In taking apart my old post, I noticed that the column and posts all
had a sheet of copper nailed to the bottom side.
Was this used to prevent rot with the idea being that the natural
corrosion of the copper would cause copper ions to leach into the wood
thereby protecting it with the natural microbacidal effect of copper?
Just curious to understand how they did it in the old days...
Also, since these old column are still in excellent shape, would it
make sense to replace the now corroded sheet with a new one to give it
It probably helped both with the copper ions, as well as protecting the end
grain from being in contact with the wet floor be it wood or concrete,
reducing the tendency to wick water up into the post hastening
deterioration. I would go with what has worked in the past and replace the
copper sheet with new copper.
I've never heard of this particular usage, but they used to put copper
sheeting on the hulls of wooden ships to eliminate (or vastly reduce) the
growth of marine organisms (bottom fouling). Actually, I think they still
use copper-containing paint on ships hulls to this day (or at least until
recently, perhaps....environmental issues??).
Copper flashing is less toxic and stronger than lead flashing,
longer lasting than galvanized steel or aluminum and a century
ago was much cheaper than aluminum.
The original dome of the Yerkes Observatory was covered
with copper and it lasted about a hundred years.
It probably was there to prevent water from wicking up into
the posts and columns. It also could have been there for
termite and carpenter ant protection.
Yes, still done today too. Copper is affordable and very long lasting.
Unlike lead, it doesn't corrode preferentially through pinholes.
Best to fold it over and nail through the sides though. You don't want
to penetrate it.
For longevity measured in centuries in this application, copper is
still the metal of choice.
They make galvanized post bases as well (check your lumber store, they
come prefabricated for 4x4's etc.), but these are usually gone in a
decade or so. A much thinner sheet of copper can last for a hundred
Good economics doesn't look at just the price per pound, but also at
how many pounds you need and how long it'll last....
Several years ago, when copper wasn't nearly so expensive, the
Baltimore subway system had a substantial amount of copper third-rail-
electfication-cable, big honking cables to carry thousands of amps at
800V, stolen from an operating line!!!!!! Everyone is astounded at the
audacity even today!
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