Filter - Sandustry Wiki
Learn how Sandustry Filters use Allow and Block rules to separate materials, route Shaker outputs, and diagnose sorting failures.
Overview
The Filter is a configurable logistics building that separates material flow into two paths. One path continues in the direction of its Conveyor Belt surface, while eligible material can fall through to the space below. The selected resource and the active Allow or Block rule determine which material takes which path. Official Wiki — Filter
This page describes the current documented rule and its physical limits. It does not claim a fixed throughput, best factory layout, universal Shaker ratio, or guaranteed way to recover every blocked line. It also keeps one important evidence boundary visible: the checked sources do not establish that a current Basic Filter can directly select Residue.
Quick Facts
| Field | Verified value | Source |
|---|---|---|
| Type | Building | Official Wiki — Filter |
| Basic configuration | One selected eligible Solid resource | Official Wiki — Beginner’s Guide |
| Rules | Allow or Block | Official Wiki — Filter and Beginner’s Guide |
| Output paths | Down through the Filter or onward along the Conveyor Belt direction | Official Wiki — Filter |
| Direct Basic Filter selection of Residue | UNKNOWN | Filter, Beginner’s Guide, and Residue |
Allow and Block Rules
Allow sends the one selected eligible resource downward through the Filter. Other material that does not take the falling path continues as it would on a Conveyor Belt. Block keeps the selected eligible resource on the continuing belt path while other pass-eligible material falls through. Both definitions are stated by the official Filter page and the official Beginner’s Guide.
The rule targets one selected resource identity. The official Beginner’s Guide describes a Basic Filter as selecting one Solid resource, and describes Advanced Filters as extending the same single-resource model to Solid, Liquid, and Gas resources. That distinction is a documented scope boundary, not a recommendation to use an Advanced Filter in every design. Official Wiki — Beginner’s Guide
| Mode | Selected eligible resource | Other pass-eligible material | Source |
|---|---|---|---|
| Allow | Falls through the Filter | Continues along the belt path | Filter and Beginner’s Guide |
| Block | Continues along the belt path | Falls through the Filter | Filter and Beginner’s Guide |
Allow and Block change routing; they do not create, consume, or process a material. A Filter therefore cannot replace the machine that produces an input, and it does not increase the documented output probability of a Shaker. Official Wiki — Filter and Official Wiki — Shaker
Physical Conditions That Affect Sorting
A correct rule still needs a usable physical path. The official Filter page identifies several conditions that can prevent the expected separation:
- A solid block directly below the Filter can trap pixels instead of letting them leave through the falling path. Official Wiki — Filter
- In a tall mixed pile, density and pile position can keep an otherwise eligible upper pixel from reaching the Filter surface. Official Wiki — Filter
- A pixel can change into a type that is no longer eligible while passing through. The official page gives Sand or Seed touching Water and becoming Wet Sand or Wet Seed as examples. Official Wiki — Filter
- Material that stays on the continuing path still needs room to leave; changing Allow to Block does not clear a blocked destination by itself. This troubleshooting conclusion follows from the two documented paths. Official Wiki — Filter
For diagnosis, test a small visible sample and watch both exits. First confirm the selected resource and mode, then inspect the space below, the continuing belt route, and whether the target pixels actually reach the Filter. Those checks isolate the documented rule from a separate material-flow blockage.
Filters Around a Shaker
A Shaker processes Wet Sand into Residue and may also produce Gold. The official Shaker page states that Gold exits below while Residue remains above and moves slowly toward the side. This creates separate physical routes that a factory can manage with logistics buildings. Official Wiki — Shaker
Current Early Access gameplay shows Filters being used in mixed-material routes around Shaker outputs. One recording discusses changing a sorting setup while handling Wet Sand and Residue; another shows Filter-based routing while the player works with Gold, Residue, Sand, and Wet Sand. These scenes support the practical relationship between Filters and Shaker-output routing, but the visible evidence does not conclusively show Residue selected in the Basic Filter UI. Factorio Expert plays Sandustry, 02:02–02:41 and Early Access gameplay, 42:42–50:23
The safe implementation rule is to select a resource that the current Filter UI actually offers, then choose Allow or Block according to the path that resource should take. Do not copy a layout and assume its unseen selection is Residue.
Residue Compatibility Boundary
The direct question “Can a current Basic Filter select Residue?” remains UNKNOWN in the checked evidence.
The official Beginner’s Guide describes Basic Filter selection as Solid-only. The official Residue page classifies Residue as Slushy. The official Filter page discusses moving Residue over a Filter, but moving over the structure is not the same as appearing as the selected resource in its configuration UI. Official Beginner’s Guide, Official Wiki — Residue, and Official Wiki — Filter
The gameplay recordings are consistent with Residue-related routing, but neither cited segment provides conclusive UI proof of direct Basic Filter selection. A route can separate Residue indirectly by selecting another eligible material and sending Residue along the opposite path. Factorio Expert plays Sandustry, 02:02–02:41 and Early Access gameplay, 42:42–50:23
Until a current-build capture shows the Filter type, resource selector, selected resource, and active rule together, this page does not claim that a Basic Filter can directly select Residue.
What a Filter Does Not Prove
- A working example does not prove a universally best layout, machine count, or orientation.
- A routing change does not establish a fixed throughput or production gain.
- Seeing Residue travel over a Filter does not establish direct Residue selection.
- Seeing mixed materials separate does not reveal the selected resource unless the UI is visible.
- A Filter cannot process Wet Sand or change the Shaker’s documented Gold probability. Official Wiki — Filter and Official Wiki — Shaker
Troubleshooting Checklist
- Confirm whether the active mode is Allow or Block and compare it with the documented paths. Official Wiki — Beginner’s Guide
- Confirm that the selected resource is eligible for the installed Filter type. Official Wiki — Beginner’s Guide
- Clear the space immediately below the Filter so the falling path is open. Official Wiki — Filter
- Reduce a tall mixed pile so the target material can reach the Filter surface. Official Wiki — Filter
- Check whether contact with Water changes a material while it is passing through. Official Wiki — Filter
- Inspect the continuing Conveyor Belt route and any downstream Launcher; both destinations must remain physically usable.
FAQ
What does a Filter do in Sandustry?
It routes one selected eligible resource differently from other pass-eligible material. Depending on Allow or Block, the selected resource either falls through or continues along the Conveyor Belt path. Official Wiki — Filter
What is the difference between Allow and Block?
Allow sends the selected eligible resource downward. Block keeps the selected eligible resource on the continuing path and lets other pass-eligible material fall. Official Wiki — Beginner’s Guide
Can a Basic Filter directly select Residue?
UNKNOWN. The current source set does not show Residue selected in the Basic Filter UI, and the official documentation leaves a Solid-versus-Slushy classification conflict unresolved. Official Beginner’s Guide and Official Wiki — Residue
Why is allowed material not falling through?
Check the space below, whether the selected pixels reach the Filter, and whether a material reaction changed their type. Each condition is described by the official Filter page.
Does a Filter increase Shaker output?
No production increase is established by the checked sources. A Filter routes compatible material; the Shaker remains the processing building with its own documented input and output rules. Official Wiki — Filter and Official Wiki — Shaker
Related Guides
Update History
Updated: 2026-09-04, Asia/Shanghai — Published the verified Allow/Block and physical-routing evidence while retaining direct Basic Filter selection of Residue as explicitly unknown.