"It's in there for awhile," said Hart, who is naturally blond with a thin blond beard. "Just me and J.J. We'll start a trend. We'll get hot and everybody else will do it."
Hardy, who normally has brown hair and a goatee, said the idea for the beauty makeover was born on Saturday.
"We were on the bus back to the hotel and guys were talking about doing something, like dye our hair or shave our heads, to shake things up," Hardy said. "And we decided to go black."
Hardy and Hart were getting ribbed, and they were giving it right back. They tried to convince reliever Seth McClung to join the trend.
"That's easy for you to say, Mr. Presley," McClung shot back at Hart.
"I think everybody knows that I don't know how much hair I have left," said McClung, who's thinning a bit on top and only wears a cap during business hours. "I don't know if this is my last layer here. I don't think I can do it. I'll grow my goatee out and paint it black like they did."
"I don't want to cut my hair," McClung added as if to defend his decision to stay red on the head. "I want to grow it out and save it for later. Who knows how long it will last?"
Manager Ken Macha was amused by the actions of Hart and Hardy, but said he's not getting involved. At least not for now.
"I opened my mouth once in Oakland," said Macha, who managed the A's from 2003-06. "I said if the team wins five games in a row, I would shave my hair. They did. I've got to watch what I say from now on. Chris Singleton brought the shears out. If I did that here, they would choose a guy.
"If you see me come in with black hair, you know we're in trouble," said Macha, whose hair is a mix of silver and white. "Actually it was refreshing to take a shower and have no hair. I can't tell you how long it took to grow back."