Fix ASA stringing by checking the nozzle, spool condition, temperature, travel path, and retraction in that order. Fine hairs between otherwise clean features usually point toward heat or exposed travel. Thick, irregular webs paired with rough extrusion or popping move filament condition higher in the queue. Strings that end in dots or thin restart sections point toward pressure and retraction instead of moisture alone.
This guide owns one exact failure: ASA leaving hairs or webs across open travel moves. If corners or long edges lift from the plate, use the ASA warping guide. If the defect is a dot at starts and stops, use the blobs and zits guide. Brown residue or dark smears belong in the burn-mark diagnostic.
The seven-check order
- Classify the mark. Confirm that plastic spans a non-print travel move rather than forming at one seam, dragging from a dirty nozzle, or breaking away from a support.
- Return to a supported ASA profile. Start from the printer or filament maker's profile so an inherited PLA, PETG, or mystery retraction value does not become the baseline.
- Inspect the nozzle cold and safely. Remove stuck residue and rule out material collecting above the nozzle before changing the slicer.
- Restore a trustworthy spool baseline. If the roll sat exposed or extrusion also looks rough, follow that filament maker's drying and storage guidance, then retest.
- Test nozzle temperature. Within the maker's supported range, compare one small temperature step while holding the same geometry and all other settings fixed.
- Reduce exposed travel. Inspect the preview, then test orientation or the slicer's documented perimeter-avoidance controls without hiding a flow problem.
- Tune retraction and wipe last. Make one small machine-specific change and reject it if restart gaps, thin walls, grinding, or heat-creep symptoms appear.
Match the ASA string pattern to the first useful check
| What you see | More likely branch | First controlled check |
|---|---|---|
| Fine, uniform hairs between clean towers or slots | Nozzle heat or open travel exposure | Run the same test one supported temperature step lower, then compare restart quality too. |
| Thick, irregular webs with popping, rough walls, or a spool that worsened after exposure | Filament condition or unstable melt delivery | Compare the suspect roll with correctly conditioned material before retuning the profile. |
| Strings concentrate on one travel-heavy model but not on a solid block | Part layout and repeated open crossings | Inspect travel preview, rotate the part, or test a documented perimeter-avoidance option. |
| Hairs end in dots, or the next line starts thin | Retraction, wipe, restart pressure, or seam behavior | Turn on seam and travel views; judge landing quality, not string count alone. |
| The print gets dirtier over time and dark residue rides on the nozzle | Nozzle contamination or a hotend leak | Stop safely, let the machine cool, and inspect the nozzle and heater-block area before another tuning print. |
| One vertical ridge with no plastic spanning open air | Seam placement or restart artifact, not stringing | Use the seam preview and the material-specific seam guide instead of a stringing tower. |
Check 1: confirm that the defect is actually stringing
True stringing crosses space where the nozzle traveled without printing. Follow one strand from one feature to another and compare it with the slicer's travel preview. A vertical row of bumps is a seam problem. Brown smears or material accumulating around the heater block require a contamination or leak check. Support residue stays near a support interface rather than tracing repeated travel moves.
This classification matters because the same aggressive retraction change that removes a few hairs can worsen a seam, delay the next extrusion, or hide a dirty-nozzle problem until a longer print fails.
Check 2: return to a supported ASA baseline
Use the current ASA profile supplied for the printer, nozzle, and filament family when one exists. Do not copy a retraction distance from a different drive system or treat a generic PLA tower as an ASA prescription. Direct-drive and Bowden paths store and release pressure differently, and an all-metal hotend can have different safe limits from a lined hotend.
Keep the enclosure and ventilation arrangement required for safe, stable ASA printing. ASA's need for a warm, draft-controlled environment is mainly a warping issue; opening the enclosure or blowing room air at the part is a poor stringing test because it changes layer bonding and shrinkage at the same time. Follow the printer and material maker's safety guidance for fumes and ventilation.
Check 3: inspect residue before changing settings
Prusa's current stringing guidance specifically calls out material left on the nozzle as a cause of strands sticking back to the print. With the machine stopped and cooled according to its maintenance instructions, inspect the nozzle exterior, heater block, sock, and the area above the nozzle. If material is appearing from a joint rather than the tip, solve the hardware problem before tuning.
A clean nozzle also makes the next test trustworthy. Otherwise old residue can drag through several layers and make a good profile look progressively worse.
Check 4: establish a trustworthy ASA spool baseline
ASA is partially hygroscopic, and Prusa's material guide identifies moisture absorption as a limitation. Moisture is not the automatic explanation for every hair, but it moves up the list when the roll changed after exposure, extrusion sounds rough, surfaces become uneven, or string thickness varies from one pass to the next.
