Randy wrote

> A point not always made clear in this discussion is whether the hot-dipped
> or copper-treated are then painted. Old research from Forest Products
> Laboratory demonstrated that painted pine wood lasts many years longer if
> treated with a water-repellent preservative (WRP) prior to painting. 
> Simple
> paint over raw pine has a very short life, especially over the end grain.
> Rot generally starts there.

If you can keep the moisture out of timber then it will not decay (rot). 
Paint usually has the problem with bee boxes in that the paint is broken by 
use of a hive tool and water can get in.  If you can keep the moisture 
content of the timber below 20% then you will not get decay.  This is why 
some climates are not conducive to decaying timber as the equilibrium 
moisture content (EMC) of the air is below 20%.  This is not to be confused 
with relative humidity.  You can have high temperatures and high humidity 
but a low EMC.  There are charts out to do the calculations.

Water repellents are just that and by keeping the water out, stop decay. 
However I think it is in the Kalins and Detroy paper where they used tri 
butyl tin oxide (TBTO), which is a common water repellent, and they got 
residues in the honey.  So I would be wary of any other water repellents.

I paint the inside of my boxes.  These have been treated with copper 
naphthenate.  I do this to reduce the possibility of any copper residue in 
the honey.  Kalins and Detroy used a copper naphthenate solution which is 
about 10 times stronger than I use.  They obtained elevated levels of copper 
in the honey and the inside of their boxes were not treated.

Many years ago there was a survey done of honey for residues in Australia by 
Graham Kleinschmidt.  He did not find any elevated levels of copper in honey 
from hives that had been treated with copper naphthenate and painted inside. 
Not sure if there were boxes that had not been painted on the inside.

Trevor Weatherhead
AUSTRALIA 

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