On the 315 I make my own to fit. I use Black Cotton Twill (AKA: jeans material ) The fit should be snug at the wrist and just tight enough at the elbow to not fall down. Simple piece of elastic sew in on each end. The secret is that they have to hold up to de-greasing and washing. They DO SAVE the sleeves from not just coal, but the grease from "Oiling Around"
On a coal burner like 315, where the back head is out the back of the cab, a kerchief also saves your neck / collar from becoming a repository of hot cinders.