Use the filament maker's own drying temperature and duration; ASA formulations and spool materials are not interchangeable. After conditioning, keep the roll sealed with active desiccant or use a controlled dry-storage path. A room hygrometer describes the room, not the water content inside the filament, so the useful proof is the same spool and same G-code before and after correct conditioning. The broader ASA moisture guide owns that narrower diagnosis.
Check 5: test nozzle temperature without sacrificing layer bonding
Prusa's current stringing guidance lists high nozzle temperature as a cause and suggests a small 5-10 C decrease as a test. Treat that as a diagnostic step inside the supported range, not a universal ASA temperature. Different brands, colors, speeds, nozzles, and hotends need different heat.
Print the same small model at the current value and one modest supported step lower. A useful result has fewer hairs and clean restart lines, consistent walls, acceptable overhangs, and adequate layer bonding. If strings improve while walls turn dull, weak, or under-extruded, the lower temperature is not a complete fix.
Check 6: inspect travel instead of guessing
Turn on travel visualization. Count the exposed crossings between islands and look for repeated moves over visible surfaces. Prusa documents perimeter-avoidance and travel-related retraction controls as ways to reduce exposed crossings. The exact names and tradeoffs vary by slicer, so use the documentation for the slicer version you are running.
First try orientation or part placement when it shortens obvious open moves without changing the functional orientation. Then test one travel control. Avoid changing travel speed, perimeter avoidance, retraction, wipe, and temperature in one slice: a cleaner result would not tell you which change worked.
Check 7: tune retraction and wipe last
Retraction reduces pressure before travel, while wipe behavior changes how the nozzle leaves the printed path. Both can help once the nozzle, spool, heat, and travel baseline are stable. Change only one machine-specific value in a small increment and stay within the printer or slicer maker's documented limits.
Judge the landing after every travel move. Too much retraction or an unsuitable speed can create missing material after travel, visible seams, extruder skips, grinding, or a hotend blockage. Return to the last clean-restart value if any of those appear. The goal is not the lowest possible string count at the expense of part integrity.
Run one repeatable ASA stringing test
- Use a small two-post or slotted test that reproduces the real hairs without creating a long warping-prone job.
- Record printer, nozzle, filament brand and color, spool exposure, drying status, profile, and enclosure state.
- Slice the baseline, save the project, and capture the travel preview.
- Print the baseline and photograph both the strings and the first extrusion after each landing.
- Change only the strongest evidence-backed branch from the table above.
- Repeat with the same geometry and orientation. Keep fan, speed, layer height, walls, and enclosure state fixed unless that is the one variable under test.
- Repeat the winning setting once, then confirm it on the real part. One lucky tower is not yet a stable production fix.
Fixes mapped to the evidence
- Dirty nozzle or material near the heater block: stop and correct maintenance or leakage before resuming profile tests.
- Exposed-spool symptoms: condition the filament exactly as its maker specifies, protect it after drying, and rerun the saved baseline.
- Fine hairs with otherwise clean extrusion: test one supported temperature step, then one travel-path change.
- Travel-heavy geometry only: reduce open crossings through orientation or documented slicer controls before adding large retraction.
- Hairs plus restart dots or gaps: inspect seam, wipe, pressure, and retraction as one restart-quality branch.
- Several defects at once: stop tuning the string count and restore the broader printer and material baseline.
Common fixes that create a different problem
- Dropping temperature far below the supported range: fewer hairs do not compensate for weak layers or incomplete flow.
- Copying a large retraction distance from another printer: drive path and hotend limits are machine-specific.
- Opening the enclosure or adding a strong draft: this changes the ASA warping and bonding environment instead of isolating stringing.
- Changing five slicer values together: the result cannot identify the cause and may fail on the next model.
- Using a flame as the main repair: it can deform the part, ignite nearby material, and hides rather than diagnoses the process.
What to do next
If the same spool becomes cleaner after proper conditioning, move to the ASA storage and moisture guide for prevention. If strands disappear but corners lift, continue with ASA warping. If strings end in repeatable dots, use the blobs and zits diagnostic. If the issue crosses several materials, use the general stringing guide to inspect the printer-wide branch.
Sources and scope
- Prusa Knowledge Base: Stringing and oozing — current guidance on nozzle residue, temperature, retraction, travel controls, and moisture.
- Prusa Knowledge Base: ASA — ASA enclosure, ventilation, temperature, warping, and partial-hygroscopicity context.
- Bambu Lab Wiki: Filament Drying Recommendations — a manufacturer-specific drying reference; use the instructions for the exact filament and drying equipment in hand.
This page is a diagnostic sequence, not a universal temperature or retraction profile. Printer design, hotend, nozzle, filament formulation, color, speed, and part geometry all change the valid operating window.