Turned a pen out of mammoth tusk ivory this week--my first using ivory. Turned out beautifully! Took it to work today to show co-workers and received lots of compliments. Unfortunately, by 4 p.m., it had cracked from one end to the other. Any tips on how to prevent such cracks in mammoth ivory? I have three more mammoth ivory blanks to turn, and don't want this to happen again! Your insights will be much appreciated!