Hold on to your hats.
An experiment. I’m making hive pillows using old cotton pillow cases. The pillow is full of wood chips and straw. I’ve been toying with these for the past couple of years because moisture quilts — or quilt boxes with upper ventilation — aren’t as convenient as I’d like them to be. They don’t hold in heat well either. My bees in Flatrock, where it’s unusually cold and damp compared to many places in Newfoundland, seem to need all the heat they can get, and moisture quilts, heat-wise, just don’t cut it.
These hive pillows, from what I can tell, work the same as a moisture quilt. I place a ventilation rim over the inner cover. (The inner cover has a screened-over hole in the middle.) I place the pillow inside the rim, over the inner cover. (D.E. Hive beekeepers might call the ventilation rim something else, but it’s essentially a shallow-sized rim with screened-over holes drilled in the sides.) Then I put the top on.

The result is essentially a ventilated quilt box. Whereas moisture and heat normally pass through the porous bottom of a moisture quilt — where much of the heat is lost — this is the same except it has a solid inner cover to contain the heat better. The pillow helps keep the heat in too.
Judging mostly from last winter, I haven’t had any problems with this set up. But I need more data.
The only concern I have is the cotton pillow case. I made the hive pillows from burlap before, but old pillow cases are cheaper and easier to make because there’s nothing to make — they’re already pillows. I just staple them together on one end.
Will the cotton get soaking wet with moisture? Cotton is not exactly a wicking material. So I don’t know. It could be bad news.
I’ll know in a few months because a wet east coast Newfoundland winter is on the way — with lots of rain and wind. And whoever says most of the moisture inside a hive comes strictly from the bees hasn’t had to keep bees in my local climate. Wind can blow moisture, in the form of thick cold fog and rain, right into hives. It definitely happens.
If the cotton pillow cases get wet, too wet, I’ll remove them and leave the ventilation rims to do their magic of keeping the hive ventilated and dry.
The only problem with cotton is mold. Fungi love cotton & with the excess moisture coming out of the inner cover, you may be constructing a middle school science experiment (like some of the things growing in bowls the back of my refrigerator) Good luck & watch it carefully. Moist mold can’t be too beneficial to bees in the winter.
Yeah, this could be a really bad idea. The burlap pillows from last year are still holding up with no signs of mould. I’ll leave these cotton pillows on for a while, but I’ll pull them if I see any signs of mould. In the meantime, I’m going hunt down more burlap to make more pillows. They much more convenient for me than moisture quilts or qult boxes.