Bone Ash (Ca5(PO4)3OH ) is a secondary flux which generally acts as an opacifier in glazes. Can cause crawling and blistering.
Craftreat Teflon Bone Folders for Card Making - Large Bone Folder - Teflon Bone
2PCS Leather Working Tool Bone Folder For Leather Craft Scoring Folding Creasing
3 PCS Curved and Straight Bone Folders, Paper Creaser Set, Bone Folder Tool, Scoring Tool, for Folding Papers Crafting Scrapbooking, Leathercrafts Bookbinding(White)