Brace comb forms when feeder frames sit slightly lower than wooden frames, disrupting bee space. Castellated spacers raised 2 mm fix this by keeping frame tops flush and maintaining consistent gaps. Use the same spacers when adding supers to prevent the problem entirely.
So I've worked out that the reason you get all this brace comb on top of frames and feeders frames is because there's this little lip here. So the frames are clearly slightly thinner than wooden frames and it messes with your bee space. So I've started using these castellated spacers and putting them slightly raised. You've got about a 2mm gap just there, and that means that your— the frame lugs and the tops of the frames are totally flush with the top of the box. And then when you're putting them in your supers, all you have to do is just spin them the other way around, obviously again with the same, the same slight raised bit, so about 2mm. And that means that you can obviously have 9 and 10 frames in your supers and still get it nice and flush on the top.
