The impact-toughened PETG variant · 11.6 kJ/m² Charpy notched (~4.5× plain PETG's 2.6) with a slightly lower datasheet tensile that real-world durability more than makes up for. For drops, snap-fits, and vibrating parts where plain PETG cracks. Cross-checked against the manufacturer's PolyMax PETG TDS V5.3.
PETG Plus 3D printing service · UK · quoted in 6 hours.
The toughness wedge over plain PETG · 4× Charpy impact, near-isotropic stiffness, same chemistry family.
Four quick visuals. Start with which material to pick and where PETG+ works; the engineering detail is at the end if you want it.
A fraction of the ethylene glycol monomer is replaced with cyclohexanedimethanol (CHDM), which breaks the crystal symmetry. The result: same PET chemistry, no warping, food-bottle heritage.
PETG+ trades elongation for impact toughness · 5.22% strain at break (vs plain PETG's 8.4%) but ~4.5× the notched Charpy (11.6 vs 2.6 kJ/m²). For raw toughness above PETG+: ABS at 18.0 kJ/m² remains higher.
"James handled the 3D printing for a functional heat resistant component we needed in batch production. He helped dial in the prototype first with their design service, then produced the final batch with really consistent results. Super fast 3D print turnaround and great quality across all the 3D printed parts. Will 100% be coming back."
"We needed a sit-in F1-car for an exhibition to showcase our new racing game. 3D Printing Express took our CAD, optimised it for strength and weight as we had no idea how it all worked! Turned out beautifully. They colour matched the finish and was looking like the real deal. On show day the cockpit ran non-stop, adults and kids jumped in. Multiple visitors asked who built it."
"We ordered a batch of 100 PA-12 parts from 3D Printing Express and could not be happier. Every part arrived consistent, dimensionally accurate, and ready for use straight from the box. The PA-12 gave us the strength and stability we needed for functional testing, with minimal post-processing required. Delivery was on time, communication was excellent, and their QC clearly made a difference."
The headline wedge over plain PETG (2.6 kJ/m²) · ~4.5× the notched impact. Drop survival and snap-fit cycling without crack initiation. ~64% of ABS (18 kJ/m²).
Datasheet tensile is below plain PETG (37.9 vs 50.8 MPa) but real-world durability is the premium-grade advantage · PETG+ is the tougher functional choice (~4.5× notched Charpy). Pick PETG+ for impact, plain PETG for cosmetic / cost-led work.
20% lower than plain PETG (2117 MPa) · softer in-hand. Near-isotropic stiffness (XY/Z 1.05×) · prints with less direction-dependent behaviour than plain PETG.
Within 2°C of plain PETG's 78°C · same service-temperature envelope. Sustained service up to ~70°C, engine bay / autoclave still wrong material. Same drying protocol as plain PETG.
PETG+ earns its place when impact resistance, drop survival, and cyclic-load durability matter · the toughened PETG variant for parts that face real-world abuse without the heat ceiling or print difficulty of ABS.
PETG+ keeps plain PETG's heat envelope and chemical limits · it only adds impact toughness. The toughness wedge doesn't help with heat, chemistry, or stiffness-critical applications. Pick a different filament if any of these apply.
PETG+ at 11.6 kJ/m² Charpy is the right pick when the part will be dropped or handled. Field-tool housings, prosumer device shells, ruggedised consumer electronics enclosures · plain PETG cracks on workshop-floor drops, PETG+ dents.
Snap-fits that open and close hundreds of times benefit from the toughened blend's resistance to fatigue crack growth at the hinge root. Latched enclosures, access panels, battery-bay covers, openable lids for service access.
Vibrating fixtures see cyclic loads that initiate cracks at stress risers in plain PETG. PETG+'s toughened matrix resists fatigue crack growth and survives more cycles before failure · drone landing-frame mounts, robotics arm brackets, motor mounts in shaker-table fixtures.
Workshop splash guards that see tool drops, machine guards near moving equipment, hand-held pendants that get knocked · the toughened matrix dents on impact rather than cracking, keeping the part in service while plain PETG would need replacement.
The three commodity thermoplastics engineers compare when impact matters. Plain PETG wins on raw stiffness and cost. ABS wins on raw impact and heat. PETG+ sits between them · ~4.5× plain PETG notched Charpy; datasheet stiffness/tensile read a little lower but real-world durability is the premium-grade advantage, no heated chamber needed.
