Cell size affects water content

I started taking down my bees to small cell size 15 years ago. 10 years ago I had combs with 4.9 mm, 5.1 mm and 5.4 mm cell size in the supers. At one time I did some measurements of moisture content in honey from the capped cells in supers.

The supers were square sized for 12-frame Shallows. Single walled wood, not very thick to keep the weight down. Almost all my supers are like that. I measured moisture content in honey from cells close to the top of the frame, in the middle. When comparing the different cell sizes in the same box it was done from two frames, comb sides next to each other.

What I found then was that the moisture content in the center of the box was 1% lower than from the outer combs. This was the case when all combs in the super had the same cell size. I speculated that this was due, at least partly, to the fact that the uninsulated walls of the super made the temperature vary more in the super during day and night, especially close to the walls. During nights water drops could well be formed on the outer frames. And the honey could thus take up more moisture.

The moisture content was then 1% lower in cell size 5.1 than in 5.4. And it was 1% lower in 4.9 compared to 5.1.

The moisture content was so low in the smaller cell sizes that I became braver to harvest combs that were not fully capped. I started harvesting whole boxes even if the outer combs was not fully covered or even 2/3 covered. Sometimes outer combs were and also are today only capped at the top. Shallow frames are low, 137 mm, so it will not be as large area of ​​non-capped honey compared to a higher frame where only uppermost part of the honey is covered.

Water content in my honey is usually around 16-17%, rarely above 18%, sometimes below 16%. Before I used small cell size, moisture content was often around 18%, even though I tried to harvest only capped honey.

Project with plastic frames and insulated boxes

This year (preparations began last year) we (I and two others) started a project to test a number of different things (will probably come back with a report). The project uses insulated plastic foam supers for 10-frame Medium frames (159 mm high). All frames are supposed to be plastic with plastic foundation. Two different cell sizes are used, 4.95 mm and 5.5 mm. Thus a group of colonies have only 4.95 and another group 5.5. Not all combs are completely that way in all colonies. Next year it will.
Vettenhalt Yellow plastic frames with 4.95 mm cellsize and black with 5.5 mm.

Low moisture Heather honey

This year cell sizes were somewhat mixed for different reasons, especially in supers. So when I harvested a number of supers with well capped Heather honey combs with different cell sizes in the same super I took the opportunity to measure the moisture content again in a similar way as 10 years ago.

This time, I could compare 4.95 with 5.5. And 5.3 with 5.5 (I had some plastic frames with cell size 5.3 also for a certain reason I will come back to in the report to come).
The notes I had from the test 10 years ago I have not found. But I found those I made this year. They are seen in the table.


4.95 mm 5.3 mm 5.5 mm capped honey

uncapped honey


16.0% 17.0% X
2 16.5% 17.5% X
3 16.0% 16.2% X
4 17.0% 17.3% X
5 15.9% 16.0% X


Similarities and differences

The tendency that smaller cell sizes means less moisture in the honey holds. But the differences between cell sizes are smaller this time. Another difference is that the difference between the middle frames and the outer ones in supers with the same cell size was not found now with well insulated supers.

The difference between the cell sizes are greatest when 5.3 and 4.95 are compared. The difference between 5.3 and 5.5 was not as big (not per 0.1 mm cell size either).
The moisture content was for me surprisingly low considering that it was almost pure heather honey in the combs checked. Usually Heather honey has higher moisture content, probably due to it’s gathered late in season when temperature difference between day and night is bigger. But it was unusually warm in August this year when the Heather was in bloom and remperature was not very low in nights.

When trying to understand the results I think it helps being aware that when bee colonies build their own combs without the help of foundation many have observed they build (when they are adapted after a period of perhaps several years) mostly between about 4.7 and 5.1 mm cell size in the brood nest and 5.2-5.5 (approximately) in honey area.

When the bees have collected a lot of honey for the winter period, most of the empty cells are small. When spring comes the first brood is reared in small cells. Low moisture honey is closest to brood then. Is that of any importance for the bees? Later in season some brood is reared in slightly larger cells as well. Towards the end of the season the queen lays almost only in small cells again.