The absolute world leader in solid surface coatings Concrete etc, is GuardIt Solutions. The only non solvent, water based, food grade sealer in the world and out performs anything else. The only thing that gets close is a German product but it is a 2pk, difficult to apply, very dependant on thermal and moisture conditions and limited application once mixed. GuardIt is easy and safe for a child to apply.
If you are interested in further details send me a PM as my family owns the global patents for it.