All values from manufacturer Technical Data Sheets V5.4 EN · injection-moulded ISO test specimens (ISO 527 tensile + elongation, ISO 75 HDT, ISO 179 Charpy notched). The chart shows where each material wins · PETG's wedge is ductility plus water/food-contact heritage, not raw strength or heat.
| Property | PETG+ (here) | Plain PETG | ABS / ASA |
|---|---|---|---|
| Charpy notched impact | 11.6 kJ/m² | 2.6 kJ/m² | 18.0 kJ/m² |
| Tensile strength XY | 37.9 MPa | 50.8 MPa | 33.4 MPa |
| Stiffness (Young's modulus XY) | 1684 MPa | 2117 MPa | 2247 MPa |
| Elongation at break XY | 5.22% | 8.4% | 17.9% |
| Heat deflection (HDT 0.45) | 76°C | 78°C | 100°C |
| Glass transition (Tg) | 79°C | 81°C | 101°C |
| Density | 1.25 g/cm³ | 1.25 g/cm³ | 1.04 g/cm³ |
| Drop / snap-fit cycling | Yes · ~4.5× plain PETG Charpy uplift | Cracks at hinge root / drop edge | Yes · highest raw impact |
| Water-contact service | Yes · same PET-glycol backbone | Yes · proven in hydroponic / irrigation | Yes · low water absorption |
| Outdoor / UV (years) | 6-12 months uncoated | 6-12 months uncoated | ASA grade: 5+ years |
| Print difficulty | Moderate · drying required | Moderate · same drying | Hardest · chamber needed |
| Cost per kg (filament) | £30-45 | £25-40 | £30-45 |
| Best for | Water-contact, food-adjacent prototypes, signage, ductile enclosures | Visual prototypes, props, indoor cosmetic | Heat / outdoor (ASA) / impact-loaded parts |
This is 3DPE's standard process for PETG+ · the equipment and the dried-filament discipline are included, no surcharge. Slicer profile and orientation are tuned per part at quote stage.
File or sketch in. Tell us colour, finish, water / food-adjacent or structural use.
Reviewed inside 24 hours · per-unit cost + colour confirmation.
Wall thickness, overhang, support strategy, ductility-vs-load fit flagged before print.
Filament dried at 65°C for 6 hours (mandatory for PETG) · calibrated machine · stock or custom-RAL colour matched.
Sand to spec · 2K spray paint if needed · food-safe epoxy overcoat where requested.
Tracked UK courier, tracking number sent the moment it leaves.
Lead times start when CAD is signed off and colour is confirmed · CAD round-trips on rev requests can extend the clock. Custom RAL colour matching can add 1-2 days for filament procurement. Food-safe epoxy overcoat adds 24h for cure.
Production batch of water-contact irrigation fittings printed in standard PETG · stock-colour translucent grade, cosmetic-quality glossy finish out of process. PET-backbone hydrolytic stability proven in cold-to-warm water service. Indoor / outdoor commercial-grade use case · the part profile PETG was designed for.
PETG is polyethylene terephthalate, glycol-modified · an amorphous copolyester where a fraction of the ethylene glycol monomer is replaced with cyclohexanedimethanol (CHDM). The base PET polymer is the same chemistry used in plastic water bottles, food packaging, and polyester fibre; the CHDM modification breaks the crystal symmetry and lets PETG print on FDM without the warping problems of crystalline PET. Tensile strength 37.9 MPa XY (ISO 527) and Young's modulus 1684 MPa on the datasheet read below plain PETG (50.8 MPa / 2117 MPa), but that understates real-world behaviour · PETG+ is the impact-toughened premium grade and in functional prints it is the more durable choice, with notched Charpy 11.6 kJ/m² (~4.5× plain PETG's 2.6). HDT 76°C at 0.45 MPa (ISO 75), elongation at break 5.22% (vs plain PETG's 8.4% · the trade for crack-bridging toughness). Density 1.25 g/cm³ (matches plain PETG). The PETG matrix shares plain PETG's PET-backbone food-contact chemistry; the printed FDM grade is not food-contact certified.
