Does anyone have a better solution for lines on eggs from rollaway boxes?

Hello everyone!

I just have a quick question. I have roll away nest boxes from Best Nest Box and I cannot find a good solution to get rid of these lines. Over the summer I would spray them out with the hose but that’s not an option at the moment. It weirdly only happens in my one coop but not the other. I’m thinking of bringing a bucket and scrub brush in here and adding that to the chore list.

Any suggestions would be greatly appreciated.

Thanks