hard boar glue

My teenage boar(almost 7 months) has gotten boar glue on my other guinea pig(2.5 years) twice in the past week or so. It's super gross and I don't know how to prevent it or if my teenage boar will stop doing it eventually. I additionally am wondering if there is a better way to get rid of it...

Poor Icy.. brownie has put his boar glue on icy's back. Icy's hair become tangled to a bunch with white cement like thing stuck. I tried cleaning with warm water and soap. He just started crying loudly. Poor boy. I was forced to cut of his hair in the affected area. Is there any way I can stop...