Sure have used Insulbrite. Love it for pot holders mitts, and hot pads. I use a layer of Warm and Natural on each side. Just make sure to clean out machine after each use.
I am a teacher and I always instruct new sewers on the benefits of clean machines and new needles for each project.
I remember one older lady coming to class and afterwards she told me she thought the "felt pad" in her bobbin case was supposed to be there! No wonder her first home projects needed remedial repairs.
It only takes a few moments to clean & change a needle-really will improve your sewing.
Love to all and Happy New Year.