Winger and Jason:

My suggestion, not based on experience, but on chemistry and
toxicology logic, is the use of sodium silicate ("waterglass")
for sealing.  Any type of polymeric sealer is likely to have
small amounts of unreacted monomers and possibly plasticizers
that are likely to leach into the water and be toxic to the
birds.

Waterglass is used for sealing concrete and cement (Wikipedia,
under "sodium silicate").  It is water soluble, but when it comes
into contact with the calcium matrix in cementitious materials it
reacts and "connects" to the matrix, sealing it.  It is much less
toxic than most organic polymer ingredients, but residual amounts
will be an alkaline irritant to the birds, just like uncured
concrete.

You apply it as a thick liquid.  I would allow it to cure for
about a week ( in the sun would be good), then rinse out the
birdbath several times, letting it sit overnight but covered to
keep the birds away, before filling it for the birds.  This will
reduce the alkalinity to a minimum by leaching away unreacted
sodium silicate.

One source is online through eBay.  Try this -
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5678077215&cat
egory=1467

Bill Ellis
Eldersburg
Carroll County


-----Original Message-----
From: Maryland Birds & Birding
[mailto:[log in to unmask]]On
Behalf Of Winger and June West
Sent: Monday, June 19, 2006 5:33 PM
To: 
Subject: [MDOSPREY] Fw: [MDOSPREY] RFI--sealing concrete birdbath


I too have a similar problem and I imagine there are others out
there who do
also.  Can you reply on line?  Thanks.

Winger West
Millersville, MD


----- Original Message -----
From: "Jason Waanders" <>
To: <>
Sent: Monday, June 19, 2006 2:50 PM
Subject: [MDOSPREY] RFI--sealing concrete birdbath


Forgive the slightly unusual topic, but I'm wondering if anyone
on the li
st
has any expertise in how to safely seal an existing in-ground
concrete

birdbath.  I made it out of Sakrete sand mix, and it's been very
popular

with the birds, but it's a bit too porous and loses water due to
seepage.

I probably should have built it with a liner, but now I'm trying
to figur
e
out a way to seal it without starting over.

Sakrete makes a "cure and seal" product, which is a water-based
acrylic

that would probably do an adequate job.  But the manufacturer was
unable
to
advise me as to whether or not this would be safe enough for the
birds

(i.e. will it leach into standing water, and if so, would it be
toxic?).
 I
know there is a safe epoxy-based product out there called Pond
Armor, but

it's very expensive.

I'd appreciate any advice anyone has!  Off-list may be more
appropriate f
or
this one.

Jason Waanders
NW DC
jwaandersATstarpower.net