- Burnt Slag: Created by baking Slag over a bed of lava.
- Lava Bath: Requires a completely packed container of Cinder torched into lava.
- Gold Source: Process Burnt Slag through Kinetic Presses to extract Gold.
- Density Physics: Wet Spores have neutral buoyancy and require agitation to move.
- Automation: Use Launchers and Filters to separate products efficiently.
Understanding Burnt Slag
Burnt Slag is a critical mid-game resource in Sandustry, serving as the primary gateway to wealth through Gold production. Unlike standard Slag, this material undergoes a thermal transformation process that allows players to extract precious metals. The conversion relies entirely on thermal mechanics within the game's physics engine.
Video Highlights:
- Constructing a lava bath using Cinder blocks.
- Automating the baking process for Slag.
- Setting up Kinetic Presses for Gold extraction.
- Managing Spore density and water flow.
To produce Burnt Slag, you must expose standard Slag to Lava. This is not merely placing them adjacent to each other; the Slag must physically move over a heat source. The most efficient method involves creating a "lava bath"—a trench or container filled with Lava over which Slag travels on conveyor belts.
The lava container must be completely packed with Cinder blocks before torching. Any gaps or air pockets will prevent the Lava from rising to the necessary level, resulting in unprocessed Slag.
The resulting Burnt Slag retains the physical properties of the original material but changes its interaction with processing machines. It becomes the input material for Kinetic Presses, which crush it down to Gold Coins and Spores.
| Material | Source | Method | Primary Output |
|---|---|---|---|
| Slag | Mining | Digging | N/A |
| Burnt Slag | Slag | Lava Bath | Gold, Spores |
| Cinder | Mining | Deep Layers | Lava Source |
| Gold | Burnt Slag | Kinetic Press | Currency |
Constructing the Lava Bath
Building an efficient lava bath requires careful planning of conveyor belts and structural integrity. The goal is to maximize the surface area of Slag contact with Lava while ensuring the system does not clog.
Build the Container
Construct a trench at least 2-3 blocks wide and line the bottom with Cinder blocks. Ensure the sides are solid walls to prevent Lava from flowing out. The length of the trench determines how long the Slag bakes.
Install Conveyor Belts
Place conveyor belts along the bottom of the trench before filling it. These belts will move the Slag through the Lava. You may also place belts on the layer above the Lava to transport items across the top.
Pack with Cinder
Fill the trench entirely with Cinder blocks. Every empty space must be filled. If you leave a gap, the Lava level will be too low to bake the Slag passing overhead.
Ignite the Lava
Use a Flamethrower on the Cinder blocks. They will melt into Lava. Ensure the Lava level rises to the top of the trench. Look for a uniform glowing texture indicating full coverage.
Feed the System
Dump standard Slag into one end of the conveyor. As it travels over the Lava, it will transform into Burnt Slag. Use a filter at the end to separate Burnt Slag from any raw Slag that missed the bake.
If your system is slow, add more parallel conveyor lines. Increasing the width of the lava bath allows you to process more Slag simultaneously without increasing the footprint of your factory.
| Component | Quantity (Est.) | Function |
|---|---|---|
| Cinder Blocks | 20-50 | Lava source material |
| Conveyor Belts | 10-20 | Transport mechanism |
| Filters | 2-4 | Separation of Burnt Slag |
| Walls | 15-30 | Containment structure |
Gold Extraction & Spore Management
Once you have a steady supply of Burnt Slag, the next step is extraction. Burnt Slag is fed into Kinetic Presses. These machines crush the slag, yielding two primary byproducts: Gold Coins and Spores.
Gold is the currency of Sandustry, essential for purchasing upgrades like the Triple Burst drill, faster movement speed, and material scanners. Spores, on the other hand, are a biological resource used for farming Amethyst Petals.
Processing Burnt Slag provides a 1:1 ratio for Gold relative to the input volume in many setups, though Spores are also generated simultaneously. Efficient separation is key to managing storage.
Separation Strategy: Because Gold and Spores have different physical properties (and potentially different densities or interactions with specific filters), you can use a sorting system.
- Kinetic Presses: Line them up in a chamber.
- Launcher Tops: Use these to toss the crushed items into the air.
- Gravity Separation: Heavier items (or those with specific physics) may land in different bins.
- Filters: Use "Allow Only Gold" filters to catch currency while letting Spores pass through to a dedicated washing area.
| Machine | Input | Output | Usage |
|---|---|---|---|
| Kinetic Press | Burnt Slag | Gold, Spores | Currency generation |
| Launcher Top | Mixed Items | Thrown items | Separation aid |
| Filter (Gold) | Mixed stream | Gold only | Purification |
| Planter Box | Wet Spores | Amethyst Petals | High-tier material |
Advanced: The Spore Washing System
Spores generated from Gold extraction are initially dry. To convert them into a usable state for farming (Wet Spores), they must be washed. However, Wet Spores possess a unique physical property: they have the same density as water.
This means they will neither float to the surface nor sink to the bottom. They will simply hover wherever they are in the water column, making standard conveyor belt collection ineffective.
Because Wet Spores hover in mid-water, they ignore conveyor belts placed at the bottom of a pool. You must use agitation to move them.
The Agitation Solution: To wash Spores effectively:
- Create a shallow water channel (1 block deep is sufficient).
- Line the bottom with Launcher Tops.
- As dry Spores enter the water, the Launcher Tops will toss them upward.
- While airborne, they pass through the water surface, becoming Wet Spores.
- The "hopping" action pushes them horizontally toward the exit.
- Use a "Wet Spore" filter at the end to catch successful conversions and recycle dry ones.
Dry Spores
- State: Flammable, solid.
- Behavior: Bouncy, affected by gravity.
- Handling: Can be transported on standard belts.
Wet Spores
- State: Saturated, neutral buoyancy.
- Behavior: Suspends in water, ignores belts.
- Handling: Requires Launcher agitation or Planter Boxes.
Factory Checklist
Building a fully automated Burnt Slag factory is a significant milestone. Use this checklist to ensure your setup is optimized for the 2026 meta.
Factory Optimization Goals:
- Construct a lava bath with zero air pockets in the Cinder lining
- Install return loops for unburnt Slag to maximize efficiency
- Separate Kinetic Presses with walls to prevent total system backups
- Setup a Spore washing chamber with Launcher Tops for agitation
- Connect Gold storage to the main upgrade shop purchase point
Once you are farming Gold efficiently, prioritize purchasing the Material Scanner and Triple Burst drill upgrades. These will allow you to locate deep resources (like Fluxite) faster, fueling the next tier of industrial expansion.
FAQ
Q: Why is my Slag not turning into Burnt Slag?
Check your lava bath. The Cinder blocks must be packed tightly with no gaps, and the resulting Lava must be high enough to touch the Slag passing above it. If the Lava level is low, the heat won't transfer.
Q: How do I separate Gold from Spores effectively?
Use 'Allow Only Gold' filters after the Kinetic Presses. For the Spores that pass through, direct them into a water washing system. Using Launcher Tops to bounce them through the water helps separate them from any remaining dry debris.
Q: Can I use water to move Wet Spores?
No. Wet Spores have the same density as water and will not flow with currents or sink to belts. You must use physical agitation (Launcher Tops) or manual collection to move them through a water-filled chamber.
Q: What is the best use for Gold in Sandustry?
Gold should be invested into drill upgrades (like Triple Burst) and movement speed. Increasing your mining speed is the most effective way to scale your production, allowing you to gather the Cinder and Slag needed for faster processing.