Horn also has a temperature at which it loses it's memory. I have never worked the water buffalo horn which is what most of the black buttplates are made from. However, cattle horn loses it's memory at a little over 300 degrees. You can't get there with boiling water as it only gets to 212 degrees. I heat horn in lard and monitor the temp with a candy thermometer. Once it is heated to about 300 all the way through you can move it around quite readily. Cold it can be filed, rasped, sanded and cut with chisels (but not near as fast as wood). I shape the exterior with rasps, and a wood finish scraper. At slightly higher temperatures horn will weld like hot plastic. I have watched it done but haven't done it myself.
