I applied 3 coats of undiluted tung oil on my new Flow Hive in Dec last year. The sides are still ok but the whole roof is black all ready. Is this normal?
The black is mold growing on the roof. I would try cleaning vinegar and a finger nail brush to remove it, but it will be an ongoing issue. The alternative will be to paint the roof white with at least two coats of a water based acrylic paint brushed on fairly thickly and it won’t need repainting for 4 or 5 years.
Don’t paint the roof with out killing the mold first.
Yes, it is normal. Not desirable, but normal. I am going to sand mine this winter, and use some wood bleach if needed (oxalic acid) to get rid of the black mildew. I talked with a sailing boat wood finisher, and she showed me how to do that. The black stuff isn’t toxic, but I don’t like it. I will probably reseal the roof with marine spar varnish, as I live very close to the ocean. I intend to put flashing underneath it too, just in case we get any rain this winter.
I painted mine a light blue to match my hive base. No mold issues. I hope this helps.
totally normal- if you get a lot of summer sun it will go grey during summer. We ended up painting or wax dipping the roofs as they cop so much more weather than the rest of the hive.
This can be normal in humid/wet environments, and you may prefer to paint with some waterproof paint or sealant to keep your roof waterproof and prevent mould.