Welcome to B&B.
I got the Teak in medium and there is plenty of room in there for any size brush; my largest knot is 27mm. I use it daily all year round.Large satin black scuttle ordered. Really come into its own when the cold weather hits
Don't use boiling water as it will kill the lather. Fill with hot tap water first to warm it up, then replace water in base after > 3 minutes for that warm lather through the shave.Do you add boiling water to yours or just hot water from the tap and do you let that sit for a few minutes before starting a lather?