Smelting
Smelting converts one item into another using a Furnace and fuel. Unlike Crafting, smelting takes time and consumes fuel as it runs.
Using a furnace
A furnace has three slots: the item to smelt on top, the fuel below it, and the result on the right. While it has both an input and burning fuel, the furnace works through its input one item at a time and lights up.
One smelt takes 200 ticks — 10 seconds
A furnace only draws a new piece of fuel when there is something it can smelt, so an idle furnace never burns anything. Once a piece is alight, though, it burns to the end regardless: taking the input out part-way through wastes whatever is left of it.
Progress is not banked. If the fuel runs out mid-item, or the input is removed, or the output slot fills up, the progress bar drops to empty and that item starts again from the beginning.
Fuel
| Fuel | Burns for | Items smelted |
|---|---|---|
 Lava bucket |
20000 ticks (16m 40s) | 100 |
 Coal or charcoal |
1600 ticks (1m 20s) | 8 |
| Any block made of wood | 300 ticks (15s) | 1.5 |
 Stick or  Sapling |
100 ticks (5s) | 0.5 |
Nothing else burns. An item that is not on this list leaves the furnace unlit.
A lava bucket is consumed whole, bucket and all — the furnace decrements the fuel stack and returns nothing, so burning one costs the container as well as the lava.
Charcoal is the same item as coal and burns for exactly as long.
The blocks that count as wood are Wooden Planks, Wood logs, Wooden Stairs, Fence, Trapdoor, Crafting Table, Chest, Bookshelf, Jukebox, Note Block, the locked chest and the wooden Pressure Plate. Each burns for the same 300 ticks no matter what it cost to make, so what a piece of wood is worth as fuel depends entirely on how it is cut. One Wood log crafts into four Wooden Planks, which quadruples its fuel value from 300 ticks to 1200. Going any further loses: four planks make one Crafting Table, turning 1200 ticks of fuel into 300.
Sticks are worse still. Two planks yield four sticks, trading 600 ticks for 400, and the six sticks a Fence costs would have burned for exactly as long as the two fences they make.
Wooden doors and signs don't burn. The furnace tests the item's id against the block list, and both have a non-block item id when in an inventory
Smelting recipes
| Result | Qty | Recipe |
|---|---|---|
 Brick | 1 |  |
 Cactus Green | 1 |  |
| Charcoal | 1 |  |
 Cooked Fish | 1 |  |
 Cooked Porkchop | 1 |  |
 Diamond | 1 |  |
 Glass | 1 |  |
 Gold Ingot | 1 |  |
 Iron Ingot | 1 |  |
 Stone | 1 |  |