On 8/12/2017 7:17 AM, philo wrote:
I have a old bathtub that never seems to get really clean. I always use
a standard cleanser such as Comet or Ajax. Recently I was advised to try
Bar Keepers Friend. Instead of using an abrasive as it's primary
ingredient it uses a mild acid. Not strong enough to burn you but seems
to clean better.

I've only allowed Bon-ami "polishing" cleanser or Barkeepers Friend to
be in my house to avoid this problem.