{"id":1160,"date":"2026-08-18T07:02:26","date_gmt":"2026-08-18T07:02:26","guid":{"rendered":"https:\/\/ever-powers.com\/?p=1160"},"modified":"2026-08-18T07:10:02","modified_gmt":"2026-08-18T07:10:02","slug":"petg-vs-pet-cosmetic-bottle-blow-molding-machine","status":"publish","type":"post","link":"https:\/\/ever-powers.com\/en_ca\/application\/petg-vs-pet-cosmetic-bottle-blow-molding-machine\/","title":{"rendered":"PETG vs PET for Cosmetic Bottles: Resin Selection and Blow Molding Machine Configuration Guide"},"content":{"rendered":"

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Cosmetic bottle manufacturers choosing between PET and PETG face a decision that goes beyond material cost. The resin choice determines preform geometry, conditioning station temperature profile, allowable stretch ratio, and ultimately which machine platform \u2014 multi-cavity ES or single-cavity FS \u2014 can actually deliver the dimensional tolerances the container design requires. This guide works through the processing differences of both materials from a machine-configuration standpoint, with direct reference to the parameters that drive rejection rates on a production line.<\/p>\n

\"Cosmetic<\/p>\n

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Why PET and PETG Process Differently in an Injection Stretch Blow Molding Machine<\/h2>\n<\/div>\n

Both PET (polyethylene terephthalate) and PETG (polyethylene terephthalate glycol-modified) are amorphous when injection-molded into preforms, and both need to be conditioned above their glass transition temperature (Tg) before biaxial orientation is possible. That is where the similarity ends.<\/p>\n

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Glass Transition Temperatures & Processing Windows<\/p>\n\n\n\n\n\n\n
Material<\/th>\nTg (\u00b0C)<\/th>\nOptimal Blow Window (\u00b0C)<\/th>\nCrystallization Risk<\/th>\n<\/tr>\n<\/thead>\n
PET (bottle-grade, IV 0.72\u20130.84 dL\/g)<\/td>\n72\u201376 \u00b0C<\/td>\n95\u2013115 \u00b0C<\/td>\nHigh above 120 \u00b0C<\/span><\/td>\n<\/tr>\n
PETG (copolymer, IV 0.76\u20130.80 dL\/g)<\/td>\n78\u201383 \u00b0C<\/td>\n80\u201395 \u00b0C<\/td>\nNone \u2014 amorphous<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

PETG’s higher Tg means the conditioning station must bring the preform to a higher absolute temperature before the material becomes sufficiently compliant for stretching. But its complete absence of crystallization means there is no upper temperature boundary where the material becomes hazy or loses orientation memory. On a PET preform, pushing conditioning temperature above approximately 120\u2013125 \u00b0C triggers strain-induced crystallization in the shoulder zone before the stretch rod contacts the preform \u2014 producing whitish opacity that cannot be recovered in the blow cycle.<\/p>\n

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Practical consequence:<\/strong> PETG conditioning is more forgiving in the upper temperature range but demands precise floor management. PET conditioning demands precise ceiling<\/em> management. Confusing the two is the most common machine setup error on a cosmetic bottle line switching materials.<\/p>\n<\/div>\n

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Stretch Ratio Constraints: PET vs PETG in Cosmetic Bottle Geometries<\/h2>\n<\/div>\n

Injection stretch blow molding achieves its mechanical and optical properties through biaxial orientation \u2014 the simultaneous axial stretch (from the stretch rod) and hoop stretch (from blow pressure). The ratio of final container dimensions to preform dimensions defines the stretch ratio.<\/p>\n

<\/p>\n\n\n\n
\n
Axial Stretch Ratio (SRa<\/sub>)<\/div>\n
Final container height \u00f7 preform body length<\/div>\n<\/td>\n
\n
Hoop Stretch Ratio (SRh<\/sub>)<\/div>\n
Final container body diameter \u00f7 preform body diameter<\/div>\n<\/td>\n
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Planar Stretch Ratio<\/div>\n
SRa<\/sub> \u00d7 SRh<\/sub> \u2014 the combined biaxial orientation index<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

