I do use the dishwasher on jars, and I do use them again, and have not had a problem. Thorough wash and high heat dry... confident enough that the jars are good to go. The tobacco on the other hand....well, I've seen the places these fine treats are made and there is no way on earth that the tobacco I'm jarring is as clean as the jars I'm using. Still, I rarely have had a mold problem. Probably comes with the hobby to lose some from time to time.