@nprofile1q... I didn't use anything underneath, just on top.
And the dissolving paper I got (cheap stuff) is great at dissolving, but not great at printing. It has an adhesive and backing paper, but the adhesive is very weak and it came apart from the backing while going through my laser printer, causing a paper jam. (It actually did print the pattern, but onto a crumpled mess.) I want to get some dissolving paper that's better for printing. Do they make it in single layer without adhesive?