"PETG is the material I reach for when the brief includes water, food-adjacent service, or mild outdoor exposure · or when the customer dropped a PLA prototype and watched it snap. It's the ductile commodity that does most of what people think PLA does, plus a meaningful jump in heat tolerance (76°C vs 60°C HDT) and the PET-backbone water story. The two catches are mandatory pre-print drying (PETG is hygroscopic · we condition every spool at 65°C for 6 hours) and the moderate UV ceiling. For multi-year outdoor we still recommend ASA."
Three questions worth answering before specifying PETG · where the polymer comes from, why it's hygroscopic, and where the 75°C HDT cliff really matters.
Base PET is the most-produced thermoplastic on Earth · food bottles, packaging, polyester fibre. Glycol modification (CHDM replaces some ethylene glycol) breaks the crystal symmetry, prevents crystallisation, and makes PET 3D-printable on FDM without the warping of crystalline PET.
PETG absorbs water from humid air, saturating at ~0.54% per the manufacturer TDS. Wet PETG prints stringy, milky, brittle. The fix is straightforward · pre-print drying at 65°C for 6 hours (manufacturer setting). We do this on every spool before the bed.
PETG is polyethylene terephthalate, glycol-modified · an amorphous copolyester. The base PET chemistry is the same polymer used in plastic water bottles, polyester clothing, and most food packaging. The modification: a fraction of the ethylene glycol monomer in the backbone is replaced with cyclohexanedimethanol (CHDM). That substitution breaks the crystal symmetry of the backbone and prevents the polymer from crystallising.
The chemical formula shifts from PET's -[O-CH₂-CH₂-O-CO-C₆H₄-CO]-n to PETG, where some of the -CH₂-CH₂- ethylene-glycol units are replaced with the larger -CH₂-C₆H₁₀-CH₂- CHDM rings. The result is a glass-clear, amorphous thermoplastic that prints beautifully on FDM without the warping problems of crystalline PET. This matters for three reasons: amorphous structure means no crystallisation shrinkage on cooling (large flat parts stay flat); PET backbone heritage gives PETG real chemical and moisture resistance; and the food-contact compliance of base PET (FDA 21 CFR 177.1630) carries through the chemistry for certified food-grade variants.
PETG absorbs moisture from humid air · equilibrium water absorption is 0.54% per the manufacturer TDS, reached over days to weeks in 60% RH workshop conditions. The hydroxyl groups introduced by the glycol modification are mildly polar, which is why PETG holds onto water more than purely non-polar polymers like polyethylene.
Wet PETG prints badly. Water in the filament flashes to steam at the nozzle (which sits well above water's boiling point), producing visible stringing, milky surface finish, and reduced layer adhesion. The brittleness of wet-printed PETG parts is the most common reason for "PETG broke at the layer line" complaints. The fix is straightforward · pre-print drying at 65°C for 6 hours (per the manufacturer's recommended setting) and storing the spool in a sealed dry-box with desiccant. We run every PETG spool through a filament drier before the bed; a maker skipping this step gets noticeably worse parts.
PETG's glass transition temperature (Tg) sits at 81°C (DSC, 10°C/min). Below Tg the polymer chains are locked in the amorphous network and the part holds its shape. Above Tg the chains gain mobility · stiffness collapses, the part softens, and any residual stress from printing relaxes into creep. Heat deflection temperature (HDT) at 0.45 MPa load is 76°C, dropping to 72°C at 1.8 MPa load. Vicat softening at 82°C. For sustained service the practical ceiling is ~70°C · a PETG part in a car dashboard in summer, near an engine, or pressed against a radiator will creep and deform.
Steam autoclave at 121°C is well above HDT · parts deform. For sterilisation, ethylene oxide or IPA wipe-down work for PETG; dry-heat sterilisation below 70°C also works. For repeated steam autoclave service specify PEEK or PPSU. For sustained warm-service parts (engine bay, exhaust-adjacent, oven-adjacent) choose ABS or ASA (HDT 100°C class) or PA12-CF (HDT 130°C+ class).
