Cantera

Q.We have cantera outside out house, which has become stained, mostly greenish/blackish...possibly mold? A contractor gave it a re-surfacing, but the stains remain, and appear to be quite deep...any suggestions?

A.Cantera is a volcanic quartz product that has a porous texture.You will need to do a little research here to solve your problem.Call the folks that sell the cantera stone at 602-971-6611.They will be able to help you.

Because of the mineral composition of this stone it may be prone to etching.You will probably need a mildecide to kill the little buggers.

But you must be careful what products you use as you could damage the stone.TESTING is important unless you can find a stone pro who knows cantera like the back of his hand.

Stu Rosen