I have two TBH’s. One had a large colony at the end of last year, one a small one. I just opened the small one to feed it (probably a meddling mistake but I was very alarmed how light it was). I observed that despite its excellent sealing there was no mould or condensation inside. I didn’t need to feed the other TBH, which is almost too heavy to lift, but I opened its mesh floor for ventilation. I noticed, as I have before, that a sticky liquid was on the board which had been pressed up against its mesh floor.
The question is, why should one colony have (condensation?) and the other not? And should I ventilate it more? The TBH’s both have more than one inch thick wooden walls and plenty of insulation in the roof – they are better insulated than most conventional hives. The sealing on the large colony, which had this liquid, is not perfect, it has minor leaks at the base of the hive (around the mesh).