Values measured to the ISO standards cited in the right-hand column, on the manufacturer's own injection-moulded test specimens · directly comparable to other engineering thermoplastics.
| Property | XY · print plane | Z · build axis | Unit | Standard |
|---|---|---|---|---|
| Mechanical | ||||
| Tensile strength | 37.9 | 29.4 | MPa | ISO 527 |
| Young's modulus | 1684 | 1603 | MPa | ISO 527 |
| Elongation at break | 5.22 | 3.10 | % | ISO 527 |
| Flexural strength (XY) | 58.3 | MPa | ISO 178 | |
| Flexural modulus (XY) | 1068 | MPa | ISO 178 | |
| Charpy impact (notched, XY) | 11.6 | kJ/m² | ISO 179 · PolyMax PETG | |
| Thermal | ||||
| Heat deflection (HDT @ 0.45 MPa) | 76 | °C | ISO 75 | |
| Heat deflection (HDT @ 1.8 MPa) | 72 | °C | ISO 75 | |
| Glass transition temperature (Tg) | 79 | °C | DSC, 10°C/min | |
| Vicat softening temperature | 82 | °C | ISO 306 | |
| Physical | ||||
| Density | 1.25 | g/cm³ @ 23°C | ISO 1183 | |
| Equilibrium water absorption | 0.542 | % | manufacturer test | |
| Melt index | 10.8 | g/10min | 240°C, 2.16kg | |
| Light transmission | 90 | % | GB/T 2410 | |
| Tensile anisotropy ratio | 1.29× | XY/Z | derived from ISO 527 | |
| Chemical resistance · manufacturer-rated | ||||
| Weak acids | Good | · | manufacturer TDS | |
| Strong acids | Poor | · | manufacturer TDS | |
| Weak alkalis | Fair | · | manufacturer TDS | |
| Strong alkalis | Poor | · | manufacturer TDS | |
| Oils and grease | Good | · | manufacturer TDS | |
| Cosmetic / supply | ||||
| Stock colour range | 20+ colours (incl. translucent + clear grades) | · | workshop stock | |
| Custom RAL match | Yes (1-2 day procurement) | · | on request | |
| Finish grades available | Glossy as-printed, sanded, painted, translucent | · | workshop stock | |
| Food-contact base polymer | PET base · FDA 21 CFR 177.1630 compliant (printed grade NOT certified) | · | FDA regulation | |
PETG+'s anisotropy is mild (1.29× XY/Z · 37.9/29.4 MPa per TDS V5.4 · same envelope as plain PETG). For load-bearing PETG+ parts, favour XY-direction load paths.
PETG+'s elongation (5.22%) is lower than plain PETG (8.4%) but its notched Charpy (11.6 kJ/m²) is ~4.5× higher · the impact modifier trades give for crack-bridging, so in real-world functional use PETG+ is the tougher, more durable grade despite the lower datasheet tensile. Wall-thickness floors follow the Hubs / Protolabs Network FDM minimums (0.8 mm supported, 2.0 mm feature) · we DFM-check against your load case at quote stage.
45° is the slicer-default support threshold across every major FDM tool · PETG's slower cooling and stickier hot state typically holds long bridges (5 mm+ at print temperature) better than PLA. Exact threshold depends on cooling, geometry, and surface-finish tolerance · we DFM-check overhangs at quote stage and recommend orientation.
PETG's amorphous structure means no crystallisation shrinkage on cooling (good) but the lower stiffness means slightly more deflection during finishing (modest). Exact tolerance depends on part size, geometry, and calibration · we confirm achievable tolerance against your CAD at quote stage.
Removes 0.1-0.3 mm per surface · pre-paint prep or stand-alone hand-feel polish.
Wet PETG (the spool has been in humid air more than ~3 days) prints stringy, milky, and brittle. Pre-print drying is per the manufacturer's recommended setting · we run this on every spool before the bed.
PETG takes paint with adhesion-promoting primer (PETG resists direct paint adhesion more than PLA). Adds 0.05-0.15 mm per surface · sand to 800 grit, primer + topcoat · paint also acts as a UV barrier for outdoor service.
The real food-contact risk on FDM PETG isn't the polymer · it's bacteria in micro-gaps between layers. A food-safe epoxy overcoat (we use NSF-certified two-part) bridges the layer-line porosity and gives a continuous food-adjacent surface. Adds 0.05-0.1 mm per surface and 24 hours cure.
Every value on this page traces to an ISO test method · the manufacturer's V5.4 EN TDS, cross-checked against the PDF in-session. We don't quote derived numbers without naming the standard.
No offshore subcontracting. Files, prints, and couriers all stay in the UK · and we dry every PETG spool at 65°C for 6 hours before the bed, per the manufacturer's recommended setting.
