominant white breed like White Leghorn may result in some flecks of color or color leakage showing through in the offspring.
If you're talking about breeding him to hens that are mostly white, like Columbian patterning, then what they produce depends on what genes he could be hiding underneath his white coloring. Most likely his offspring with such a hen will not be pure white, though.