I’m constantly reminding new beekeepers that unpainted galvanized lids get very hot. In this video I measured the difference in the middle of an 80degF day. The painted lid was 20 degF hotter. However the unpainted galvanized lid was a further 20degF hotter.
Hi Jeff, you might want edit this post and add the link to your video. Looking forward to seeing it. Cheers Rod
Thank you Rod, it might be a sign of old age, I think I did that once before, I know I bought a nuc home the other day & forgot to open the entrance up. I remembered the next morning at about 5 o’clock. Lucky none suffocated. I had 6 frames of bees & brood in a 10 frame box. That might have saved them.
That’s one of the reasons I have 50mm of PIR insulation permanently in my wooden roofs
I do a fair bit of service work on roofs and apart from the glare white ones are definitely the coolest. I constantly wonder why people like dark coloured roofs as they are nightmarish on a hot day inside and out. I’m not looking forward to summer roof work. 
I would have thought insulation in the top of a hive, especially a migratory lid with the extra room, would be beneficial for the bees hot and cold however I rarely see it. :don’t know:
Oh and @JeffH, why Fahrenheit?
Age ? 
It’s taken me ages to do centigrade and kilograms but still measure car travel in miles. I run in kilometres though except marathons which are in miles. Daft
Hi @Dee & @skeggley, it’s probably the age thing. My abc to xyz of bee culture talks in degF, as does my other beekeeping books. I always talked in fathoms when out fishing while new comers always seem to talk in meters. I use the thermometer that’s in this video while de-crystallizing honey. I always look at the F. side.
Jeff, interested to know which edition you have?
Oh Skegs, I’m still nostalgic for kroner, francs, pounds, marks, lira & dinars! Leave us daft old fools to our good old days 
Hi Sam, 1978 edition. Would you believe it was given to me, otherwise it was destined for the scrap bin.