For standard PET cosmetic bottles, the recommended planar stretch ratio is 8\u201312<\/strong>. Below 8, the material does not achieve sufficient biaxial orientation for the optical clarity and top-load resistance the container needs. Above 14\u201316, micro-crazing can occur at stress concentration points \u2014 typically at the heel radius and the shoulder transition.<\/p>\n

PETG tolerates a narrower planar stretch ratio: typically 6\u201310<\/strong>. Because PETG does not crystallize under strain, it cannot develop the strain-hardening behavior that PET relies on to resist over-stretch at high ratios. Designing a PETG cosmetic bottle with a planar stretch ratio above 10 produces uncontrolled wall thinning in the panel zones, which shows as visible soft spots under shelf lighting.<\/p>\n

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Machine implication:<\/strong> A serum bottle with a 30mm body diameter and 180mm body height has an axial stretch ratio of approximately 5.5\u20136.0. Achieving this on PETG requires extended conditioning dwell time \u2014 adjustable from 5 to 20 seconds on the HGA series \u2014 to ensure the material is compliant enough to accept full rod travel without tearing.<\/p>\n<\/div>\n

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Surface Finish Requirements and How Each Material Responds<\/h2>\n<\/div>\n

In cosmetic packaging, the container surface is part of the product presentation. The relevant defect categories differ between PET and PETG, and diagnosing them incorrectly leads to machine adjustments that solve nothing.<\/p>\n

<\/p>\n\n\n\n
\n
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PET Defect Profile<\/div>\n
\n
\u26a0 Weld Line Visibility<\/div>\n
Gate marks on PET preforms are unavoidable. On transparent cosmetic bottles, even low-stress weld lines below the fill waterline constitute visual rejects. Gate position<\/em> is the control \u2014 mold design stage, not machine setting.<\/div>\n<\/div>\n
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\u26a0 Birefringent Banding<\/div>\n
Stress-induced optical banding in PET panels is caused by circumferentially non-uniform conditioning. Controlled via the 10-zone independent IR lamp output map on the HGA ES-platform conditioning station.<\/div>\n<\/div>\n
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\u2716 Crystalline Haze (Stress Whitening)<\/div>\n
Triggered above ~120 \u00b0C in the shoulder zone. Appears as permanent opaque white haze. Prevention: set shoulder-zone lamp output 8\u201312% below body zone. Irrecoverable once formed \u2014 must be caught in setup, not QC.<\/div>\n<\/div>\n<\/div>\n<\/td>\n
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PETG Defect Profile<\/div>\n
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\u26a0 Weld Line Stress Cracking<\/div>\n
PETG has lower stress crack resistance than oriented PET. A weld line in a stress concentration zone (panel corner, shoulder transition) is a potential structural failure point, not merely a cosmetic defect. Gate location must account for weld line position.<\/div>\n<\/div>\n
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\u26a0 Scratch Sensitivity<\/div>\n
PETG surface hardness (pencil hardness B\u2013HB) is lower than oriented PET (H\u20132H post-orientation). Transport handling and label application lines require softer contact surfaces for PETG cosmetic containers.<\/div>\n<\/div>\n
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\u26a0 Gate Area Haze<\/div>\n
PETG does not benefit from strain-induced crystallization to improve gate clarity. Haze at the gate zone originates in the injection molding conditions \u2014 a preform supplier quality issue, not a blow machine parameter. Verify in incoming preform inspection.<\/div>\n<\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Machine Platform Selection: ES Multi-Cavity vs FS Single-Cavity<\/h2>\n<\/div>\n

The choice between the ES and FS platforms is driven by two primary factors: container geometry and required output. Below is the decision logic for each.<\/p>\n

ES Platform (2\u20136 Cavity) \u2014 PET & Standard PETG<\/h3>\n

The ES platform covers 2-cavity through 6-cavity configurations. The HGA.ES-2C114.3 handles PET cosmetic containers up to 1,000 ml; the HGA.ES-6C114 reaches 5,400 bph on containers up to 1,500 ml.<\/p>\n

