urethane coated interior slate floor

Dear C.:

The urethane coating must be removed and then, either you apply a new layer of the stuff, or you go into a different (and better, IMHO) maintenance program, by applying a good quality stone color enhancer like MB-6. 

May I ask you now to please read and e-sign our Statement of Purpose at: http://www.marblecleaning.org/purpose.htm? J

Ciao and good luck,

Mauri z io Bertoli