Recently, I’ve seen several of these Butter keepers or Butter Crocks advertised as a way to keep butter both unspoiled and spreadable. Do these things work? If so, how? I’d think that the microbes that spoil the butter would grow in the water too. It may make an air tight seal that lessens the accessablity of the microbes to the butter, but when the butter is out of the water being used, there are microbes around to get into the crock for later spoilage.
So, how does this work?