I do test a new product before going forward on a major product. DH told me a long time ago to take the time to test. You can replace a small block quilted and tested much easier than a finished quilt. I have had no problems with the heat disappearing ink pens I use. A few problems with chalk residues and quilting pencils leave the most behind. I do know that others have had problems with the heat disappearing pens but I have not so for now that is my experience. One thing I must get better at is pre-washing fabrics.