I think a stain would hold up if you were able to coat it with a clear sealant. Something like Kure-n-Seal maybe?
WARNINGIf you have installed foam insulation around the perimeter of your slab (typical for a Pex radiant heat installation), Kure-n-seal will melt it down like ice cream on a 98 degree day. - Fortunately, we performed this test moments before we used a sprayer to apply KnS to our newly poured slab with the foam perimeter. Just as fortunate, I was mindful enough to prepare another contingent application method by bringing a paint roller to the jobsite....Justin Case. Whew!!! Even the roller requires great care during application. Stay at least 2" + from the insulation and don't lay it on dripping wet when this close. The KnS can easily run over to the melt zone.
