Just an FYI regarding thermal paper and highlighter pens. At a former job some of the staff were printing some free product vouchers. On each they highlighted

Just an FYI regarding thermal paper and highlighter pens. At a former job some of the staff were printing some free product vouchers. On each they highlighted certain data to make it easy to spot. Well they soon found out that a highlighter on thermal paper will erase what is highlighted. It takes some time but it does a great job of erasing it. I don't know how or what the chemical process is but it does work, or fail, whatever your goal was I guess.