Re: Birdbath question
- To: s*@MAELSTROM.STJOHNS.EDU
- Subject: Re: [SG] Birdbath question
- From: M* T*
- Date: Wed, 15 Nov 2000 03:01:05 -0500
Well, Bobbi, we've got a concrete bird bath that has been outside
with water in it for well over 30 years. Due to getting dropped, the
base is much shorter than originally intended and it does have a
slight crack and does not sit exactly level, but it holds water just
fine. No sealer, just algae:-) This birdbath has survived winters
with temps as low as 5F to my certain knowledge...
I have cracked ice out of it, lifted ice out of it and left ice in it
and poured hot water on the ice...doesn't faze it.
From a technical standpoint, I think the shallow sides do not allow
ice to create enough pressure when it expands to crack the concrete.
If, for instance, the birdbath is brim full of water which freezes,
the ice will simply expand to be taller than the sides of the
birdbath and not be able to push on them, if you see what I mean.
If the concrete is not porous in the first place (which it really
can't be and hold water), then no ice can form within the concrete
matrix and do damage. If it is porous, as clay is, then water gets
into the material itself and upon freezing, expands and can exert
enough pressure to crack a brittle material (low fired clay pots, for
instance).
So right those baths and fill them..the birds will thank you as water
is even more important to them in winter than in summer. If you are
worried about ice, get one of those low voltage electric bird bath
heaters to keep it from forming - the birds will also appreciate
that:-)
Marge Talt, zone 7 Maryland
mtalt@clark.net
Editor: Gardening in Shade
-----------------------------------------------
Current Article: Clearing Woods - Part 3 - More Vines
http://www.suite101.com/welcome.cfm/shade_gardening
------------------------------------------------
Complete Index of Articles by Category and Date
http://mtalt.hort.net/article-index.html
------------------------------------------------
All Suite101.com garden topics :
http://www.suite101.com/topics.cfm/635
----------
> From: Bobbi Diehl <diehlr@INDIANA.EDU>
> Date: Tuesday, November 14, 2000 6:59 PM
>
> Hi folks,
>
> To settle a domestic dispute, would there be any experts out there
who
> could knowledgeably discuss the potential danger to concrete
birdbaths,
> filled to the brim with water, during a period of 25 degree lows
and 40
> degree highs? My husband insists that because of the concave shape
the
> birdbaths can be safely left to freeze and thaw over the winter.
Physics
> and all that. I insist that the birdbaths will be damaged and need
to be
> replaced next year. Can anyone resolve this for us?
>
> By the way, the birdbaths are now safely emptied and on their
sides, but
> Himself is not a Happy Camper.
>
> Bobbi Diehl
> Bloomington, IN
> zone 5/6
