[Jpfbeek]

I made up some hive wraps out of reflectix bubble wrap insulation. I figured the reflective surface on the inside would be helpful but I'm worried about losing solar heat from the reflection. Should I find some way to blacken the outside? What's a good cheap way of doing that which will stick to the insulation and not wash off in the elements? I thought about just getting some cheap spray paint and giving them a couple coats.

 

[Saltybee]

Hard to respond, not knowing location.
Doubt it will make much difference. Heat the outside does not mean it will carry thru the bubbles , past the inner foil and to the hive. Good wind break though, I would think. The sun may hit three sides but it will only really work hard on the South side in the dead of winter.

 

[crofter]

Solar gain issues are complicated. Conditions that improve solar gain for the hours of sunshine are exactly the same as those that increase thermal heat radiation away from the hive during all the hours when the sun is not shining.

It could be an informative exercise if someone with internal temperatue logging did a comparison on two similar colonies, one with a shiny surface and the other a solar receptive color. my feeling is it would be inconsequential overall.

There are spray cans of flat black flexible paint that I have seen recommended for solar gain surfaces for rooftop water heating panels.

 

[Arnie]

No.
If you have killed the mites and your hives are pretty heavy (top brood box full of honey) you should not even need to wrap them.
I see you are in central Indiana, zone 6.

I'm in zone 5.
I give them a little ventilation by propping the outer cover up about a quarter inch. Put a few pennies on the frame of your inner cover. 3 maybe. Reduce bottom entrance.
Replace the telescoping cover. Done.

Keep it simple.