They are great, but if the item you are marking gets cold, the marks will come back. Ironing them will make them go away again. I am having that problem on a cross stitch Quaker Ball and I decided to mark up the fabric where each motif was going and the mistakes I made in marking came back even after ironing them when I left it in my car over the winter. Make sure you can wash the item if the marks are in an area that won't be covered.