Send three things: where the part lives (water, food-adjacent, outdoor, indoor), what it does (cosmetic / functional / load-bearing), and colour / finish. our team come back inside 24 hours · if PLA, ABS, ASA, or another material fits better, we say so.
our team review every brief before quote. No ticket queue, no account managers.
According to the PolyMax PETG TDS, PETG+ delivers a notched Charpy of 11.6 ± 0.8 kJ/m² (XY) per ISO 179 · ~4.5× plain PETG's 2.6 · at Tg 79 °C and HDT 76 °C @ 0.45 MPa.
Yes. We run a closed loop in our own workshop. Failed prints, purge, and support waste are collected, reground, and reprocessed here instead of going to landfill. That is standard on every PETG+ job, no surcharge.
PETG+ is a toughened PETG/PCTG blend. The headline difference is ~4.5× the notched Charpy impact (11.6 vs 2.6 kJ/m²). Datasheet tensile (37.9 MPa) and modulus (1684 MPa) read below plain PETG (50.8 / 2117), but real-world durability is the premium-grade advantage · we treat PETG+ as the tougher functional choice. Same chemistry family, same drying protocol (65°C / 6h), same printing window · no heated chamber. Pick PETG+ when impact survival matters (drop-tested parts, snap-fit cycling, vibrating fixtures); pick plain PETG for cosmetic or cost-led work.
The base PET polymer is FDA 21 CFR 177.1630 compliant for food contact in moulded and extruded form. Standard PETG is NOT certified for food contact · the certification applies to specific food-grade PETG variants, not to commodity FDM filaments. For a food-contact application 3DPE specifies a certified food-grade PETG variant and recommends a food-safe epoxy overcoat to seal FDM layer porosity (the real risk · bacteria can harbour in micro-gaps between print layers even when the polymer itself is food-safe). The honest answer: PETG is the right chemistry, but printed parts need certification + sealing for true food-contact service.
Genuinely yes for cold-to-warm water service. PETG has good hydrolytic stability and the base PET backbone is the same chemistry used in plastic water bottles. Suitable for hydroponic fittings, splash enclosures, water-tank brackets, and vases. Long-term sustained service above 60°C in hot water starts to degrade the polymer; for repeatable hot-water service specify PP or PEEK. Note: PETG itself absorbs moisture from humid air (0.54% equilibrium per TDS) · this affects print quality, not the waterproof-ness of a finished, dried part.
Moderate UV resistance · better than PLA, slightly better than ABS, not as good as ASA. The PET aromatic ring absorbs UV more stably than the aliphatic PLA backbone, which is why PET water bottles survive outdoor warehousing. For 6 to 12 months UK outdoor service uncoated PETG holds up reasonably (colour fade and surface micro-cracking begin around year 2). For multi-year outdoor service specify ASA or UV-stabilised PC. We use the phrase "moderate UV resistance" not "UV resistant".
Per the manufacturer TDS · GOOD against weak acids and oils/grease, POOR against strong acids and strong alkalis, FAIR against weak alkalis. Also dissolves partially in acetone and other ketones. For sustained chemical-service parts use PA12 or PP. Match your specific exposure below.
