Here in Australia most boxes are painted white.  There was research carried
out in Australia many years ago which showed that white was better than darker
colours because it was not as hot inside the hive.  Therefore the bees did not
have to spent unnecessary time cooling the hive.  This research was carried
out on empty boxes, with bottoms and lids, placed out in the sun.  With
temperatures which can reach into the low 40's celsius any help the bees can
get is, I am sure, appreciated.
 
Some used aluminium paint because it stood up to heat from grassfires better
than white. However there are several good heat resistant white paints.
 
Linseed oil was used in the past but you cannot get the old formulations
nowadays.  One of the reasons why linseed oil has not been commonly used in
recent years in Australia is that linseed oil is one of the perfect cultures
to grow mould on.  Here the boxes covered in linseed oil would become black.
This then caused the hive to become hotter than it should as the black
absorbed heat.
 
As a lot of beekeepers treat their boxes with copper naphthenate, to stop rot,
some add linseed oil to the copper naphthenate to stop the timber drying out
in the low humidity areas, such as the yapunyah country.  Here the humidity is
low and the timber will dry and so the linseed oil "conditions" the timber.
The maximum amount of linseed oil that can be added is around 15% of the
total volume.  Over this, the linseed oil interferes with the copper
naphthenate penetrating the timber.
 
Even our Oz lids have white painted or colorbond (trade
description) metal on them to reflect heat.  It is amazing how cooler these
are on the surface compared to straight galvanised metal.
 
 
Trevor Weatherhead
AUSTRALIA