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Specify ES Platform When:<\/div>\n\n\n\n\n\n\n\n
\u2713<\/span>Container cross-section is circular or mildly oval (aspect ratio \u2264 1.6:1)<\/td>\n<\/tr>\n
\u2713<\/span>Neck finish is standard (28mm PCO, 38mm, 48mm, or other commercial sizes)<\/td>\n<\/tr>\n
\u2713<\/span>Material is PET or PETG in standard preform geometries<\/td>\n<\/tr>\n
\u2713<\/span>Output requirement exceeds 1,500 bph \u2014 requiring 3 or more cavities<\/td>\n<\/tr>\n
\u2713<\/span>Container height is within the clamping envelope (up to 330mm on ES-4C114.3)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

FS Platform (Single-Cavity) \u2014 PETG Irregular Geometries<\/h3>\n

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Specify FS Platform When:<\/div>\n\n\n\n\n\n\n\n
\u25b6<\/span>Container cross-section is non-circular: oval with aspect ratio > 1.6:1, multi-faceted, or asymmetric<\/td>\n<\/tr>\n
\u25b6<\/span>Container has an angled or offset neck relative to the container centroid<\/td>\n<\/tr>\n
\u25b6<\/span>Material is PETG in a high-clarity premium application with irregular geometry<\/td>\n<\/tr>\n
\u25b6<\/span>Output requirement is below 700 bph<\/td>\n<\/tr>\n
\u25b6<\/span>Container body diameter exceeds 190mm (FS-1CG220 and FS-2CG220 only)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

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Platform Comparison \u2014 HGA Cosmetic Machine Range<\/p>\n\n\n\n\n\n\n
Platform<\/th>\nMax Cavities<\/th>\nMax Output (bph)<\/th>\nGeometry Support<\/th>\nRecommended Resin<\/th>\n<\/tr>\n<\/thead>\n
HGA.ES series<\/td>\n6<\/td>\n7,200<\/td>\nMild oval, standard round<\/td>\nPET, PETG (standard preforms)<\/td>\n<\/tr>\n
HGA.FS series<\/td>\n2<\/td>\n1,000<\/td>\nHigh-difficulty irregular<\/td>\nPETG, PC, PCTG<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Output penalty of choosing FS:<\/strong> A single-cavity FS-1CG150 runs at 700 bph on a 2,500 ml PETG container. The equivalent ES-2C150 reaches 1,800 bph on the same volume. Choosing the FS platform means accepting a 2.5\u00d7 output penalty<\/strong> \u2014 a production planning constraint that must be calculated before committing to a container design with high geometric complexity.<\/p>\n<\/div>\n

\"Process<\/p>\n

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Energy Consumption: PET vs PETG Conditioning Load<\/h2>\n<\/div>\n

Because PETG requires a higher conditioning temperature floor, the heating power demand per cycle is marginally higher for PETG production than for equivalent PET production on the same model. On an HGA.ES-2C114.3 machine (max heating power 50 kW, typical operating consumption 16 kW), the difference is approximately 10\u201315% higher heating element duty cycle<\/strong> for PETG compared to a standard PET cosmetic bottle preform \u2014 not enough to change the compressor or power supply specification, but enough to appear in the electricity cost calculation over a production year.<\/p>\n

Servo drive systems reduce cycle-to-cycle energy variation regardless of resin type. The HGA series servo motor drives cut total machine energy consumption by 30\u201340%<\/strong> versus hydraulic-drive equivalents. This saving applies equally to PET and PETG production runs.<\/p>\n

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Material Switching Between PET and PETG: What Changes on the Machine<\/h2>\n<\/div>\n

If a production line runs both PET and PETG cosmetic bottles on the same machine \u2014 a common configuration for personal care contract manufacturers \u2014 the changeover procedure involves three adjustments. No mechanical retrofit is required. The mold set remains the same.<\/p>\n