| Chemical / family | Resistance | Notes |
|---|---|---|
| Weak acids (acetic, citric, dilute organic) | Good | Manufacturer TDS rating · short-term storage |
| Strong acids (sulphuric, HCl, nitric) | Poor | Manufacturer TDS rating · polymer chain breakdown |
| Weak alkalis (dilute soap, mild bleach) | Fair | Manufacturer TDS rating · short-term only |
| Strong alkalis (caustic soda, ammonia) | Poor | Manufacturer TDS rating · ester bond hydrolysis |
| Oils and grease | Good | Manufacturer TDS rating · sustained contact OK |
| Cold water, sea water (cold) | Excellent | PET-backbone hydrolytic stability · proven in bottles |
| Hot water (sustained > 60°C) | Limited | Approaches HDT · hydrolysis accelerates over months |
| Steam autoclave (121°C) | Fails | Above HDT · parts deform · choose PEEK / PPSU |
| Detergents, soap (mild) | Good | Dishwasher-style detergents · short-cycle only (heat above 60°C is the limit) |
| Alcohols (IPA, ethanol, methanol) wipe | Good | Surface cleaning, no soak |
| Acetone, MEK (ketones) | Poor | Partial dissolution · industrial degreaser, nail polish remover |
| Toluene, xylene (aromatic hydrocarbons) | Poor | Degrades over time |
| Petrol, diesel (brief contact) | Limited | Brief OK · sustained attacks the polymer |
| Chlorinated solvents (DCM, chloroform) | Poor | Strong solvents · industrial use only, workshop hazards |
| Swimming pool chemistry (chlorine, bromine) | Limited | Short-term OK · sustained immersion attacks the polymer |
| UV exposure (UK outdoor) | Limited | 6-12 months uncoated · multi-year requires overcoat or ASA |
| Outdoor weathering (sheltered) | Good | Rain-tight under cover, hydroponic outdoor, garden irrigation |
| Food contact (base PET chemistry) | Excellent | FDA 21 CFR 177.1630 compliant base · printed grade needs certification + sealing for true food-contact |
First five rows are direct manufacturer TDS ratings. Remaining rows reflect industry-typical PETG behaviour and 3DPE workshop experience · brief contact is always more forgiving than sustained exposure. For sustained chemical service beyond water and oils, switch material to ABS, PA12, or PP depending on the exposure.
Much less than ABS, slightly more than PLA. PETG is amorphous · no crystallisation shrinkage on cooling. Bed adhesion on PC, textured PEI, or buildtak is generally good. Large flat PETG parts stay flat. The biggest print issue is wet filament producing stringing and brittle layer adhesion, not warping · this is why we dry every spool at 65°C for 6 hours before printing per the manufacturer's recommended drying setting.
PETG is hygroscopic · equilibrium water absorption is 0.54% (per TDS) and the filament approaches saturation over days to weeks in humid UK workshop air. Water in the filament flashes to steam at the nozzle, producing visible stringing, milky surface, and reduced layer adhesion. Pre-print drying at 65°C for 6 hours (manufacturer setting) is mandatory for production work. A DIY maker skipping this step produces noticeably worse parts; we run every spool through a drier before the bed.
Different tools. PETG wins on: ease of print (no chamber needed, low VOC), water and food-adjacent service, moderate UV. ABS wins on: heat (HDT 98°C vs PETG 75°C), impact (Charpy 18.0 vs 2.6 kJ/m² · 7× tougher), acetone-smoothability for finishing, lower density (1.04 vs 1.25 g/cm³ · 17% lighter parts). If the part sees impact loads or sustained heat above 60°C, choose ABS. If it sees water, mild outdoor, or food-adjacent service, choose PETG.
Not with common solvents. PETG resists most chemistry that would bond it (acetone partially dissolves but doesn't cleanly fuse like it does for ABS). Use 2-part epoxy for structural bonds · cyanoacrylate works but bonds are weaker than on PLA or ABS. Ultrasonic welding works well. For multi-part assemblies, mechanical fasteners with heat-set inserts (245°C iron temp) are the most reliable joint.
No. Steam autoclave at 121°C is above PETG's HDT (72°C at 1.8 MPa) · parts deform. Dry-heat sterilisation below 70°C, ethylene oxide, and IPA wipe-down all work for PETG. For repeated steam-autoclave service (medical, dental, lab equipment) specify PEEK or PPSU.
Tg sits at 79°C · above this PETG softens. HDT is 76°C at 0.45 MPa and 72°C at 1.8 MPa (per TDS). Vicat softening at 82°C. A PETG part in sustained service above 70°C will creep and slowly deform. PETG handles 60°C hot water short-term, won't survive an engine bay, and is the wrong material for anything near a radiator or in direct summer sun on a hot surface. For warm-service parts choose ABS or ASA (HDT 100°C class).
Filament cost is roughly £30-45/kg for stock-colour PETG+ · a 15-20% premium over plain PETG (£25-40/kg) for the toughened PCTG blend. Print conditions and print time are the same as plain PETG · the extra cost is specialty-blend pricing. Worth it when impact survival is the design requirement, not for parts that never see impact. Send the brief and we'll quote PETG+ vs plain PETG side-by-side.
You'll hear back from our team within 24 hours · with material-fit check (PETG+ vs plain PETG vs ABS), drying/lead-time confirmation, and impact-load assessment.