Was the statue of David originally painted, or has it always been bare marble?

I did some searching and I can find no evidence that Michelangelo's David was ever painted, or ever intended to be painted. But really the greatest evidence that David wasn't painted is that he isn't painted. Given the kind treatment the work has seen over time and the Renaissance interest in frescos, it would be highly unlikely that David would have lost his paint due to the material ephemerality or conditions faced by classical works, and therefore we can presume that if the paint were lost, someone would had to have removed it. This certainly would have been recorded in one of the many, many histories written about the work, but I can't find any evidence that this was the case.

Remember, in comparison to classical statues, Renaissance art is very, very recent. They didn't see the same conditions that wore away the paint of ancient works. I would be interested to know if Renaissance artists were even aware that the ancients painted their statues; perhaps someone more knowledgable can comment.