Waterproofing cement

To the real estate editor:

Some time ago there was an item in the Ask a Builder column which mentioned a claylike material which could be applied to the exterior of a concrete area to form a waterproof surface.

Can you tell me what it is and where it can be obtained? Sarkis Kurkjian West Newbury, Mass.

Bentonite is the name of the product. See the definition in an unabridged dictionary.

I suggest you rely on interior waterproofing instead of bentonite which is marginal. Try Sealwall Products Inc., 36300 Lakeland Boulevard, Eastlake, Ohio 44094. Phone: (216) 951-3445. F. M. H.