Sandustry Filter Guide: Allow, Block and Prevent Jams

Understand the machine's job before placing it

The Filter provides explicit material selection where gravity alone is too ambiguous. It can be configured around one solid material and used in either an allow or block plan. The rest of the layout must still give accepted and rejected pixels somewhere to move; configuration does not create output space.

Liquids and gases can pass through the structure according to the official page. That makes the Filter unsuitable as the only barrier beside Water, Steam, or another fluid. Design containment independently, then use the selection behavior for the solid stream it is meant to control.

Follow the documented input and output rules

Choose the target material and verify whether the current state allows that material or blocks it. Use the on-screen editing interface in the installed build because Update #1 improved Filter editing and key prompts can change. Send one known sample from each relevant material before trusting a mixed production feed.

Density continues to affect how pixels approach and leave the Filter. A heavier or more mobile material may settle against a different face than the diagram suggests. Contact reactions can also create a new material inside a cell, especially when a solid arrives wet. The Filter then appears incorrectly configured even though its passage is physically occupied.

Build a serviceable layout

Build a staging pocket before the Filter and two visible collection paths after it. The staging area evens out bursts and gives you a place to stop input. Keep the selected stream away from the rejected stream after separation; allowing the routes to rejoin makes a successful filter look ineffective.

Leave direct access to the building and the cells immediately around it. You should be able to clear a jam, change the target, and sample both outputs without opening the surrounding factory. Use a dedicated fluid drain when Water or another liquid accompanies the solids.

Measure sustainable throughput

Treat Filter as one boundary in a longer chain. Start with empty or recorded buffers, count how much a mixed solid stream reaches the input during a fixed interval, and compare that with the selected allowed or blocked solid route leaving the output. Record material still inside the chamber. A growing reserve before the machine identifies an intake or processing limit; a growing reserve after it identifies a collection or destination limit.

Do not infer an exact rate from a short animation. Let startup material clear, repeat the interval, and test again after saving and loading. If supply arrives in bursts, record both average flow and the largest burst. Add parallel capacity only after the same boundary limits two clean observations. Otherwise extra machines can hide a routing fault while consuming space, power, heat, cold, or scarce construction resources.

Diagnose the first failed boundary

When the wrong solid passes, pause the feed and inspect the selected material and allow or block state. Clear every cell around the Filter before retesting; an old sample trapped inside can make the first result misleading. Confirm that the source did not transform before reaching the building.

When all solids stop, inspect output clearance and material inside the structure. Remove liquid or a reacted solid from the test cell, then try one dry known sample. If liquids are the concern, remember that normal pass-through is documented behavior and add a proper fluid route rather than repeatedly changing the solid rule.

Apply the v0.5.6 version notes

Update #1 introduced better Filter editing. This page avoids hard-coding one physical key because bindings and prompts can differ, but the allow-or-block material model is documented on the current official wiki. Check the live interface after any control update.

Update #3 raises Lava density and changes several material interactions. Never use a Filter as trusted Lava containment, and retest any shared separator whose order depended on the older density. A destructive material belongs in a limited test cell before it reaches a general sorting bank.

Validate the design in a small test cell

Build one isolated Filter with a limited input sample, visible output pocket, and a way to stop supply. Label the game version and active mods. Observe the expected transformation, any byproduct, where each pixel settles, and what happens when the destination fills. Then clear the cell and reverse the loading order if two materials share space. A repeatable small test gives a stronger design basis than a screenshot of a large factory.

After the test passes, copy the geometry into production while keeping access to the input, output, and removal controls. Leave enough room to inspect or drain the machine without opening a neighboring line. Recheck the route after patches that mention the machine, its materials, density, heat, fluids, energy, or building events. Keep the prior measurement with its version so a future change is visible instead of becoming an unexplained slowdown.

Use the pre-launch checklist

Before opening full supply, confirm that the input really is a mixed solid stream, the planned result is the selected allowed or blocked solid route, every required power or temperature connection is active, and no incompatible material can enter. Verify output clearance, overflow capacity, a shutoff point, and a safe path for the player. Take one recovery save before connecting a rare or destructive input.

During the first long run, compare starting and ending inventory at every boundary. Watch for material trapped inside building cells, a mixed network, a full destination, and a reserve that only delays failure. If the line remains balanced through its normal burst and restart conditions, record the observed rate and promote the module as the factory's current versioned standard.

Field facts

Troubleshooting

• Every solid stops.

  Clear the Filter cells and both outputs, verify the mode, and retry with one dry labeled sample.

• Water crosses the Filter.

  That is expected; liquids and gases pass. Add dedicated fluid containment or transport.

• The selected material reaches the wrong side.

  Confirm allow versus block, then inspect whether density, geometry, or a contact reaction changed the material before the boundary.