Charcoal floor grout

[yeronga]

I have tiled and grouted a small conservatory with charcoal grout. (bout 2 weeks) The grout is drying out grey on most of floor but almost black under radiator (comes on with heating but set low).The conservatory has been quite cold and not much drying.BAL superflex charcoal was used. Any ideas ?

 

[Andy Allen]

sure you havnt got a leak, when the grout is wet it will go black..