Hi Ed..
 
Over here on single walled hives we would use 100% creosote or "Cupranol".
Some I know mix creosote and old engine oil but I think that there may
be poisons in this oil.
If you decide to paint it is recommended in the books not to use gloss
paints as this prevents the wood from breathing and encourages condensation
inside the hive.
Color does not really matter but it would be wise to use the natural wood
shade or a light color if you get hotish weather so as to prevent overheating.
 
Just make sure that what ever you use does not contain pesticides!
 
Philip Earle
Northern Ireland.
BCG0311 @ V2.QUB.AC.UK