Spartan & Tinkers' Metals

Electrum Smelting

Again, exactly like this (3 gold, 3 silver), but can use charcoal instead of coal; takes 4 seconds

Steel Smelting

This exact configuration is required (5 iron); takes 5 seconds Note: In v1.3 and later, this is no longer the recipe. It now requires a coal in the 6th slot, and can use either coal or charcoal in the bottom slot

Invar Smelting

No changes (4 iron, 2 nickel) except coal or charcoal; takes 4 seconds

Bronze Smelting

As before, no variations (5 copper, 1 tin) other than charcoal; takes 4 seconds