R-Value comparison for thin film insulator that is less than 1'' This topic contains 1 reply, has 2 voices, and was last updated by King 4 years ago. Author Posts October 10, 2014 at 3:03 am #3295 needtoknow0230Participant Points: 18 I’m trying to give a comparative R-Value to a thin film insulation that is 12-20 mils (300-500 microns). Could it be done? is there a formula to estimate that? November 28, 2014 at 2:52 pm #3314 KingParticipant Points: 96 I have answered it here: http://mechteacher.com/forums/topic/welcome-to-the-thermal-engineering-forum/#post-3312 Author Posts You must be logged in to reply to this topic.