How strong? I recoiled when I opened the bag. When I put the bag in my car it filled the vehicle with an overpowering odor my daughter commented on. Put the balls in a laundry basket and kept them outside to let the air dry the paint and let off some fumes, but hasn't helped much. That said, the balls are in decent shape for the price. I'd say 25-30% are playable on a course. I use the rest for practice. It's clear few of these balls were originally yellow. They are painted over, and I just hope it's not unsafe paint that will make me a lead poisoning fatality. I certainly wouldn't put my lips to any of them, even after sinking a long birdie putt.