Marie, You can use Thompsons water sealer. It is not the same as concrete sealer. I use craft acrylic paint, wood stain and a couple of products ( stain, dye-stain and paint) from Smith Paints in Harrisburg, Pennsylvania that are for concrete statuary. I don't seal my leaf castings or planters. Billie

One question. . . did I see something mentioned in here that Thompsons said not to use their sealer on anything to be used as a bird bath because it releases something harmful to the birds when under water? (Not that you are planning on using your leaf as a bird bath. . .just in case someone else is.)

I've just read so much online lately I can't remember if this is what I did read.