Magnificent Chu Jian Customization Project

After disassembling the hilt (which was not a fun or easy process) I wasn't surprised to find an excessive amount of epoxy, but there was also a white plaster-like substance present I am unfamiliar with. It had been applied to the pommel where it fits into the handle, and to a lesser degree the guard where the outer edge of the blade's shoulders would otherwise contact the copper alloy. It was quite difficult to remove (requiring various abrasive bits and a rotary tool), and significantly harder and more durable than the plaster it resembled. Neither the Striking Eagle jian, nor the Heavenly Horse dao I purchased almost a year prior to the Magnificent Chu jian used this substance in their construction.

If anyone knows what this plaster-like adhesive is, please let me know. It was only after it had been removed that it occurred to me that the resulting particulates might be toxic. I would assume not, and I'm mostly curious about what it might be, because it seems like something I may want to use on a future project.