Hi Fred
Less harmful? To what - the burl, your hands, your blood pressure? ;) Picking, scraping, occasional profane utterances all are time honored and often the only way to get this stuff free of bark. I've even tried using a fine steel rotary brush in a Dremel to get rid of some stuff, but hand work is often the only way.
<img src="http://www.enter.net/~ultradad/blacklocustburl02.jpg">
I spent hours picking bark bits out of the hundreds of tiny points on this locust burl. You want to talk about serious hand cramping? I was using a dental pick given to me by a dentist friend of mine, and all I can say is, I am glad I am not a dentist! A larger handle would have made a huge difference.
Some people hose these things down with a pressure washer, but unless it is huge or anchored down somehow, it is going to be shot across the field like a soccer ball.
Good luck with it. It is usually worth the effort.
Bill