PETG Stringing: How to Eliminate Messy Strings When Printing With PETG Filament

PETG filament has become a popular material for 3D printing due to its strength, durability, and ease of printing. However, PETG is also prone to stringing, which can leave thin wispy strands of plastic detracting from your print’s appearance.

In this guide, we’ll explain what causes PETG stringing and provide fixes to avoid stringy prints. With the right settings dialed in, you can enjoy PETG’s benefits while eliminating those bothersome strings.

What Causes PETG Filament to String?

PETG (polyethylene terephthalate glycol-modified) is hygroscopic, meaning it absorbs moisture from the air. When this moisture-containing filament gets melted and extruded from the hot nozzle, it tends to produce more oozing and stringing versus materials like PLA and ABS.

Here are some of the main causes of stringing specific to PETG:

• Excessive moisture – PETG filament absorbs atmospheric humidity. Higher moisture content increases stringing.
• High temperature – Printing at the upper end of PETG’s recommended temp (240°C – 250°C) enhances stringing.
• Low retraction – Insufficient retraction distance allows molten filament to ooze during travel moves.
• Slow retraction – Fast retraction better prevents stringing versus slow pullback.
• Poor cooling – Lack of part cooling can allow extruded PETG to remain soft and sticky.

Most PETG stringing can be remedied with adjusted slice settings along with proper environmental conditions.

Ways to Reduce PETG Stringing

Here are the most effective methods for reducing stringing when 3D printing with PETG filament:

Dry PETG Filament

Moisture is PETG’s worst enemy when it comes to stringing. Before printing, thoroughly dry PETG per the manufacturer’s guidelines, usually 3-6 hours at 50°C-60°C. Some spools even come pre-dried.

Lower Nozzle Temperature

Printing at the low end of PETG’s optimal nozzle temp range between 230°C and 240°C can help reduce stringing versus printing hotter.

Increase Retraction Distance

A higher retraction distance like 6-8mm helps prevent stringing by fully pulling molten filament up into the cooled portion of the hot end.

Use Faster Retraction Speeds

Retracting at speeds of 40-70mm/sec allows filament to snap off cleanly rather than slowly oozing out.

Add a Filament Wipe

Wiping the nozzle over an infill area or priming tower while retracting cuts loose strings before they happen.

Optimize Cooling

Proper cooling, especially for small features, allows each layer to solidify quickly preventing further oozing. Cooling fans help.

Slow Down Small Layer Moves

Moving slower on intricate layers gives filament less time to ooze while also improving cooling.

With the right combination of drying, temperatures, retraction, cooling, and speed, PETG stringing can be reduced significantly or even eliminated.

PETG Stringing Settings in Cura

For those using Cura, here are the key slice settings to adjust to minimize PETG stringing:

Filament > Filament Temperature: 230-240°C

Lower temperatures reduce ooze.

Filament > Cooling: Enable

Keep cooling fan active to solidify layers faster.

Filament > Retraction: 6-8mm

Higher retraction distance prevents ooze.

Filament > Retraction Speed: 40-70mm/sec

Faster retraction minimizes stringing.

Travel > Combing Mode: All

Avoids strings by only retracting when crossing gaps.

Travel > Z Hop When Retracted: Checkbox

Z hop lifts nozzle while retracting to avoid dragging strings.

Save profiles for PETG with these settings dialed in to consistently reduce stringing.

PETG Printing Tips to Minimize Stringing

Beyond slicer settings, here are some additional PETG printing tips to further combat stringing:

• Store PETG filament in an airtight container with desiccant when not printing.
• Dry PETG per manufacturer recommendations before long prints to lower moisture.
• Use an enclosure to maintain chamber temperature and prevent drafts.
• Minimize traveled distance over printed parts to reduce string opportunities.
• Adjust slicer settings for each specific PETG brand and color.
• Slow down for small layer details prone to stringing issues.
• Clean nozzle before starting PETG prints if switching from other filament types.
• Replace nozzle periodically as wear widens tips increasing stringing over time.

Take your time dialing in the optimal settings for each PETG filament brand to achieve clean, string-free prints. Minor tweaks can make a big difference.

Advanced PETG Anti-Stringing Techniques

For more extreme cases, consider these advanced techniques:

Clean Nozzle Frequently – Wipe away charred PETG buildup in the nozzle hole using cleaning filament.

All-Metal Hot End – Upgrade to an all-metal hot end capable of 260°C+ for cleaner high-temp PETG extrusion.

Direct Drive – Converts to direct drive feed to flex filament less, reducing stringing.

Linear Advance – Uses firmware to dynamically adjust pressure when starting/stopping flow.

Conical Nozzles – Special nozzles with tapered tips minimize stringing.

Exotic Hot Ends – Next-gen hot ends like CopperheadTM and Biome completely wipe nozzles internally between layers.

While more involved modifications, these hot end and extruder upgrades can eliminate stringing for those printing primarily with PETG.

Wrapping Up PETG Stringing Solutions

PETG filament’s strength and ease of printing make it a go-to material for many 3D printing applications. However, PETG’s tendency to string can detract from an otherwise perfect print.

Thankfully, with the proper filament drying, temperature, retraction, speed, and cooling settings dialed in, PETG’s stringing habit can be tamed. Finding the right balance for your specific machine may require some trial and error. Additional measures like nozzle cleaning and upgrades can also banish strings for good.

While PETG may never be as string-free as PLA, a few smart tweaks go a long way. Before you know it, you’ll be churning out professional-quality PETG prints minus the messy strings. So don’t abandon PETG just yet. With our guide, you’ll develop the PETG prowess to finally win the battle against stringing.