Actually, that is an interesting question…
I’m harvesting in a Sydney summer, so its pretty warm, usually in the 30s or high 20s at least and the honey is pretty runny.
Let’s say I was to open the complete length of the frame all at once, I would estimate that maybe 80 percent of the honey is out within the first 10min, however for the last 20 percent to drain out, it probably takes another 20-30 mins. So I just leave it and come back.
However, I’ve noticed that if I do open the entire length of the frame at once I get problem with the initial pressure being so great that the honey actually bursts out of the lower capped rows of the frames and runs internally down into the brood box and out the bottom of the hive onto the corflute.
So, to get around this, I only open the about a fifth of the frame length first, let the bulk of the honey run out a little, wait about 5 mins, open another fifth of the frame, wait another five mins and so forth until the total length of the frame is open. Then I just leave it for another 20-30min to completely drain.
Doing it this way takes longer (60+ mins per frame) but spills less honey.
I’m not sure if other people find this happens or my bees just don’t make strong caps? Its definitely capped - I’ve checked.