Alternative to glazing ceramic tiles

Unfortunately, we have been experiencing many issues with our very OLD kiln. I had a few classes left that did not get a chance to use the ceramic glaze and I didn't want to use the kiln anymore than I already had to.  I decided to try painting them with a watercolor resist method. The students LOVE Crayola construction paper crayons because they are really bright like chalk (without the mess) so I had them color their tiles first and paint watercolor paint on top! They look fabulous!  Parents: I told the students it would be a nice touch  to spray them at home with a protective glossy varnish spray to bring out the color and give it a layer of protection!