Quick Answer
Lava is a naturally occurring underground liquid and a reusable heat source in Sandustry. The official wiki says it can be frozen into Scoria with Snow, broken into Cinder, moved as a solid, and reignited to restore Lava at the destination. It can also ignite compatible material passing over Lava held in Filters, supporting automated Slag and Flower burning.
Do not attempt to handle Lava like Water. The official transport method is a conversion chain, not direct pumping: Lava becomes Scoria, Scoria yields Cinder, and ignited Cinder returns to Lava. Build that conversion in a contained work area and test it before connecting valuable production.
The Confirmed Lava Conversion Chain
The Lava page places natural Lava deep underground in the Lava Cave. Snow from the Cryoblaster can freeze it into Scoria, and destroying Scoria produces Cinder that can travel by Grabber, Conveyor Belt, or Launcher. When Cinder is ignited, it becomes Lava again, allowing heat to be relocated without moving the liquid itself.
This chain is strategically important because it converts a dangerous liquid into a logistics-friendly solid for the middle of the trip. It also gives the player a visible checkpoint: if Cinder reaches the destination, the transport stage worked even before ignition. Exact conversion speed and the best batch size are Pending confirmation because the cited official page does not define stable throughput targets.
| Stage | Material | Confirmed action | Main risk |
|---|---|---|---|
| Source | Lava | Find naturally underground | Accidental contact and uncontrolled flow |
| Freeze | Scoria | Apply Snow, such as from the Cryoblaster | Freezing beyond the intended boundary |
| Package | Cinder | Break Scoria and collect the solid output | Mixing Cinder with unrelated belt cargo |
| Transport | Cinder | Use Grabber, Belts, or Launchers | Premature ignition near flammable material |
| Restore | Lava | Ignite Cinder at the destination | Leaks from an incomplete container |
Using Lava as Automated Heat
The official Lava page says Lava held inside Filters can ignite pixels that pass over it when those pixels are burnable. Its example uses Slag and Flowers, while the Burnt Slag page confirms that running Slag over trapped Lava can automate ignition. This replaces repeated manual Flamethrower use with a fixed heat station.
Containment is the heart of the design. The wiki describes setting a Filter to allow only Cinder, placing a solid block below it, filling the Filter with Cinder, and then igniting the contents. Treat that as a concept to reproduce carefully in the current build, because placement details, tool behavior, and patch changes can alter how a compact setup behaves.
Before enabling the input belt, verify these points:
- The Lava is fully contained and cannot enter a Water line.
- The incoming material is actually burnable and has a clear exit.
- Cinder cannot fall into the heat cell by accident after the setup is active.
- A safe shutdown route exists if output backs up.
- Valuable structures are not directly below an experimental chamber.
Lava, Water, and Snow
Snow solidifies Lava into Scoria, while Water landing on Lava creates Steam according to the official Lava page. The Steam store description also uses redirected Lava as an example of environmental problem solving. These interactions make Lava useful, but they also mean nearby water networks can change the state of a heat cell unexpectedly.
Keep cooling material on a controlled side of the chamber rather than above an open Lava pool. If Water enters, expect Steam and provide vertical space instead of trapping gas inside production. If Snow reaches the Lava, the heat source may become Scoria and stop working until the conversion is reversed through Cinder.
Troubleshooting a Lava Heat Cell
If Slag does not ignite, first confirm that Lava is present where material touches the transport surface. The official page says the Filter must be completely full with Lava for the described Slag-over-belt interaction. Do not compensate by spreading open Lava through the factory, because a contained fault is easier to inspect than a new uncontrolled hazard.
If the chamber cools into Scoria, look for Snow intrusion or Cryoblaster use nearby. If Steam appears, inspect Water routing and roof clearance. If Cinder ignites too early, separate the transport belt from any Fire source and restore Lava only inside the prepared destination container.
Commissioning a New Lava Route
Run the conversion chain as separate tests before joining it to production. First freeze a small edge of the source and confirm that the resulting Scoria can be broken into Cinder; next move that Cinder over the intended Belt or Launcher route without ignition. Only after the destination container is visibly complete should you introduce Fire and confirm that Lava remains where expected.
The staged approach distinguishes four different failures: incomplete freezing, lost Cinder, premature ignition, and leaking Lava. A single end-to-end test can hide which stage failed and may scatter several material states through the factory at once. Keep Water and Snow sources closed during the ignition test so their documented reactions do not obscure the result.
After the heat cell works, add the target material gradually. Observe whether Slag reaches the hot contact point, whether Burnt Slag leaves the area, and whether accumulated output blocks later input. The official sources establish the reactions, but exact capacity and a universal compact blueprint are Pending confirmation, so a locally measured operating limit is safer than a fixed copied design.
Deciding When Lava Is Worth the Complexity
Lava automation is most useful when repeated manual ignition has become the limiting task and the factory already has controlled solid logistics. If the Slag supply is intermittent or the downstream Press is blocked, a permanent heat cell does not solve the actual bottleneck. Stabilize those stages first, then use Lava to remove manual work from a chain that already has a clear input and output.
For a temporary or low-volume line, manual Flamethrower use may remain easier to inspect and shut down. The official wiki presents both manual and Lava-based burning, so automation is an option rather than a requirement. Choose the simpler method until the additional conversion, containment, and recovery work has a clear operational benefit.
Sources
Sandustry is developed by Lantto Games and published by Hooded Horse. This independent guide is not affiliated with or endorsed by the developer, publisher, Valve, or Microsoft.