Comparison of two set of data

in my industry, we are allowed to run our equipment for 12 hours before cleaning. we did a capability study to see the effects on the quality of the finished product if we run the equipment for additional 6 hours. samples were collected hours from 0-12 and 12-18 hour. what would be the best statistical method to compare the results of first 12 hours with the following 6 hours?
p.s. I have access to Minitab.

Thank you