Frixion Pen, Erasable by Pilot

Here's the erasable ink pen I use for marking many of my designs on paint including the Barn Quilts in the Painted Block of the Month kits.

I use a blow dryer or iron (held about an inch above the mark) to remove any marks when I'm done painting my designs

"Pilot's best-selling rollerball allows you to cleanly write (and mark), erase the ink by friction and rewrite or remark - all with the same pen. Simply rub out your mistakes with the eraser stud and watch the ink disappear as if by magic!"