# PETG stringing: choose the next test from the evidence

[Read as HTML](<https://letitsee.com/guides/petg-stringing>)

Fine strands between separate features can be stringing, but the pattern alone cannot tell whether the cause is a changed profile, nozzle residue, the spool, travel behavior, or temperature and retraction settings. The most useful first check depends on what changed and what is visible. If a custom profile was recently edited, return to a saved known-good printer and PETG preset first. If there is obvious residue or a recent hotend change, follow the exact printer's maintenance procedure. If the problem follows one spool, compare a known-good spool under the same profile. Only when the printer is under its documented preset and the basic checks do not explain the result should you run a manufacturer-documented single-parameter test. No universal temperature or retraction value applies across printers and extruders.

## Follow the branch supported by what changed

Use a completed, cooled stringing test or a finished print with distinct travel gaps. Before changing anything, note whether the defect began after a custom-profile edit, a nozzle or hotend change, or a new spool. If you see a fault, leakage, or damaged part, stop and use the model's service instructions. Otherwise, use the first matching row below; each comparison changes what you should check next.

| What you know | First check | What result changes next |
| --- | --- | --- |
| Custom PETG settings changed before stringing began. | Record or save the current profile, restore the last known-good preset recommended for this printer and PETG, and repeat the same test with the same spool. | If strands decrease, one or more custom settings likely contributed, but the test does not identify which. Keep the preset as the comparison baseline; test only one manufacturer-documented parameter afterward if needed. |
| Residue is visibly stuck to the nozzle, or the hotend was recently changed. | Start with the exact model's inspection or maintenance procedure and follow its required shutdown and temperature steps. Do not improvise a cleaning method or infer internal assembly from the print photo. | If the documented maintenance removes visible residue and the next identical print improves, residue may have contributed. If there is leakage, damage, or a temperature fault, stop and contact the manufacturer; do not tune around a possible hardware fault. |
| The issue appears with one spool, and a known-good spool is available. | Keep the printer, model, profile, orientation, and travel settings fixed; compare the known-good spool under the same conditions. | If the pattern changes with the spool, spool-related differences become more plausible, but that does not prove moisture. If both behave similarly, the spool alone is a weaker explanation. |
| The issue persists under the maker's preset, with no visible residue or recent hardware fault. | Use a manufacturer-documented test for one parameter, such as the printer's prescribed temperature or retraction test. Keep other conditions fixed and record the exact values and result. | If the same strands reduce, the tested parameter affected this sample; confirm with a repeat before treating it as a stable setting. If not, stop broad setting changes and review the travel pattern, profile compatibility, spool, or manufacturer diagnostics. |

## Read the before-and-after sample carefully

Photograph the whole test and a close-up of the strands between features. Report whether hairs are distributed across many travel moves, concentrated at start or stop points, or accompanied by blobs and rough extrusion. Include the printer model and extruder, PETG product and spool, slicer preset, recent changes, and exact settings in text. A still can compare strand location and amount, but it cannot read the slicer, measure moisture, or establish that the hotend is assembled correctly.

Hypothetical A/B example: A PETG stringing tower printed after custom retraction and temperature edits has hairs between every pair of posts. B, using the same tower, spool, orientation, and printer with the saved manufacturer PETG preset restored, has fewer hairs. Decision: treat the custom profile as a likely contributor and keep the preset as baseline. If strands remain, test one documented parameter on another tower rather than changing temperature and retraction together. This illustrates the decision path and is not a physical test result.

## Use camera capture only for repeated visual comparisons

For one finished print, manually attach its photo; no camera setup is needed. If you are comparing multiple completed tests and an MCP camera session is already available, request a fresh still after each print has cooled. Keep exact profile values, spool history, and changes in text. The camera provides still images on request; it does not monitor a running job, read slicer files, or adjust printer controls.

## Prompt to adapt

> Use the manually attached photo, or request a fresh still of each completed, cooled sample if an MCP camera session is available. Printer/model and extruder: [ ]. PETG product and spool: [ ]. Slicer preset/version: [ ]. Was a custom profile changed? [ ]. Visible nozzle residue or recent hotend work? [ ]. Baseline test and settings: [ ]. Comparison test and its one documented change: [ ]. First describe where hairs, blobs, or roughness appear and whether they changed. Which decision-table branch matches the facts? State the next check and what result would change the branch. Do not assume moisture or propose universal temperature/retraction values.

## Source documentation

- [Prusa Knowledge Base: Stringing and oozing](<https://help.prusa3d.com/article/stringing-and-oozing_1805>)

## Connect your source

Add https://letitsee.com/mcp using remote MCP, Streamable HTTP, OAuth, and image results. Sign in with the same account and choose your source. [Use a phone camera with an MCP assistant](<https://letitsee.com/guides/phone-camera-mcp>) or [Use a webcam with an MCP assistant](<https://letitsee.com/guides/webcam-mcp>) cover setup and browser requirements.

## Set up without starting a capture

[Set up your MCP client](https://letitsee.com/for-agents) with the full tool reference. The separate [capture page](https://letitsee.com/live) can replace the active capture page for your account. It does not take a photo by itself.

## Related guides

- [3D print calibration log: compare one test at a time](<https://letitsee.com/guides/3d-print-calibration>)
- [3D print first layer not sticking? Check gaps and ridges](<https://letitsee.com/guides/3d-print-first-layer>)

[All camera and screen guides](https://letitsee.com/guides)