Well Tim, this is a new one to me. Is it on both ceiling and walls? You might try taking a 6" putty knife and see if it will scrape off. Maybe it didn't stick to the smooth plaster that well. Either way you have a long process ahead of you. If I can ask, is it really bothering you that much? I own my own Painting and Home Repair business and every job is different I'm constantly thinking how to make my job faster and easier. On this situation I would even take a belt sander to it if nothing else worked.I'll try anything. If you find an easy way to do this, please let me know, I'm sure someone will want me to do it someday. Keep us posted. Ron J.