Sandustry Slag and Residue Processing
What players call slag the game calls Residue. Here is the burn rate, the auto-burner setup, and the drop height the Kinetic Press actually needs.
GamePrimer EditorialUpdated Verified
Burn Residue to get Burnt Residue — only one pixel in four survives the fire, the rest are consumed. Then drop the Burnt Residue onto a Kinetic Press from at least 25 blocks up, or it just piles on top and jams the press.
Slag, Residue, and why you see both
Search results and player chat call this stuff slag, and the burnt version burnt slag.
The game and the official wiki call it Residue and Burnt Residue, and the press that
processes it is the Kinetic Press — though the game’s own art file for that building is
still named Kinetic_Slag_Press.
Same material, same building. The pages here use the in-game names so they match what you see on your screen.
Where Residue comes from
Drop Wet Sand onto a Shaker. Every single Wet Sand pixel produces one Residue — that part has no dice roll. One in four additionally produces a Gold.
So Residue is not a side product you can opt out of. If you run a Shaker, you are producing Residue at exactly the rate you are producing Wet Sand, and it will bury the machine unless you move it somewhere.
The burn, and its real rate
Residue has to meet Fire. When it does, each pixel has a 25% chance to become Burnt Residue and a 75% chance to simply be consumed with no output.
That number is the single most important figure on this page. Three quarters of your Residue is going to vanish, by design, and no setup changes that. Plan the throughput of everything downstream around a quarter of what goes in.
Fire also spreads from burning Residue to any Residue touching it, which is what makes a big pile self-sustaining: with enough input, a heap you ignite once keeps burning and keeps producing without being relit.
Ways to light it
- Flamethrower — manual, fine for your first attempt
- Rocket Launcher with the napalm upgrade — manual, at range
- Pyro Dispenser (tier 3, 2,000 Gold) — fires a flame burst every 3 seconds, fuelled by an adjacent Thermal Buffer
- Lava trapped in a Filter — needs the Filter and the Flamethrower (650 Gold together), then runs with no fuel and no moving parts
The Lava auto-burner
This is the setup worth building, and it costs nothing to run.
- Set a Filter to allow Cinder only.
- Put a solid Block directly underneath it. Now pixels can enter the Filter but have no way out, so they stay there.
- Fill it with Cinders and ignite them. They melt back into Lava and the Lava is stuck in place.
- Run Residue along the Conveyor Belt over the top. Residue touching the belt above full Lava ignites and turns into Burnt Residue.
Cinders come from Lava the long way round: freeze Lava with Snow to make Scoria, break the Scoria with any weapon to get Cinders, carry the Cinders wherever you want. Note that Cinder needs the Flamethrower’s direct flame to melt back — passive heat will not do it.
The Kinetic Press, and the 25-block rule
The Kinetic Press (tier 2, 500 Gold) turns 1 Burnt Residue into 1 Gold and 1 Seed. Unlike the burn, this step never fails.
What it needs is height. The Burnt Residue must fall onto the press from 25 blocks or more. Below that, it does not transform — it lands on top of the press and sits there, blocking anything else from reaching it. Everything that is not Burnt Residue does the same thing.
The outputs fall through and come out of the bottom, so leave that side clear.
Clearing blockages
The Kinetic Press has no Conveyor Belt built into it, which the Shaker does. Nothing sweeps its surface for you.
The fix is a row of angled Launchers along the top of the presses, aimed at a gap in the wall. They fling anything resting on the surface off to the side, without disturbing pixels that are still falling.
What the chain is worth end to end
Starting from 2 Sand:
| Step | What you have |
|---|---|
| 2 Sand + Water | 4 Wet Sand |
| 4 Wet Sand → Shaker | 4 Residue, and 1 Gold |
| 4 Residue → Fire (25%) | 1 Burnt Residue |
| 1 Burnt Residue → Kinetic Press | 1 Gold, 1 Seed |
| 1 Seed → Water → Planter Box → harvest | 1 Gold, 4 Amethelis |
Three Gold from two Sand. Stop after the Shaker and it is 1 Gold from 2 Sand — the burning and pressing chain is where two thirds of the value is, which is why it is worth automating the fire.
Related
- How to Get Gold in Sandustry — every source, and the Collector rule
- Sandustry Filters Explained — the Filter behaviour the auto-burner relies on
- Sandustry Production Chains — the same chain, step by step
