Wiki says it should be dropped by Black Hand Pirates.
I’ve never seen it dropped by those on the Black Galleon and in the desert.
I think it should be dropped by JUNGLE pirates tho, but it doesn’t.
It’s only found in chests at the Floatsam.
Now, thisstuff is not craftable (and I think this should be fixed as there should be a recipe for it) but it should at least be dropped by NPCs.
Limiting it to crates makes it too difficult to find.