We use canvas inner covers for a few reasons. They make it easy to take a quick peek in the hive, and are cheap and easy to make. They are light, the lids sit down well, there is less excess wax on the frame top bars, and we rarely need to scrape the inner cover. Ants are also less likely to take up residence on a canvas inner cover. We use 18 oz (#8) canvas – otherwise known as cotton duck.
There will be some shrinkage, so cut it to 1/4″ wider and longer than the length and width of the box.
It is available in the USA online here, in Canada at here, or in Hamilton, Ontario here.
Bees chew through thin canvas so a heavier weight is better. We flip it over periodically when new so the bees thoroughly coat it with propolis. An alternative is a feedbag folded in half.
Please watch the video “Our Equipment” for more details on the inner cover.