Sorting building

Sandustry Filter: How Filters Work, Gold Sorting and Jam Fixes

Quick answer: a Filter is a Conveyor Belt that can be configured either to let one chosen pixel fall straight down, or to let everything fall except one chosen pixel. Pixels outside the rule keep moving forward like a normal Belt. Liquids and gases pass through, so Filters sort solids best when the drop space is clear and Water is not crossing the line.

Allow one or exclude one Blocks the player Drop-through sorting Gold splits well

Fix Conveyor Problems How Belts Carry Pixels

At a glance

Filter quick facts

Configurable to pass one pixel type, or everything except one
Acts like a normal Conveyor Belt for every other pixel
Lets liquids and gases pass through, but blocks the player
Allowed pixels fall straight down through it

Sandustry Filter diagram comparing a water-crossed blocked filter with a clean Gold drop-through sorting setup — Filter checkpoint: keep the target pixel, the drop space, and any crossing Water separate.

How Filters Work, Step by Step

Sorting is only half configuration. The other half is density, because a Filter drops pixels downward and a crowded pile does not always cooperate.

Step 1

Set allow or exclude

Configure the Filter to drop only a chosen pixel, or to drop everything but a chosen pixel. For any pixel outside that rule, the Filter carries it onward exactly like the Belt it replaced.

Checkpoint: the rule you set matches the pixel you want separated.

Step 2

Filter the densest pixels first

Heavy pixels settle at the bottom of a pile, so they are the ones a Filter can pull cleanly. To split Gold out of Sand, allow Gold through — once the pile has settled, Gold is the layer that should sit nearest the Belt.

Checkpoint: the densest pixel lines up nearest the Belt and drops through.

Step 3

Keep liquids out of the pass

A Filter does not block liquids, so Water can flow through while solids are dropping. If it touches Sand or Seeds mid-fall it wets them, changes their type, and jams the machine.

Checkpoint: no Water crosses the Filter while pixels fall.

Step 4

Try the Cinder auto-burner

Put a solid block right below a Filter and pixels enter with no way out. Trap Cinders this way, ignite them into contained Lava, then run Residue over the top for a compact auto-burner.

Checkpoint: Cinders stay trapped under the Filter and ignite on demand.

Filter Not Working: Symptom, Cause, Fix

A Filter usually fails because the rule is wrong, the pile order fights density, or the falling pixel changes type on the way through.

Symptom	Likely cause	Fix
Target material rides past the Filter	The mode is set backward: allow one vs exclude one.	Recheck the rule before rebuilding the belt line.
Nothing drops from a mixed pile	The target pixel is lighter than the layer beneath it.	Filter the densest material first, especially for Gold sorting.
One pixel is stuck inside the Filter	An allowed pixel changed into a disallowed one while falling through.	Remove the stuck pixel by hand and keep Water away from Sand or Seeds at the drop point.
The drop-through exit clogs immediately	There is no clear space below the Filter.	Open the exit below or use the blockage deliberately only for a Cinder trap.
Water keeps crossing the sort point	Filters do not block liquids, so Water is part of the route whether you wanted it or not.	Route Water around the Filter or move the sort point away from the wet line.

Best Early Uses

Use Filters where one stream needs to split cleanly; avoid using them as generic Belt decoration.

Gold sorting

Let Gold drop into collection

When a stream contains Gold and lighter material, set the Filter for the pixel you want to remove and give the drop point empty space.

Review Gold flow

Byproduct control

Keep Residue away from the main line

Sorting matters most when a byproduct can bury the useful output or redirect flow into a dead end.

Fix Residue backup

Debugging

Check the rule before rebuilding belts

If a material rides past the Filter, confirm whether the current mode means allow one type or exclude one type.

Open conveyor diagnostics

Core sorting rule

Filters can be configured either to pass one pixel type or exclude one pixel type.
They do not block liquids or gases, so crossing Water can interfere with solid sorting.
They are most reliable when the target material can actually fall through a clear drop lane.

Where you still need to test your own line

Use these layouts as sorting rules first; the fastest final shape still depends on how many pixel types share the lane.
Edge cases still come from density, drop distance, and whether the chosen material has room to fall cleanly.
Early Access updates can change specific interactions, so re-check unusual sorter behavior after patches.

Primary Sources

Next step

If the wrong material is reaching a machine, diagnose the route with Conveyor Problems. For early Gold lines, compare the flow against the Gold Factory Blueprint.

Source note: This recommendation is source-based, not an independently benchmarked build.

Official source