Edit: Just tried this and the talc can be dropped. But whenever the inventory is full, and a stack is used up from crafting, the crafted material tries to go in inventory first before the used-up ingredients are removed, but since the inventory is full while the used-up ingredients are still present, the newly crafted stack ends up on the ground.
Heya gimmegames- you haven't appeared to have crushed any barnacles for a couple of days. Was this something more recent? Also, if your pack is full and you crush a barnacle or stack of them in your inventory, the talc stack replaces it. So, can you explain with as much detail as possible what happened?
I had about 16 barnacles and chose to crush 15 of them - I usually do that so that future barnacles will be placed where I expect to find them in my inventory. I had been crafting hatchets, and they were being dropped onto the ground as I was making them, due to my inventory being full - which was fine with me. The previous hatchet made used the last of the barnacle talc, so I was crushing more so that I could continue.