Dry looking coronary band?

I noticed lately that my horses coronary bands have been looking rather dry and flaky. I put hoof polish on his hooves 4 or so times a week but I don't know if it helps them. Someone told me that rubbing over the coronary bands with a sandpaper like sponge and then putting mineral oil on it would be good.

Anyone know what I can do to moisturize them somehow?

Corona works wonders! It's a thick ointment that works great for moisterizing

Corona Ointment - Horse.com

Thank you!