Marjorie,
Bentonite, a clay, has been used to seal earth dams, among other uses; it
should work to seal the birdbath and should not be harmful to birds.
Jack
Thompson Conservation Lab
Portland, OR
[log in to unmask]
 
 
On Mon, 30 May 1994, Marjorie W. Cleveland wrote:
 
> The following question came from another bulletin board, but the
> person asking for information received no response.
> He has a leaky concrete birdbath, and is looking for advice on
> how to seal the leakssafely, without poisoning the birds that
> drink from the birdbath.
> Anyone have helpful suggestions?
>