<\/p>\n\n\n\n
\n\n\n\n\n
\n
1<\/div>\n<\/td>\n
\n
Conditioning Station Temperature Profile<\/div>\n
PETG requires body zone lamps to run 10\u201320 \u00b0C higher than PET. The shoulder zone for PETG can remain at the same absolute temperature as PET without crystallization risk. Update the product recipe in the PLC.<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/td>\n<\/tr>\n
\n\n\n\n\n
\n
2<\/div>\n<\/td>\n
\n
Pre-Blow Pressure Timing<\/div>\n
PETG is more compliant at blow temperature than PET and requires an earlier pre-blow air trigger relative to stretch rod position. Typical adjustment: 5\u201310 ms advance relative to the PET recipe. Prevents base-thinning caused by material stretching ahead of rod contact.<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/td>\n<\/tr>\n
\n\n\n\n
\n
3<\/div>\n<\/td>\n
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Cooling Dwell Time<\/div>\n
PETG has lower thermal conductivity than PET and requires 10\u201320% longer mold-hold time to reach dimensional stability at ejection. On a machine already running at cycle time limits, this reduces theoretical output by 5\u20138% when switching from PET to PETG.<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Key Decision Summary<\/h2>\n<\/div>\n\n\n\n\n\n\n\n\n\n\n\n\n
Decision Factor<\/th>\nChoose PET<\/th>\nChoose PETG<\/th>\n<\/tr>\n<\/thead>\n
Container geometry<\/td>\nRound, mild oval<\/td>\nIrregular, asymmetric, multi-faceted<\/td>\n<\/tr>\n
Required clarity<\/td>\nHigh (oriented)<\/td>\nVery high (amorphous throughout)<\/td>\n<\/tr>\n
Scratch resistance<\/td>\nBetter<\/span> (H\u20132H hardness)<\/td>\nLower<\/span> (B\u2013HB hardness)<\/td>\n<\/tr>\n
Crystallization risk<\/td>\nPresent<\/span> \u2014 ceiling temp control required<\/td>\nNone<\/span> \u2014 amorphous at all temperatures<\/td>\n<\/tr>\n
Machine platform<\/td>\nES multi-cavity preferred<\/td>\nFS single-cavity for complex shapes<\/td>\n<\/tr>\n
Planar stretch ratio<\/td>\n8\u201312 (optimal)<\/td>\n6\u201310 (do not exceed 11)<\/td>\n<\/tr>\n
Output vs equivalent cavity<\/td>\nHigher<\/span> (shorter cooling dwell)<\/td>\n~5\u20138% lower<\/span> (longer cooling dwell)<\/td>\n<\/tr>\n
Preform availability<\/td>\nWide \u2014 standard PCO sizes<\/td>\nMore limited \u2014 confirm supply first<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

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Frequently Asked Questions<\/h2>\n<\/div>\n

<\/p>\n

\n\u25b6 \u00a0Can PET and PETG be processed on the same mold set?<\/summary>\n
Yes, in most cases. PET and PETG preforms for the same container are typically designed with identical neck finish dimensions and similar body geometry. The mold requires no modification. What changes are the preform wall thickness distribution (PETG preforms for irregular shapes are often designed with thicker walls at stress concentration points) and the machine conditioning parameters. Confirm preform compatibility with your preform supplier before running a material switch trial.<\/div>\n<\/details>\n

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\n\u25b6 \u00a0Why does PETG produce better clarity in irregular shapes than PET?<\/summary>\n
In PET, achieving clarity requires sufficient biaxial orientation across the entire container surface. In an irregular geometry \u2014 particularly in panel zones with low local stretch ratio \u2014 PET can remain partially unoriented, showing as haze or reduced gloss. PETG is amorphous at all strain levels and does not require orientation for transparency. A flat panel on a PETG bottle with a local stretch ratio of 3:1 remains as clear as the body at 9:1. This is the core optical advantage of PETG for premium cosmetic containers with complex surface geometry.<\/div>\n<\/details>\n

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\n\u25b6 \u00a0What is the maximum wall thickness the FS platform can condition correctly for PETG?<\/summary>\n
The FS-1CG series handles preform wall thicknesses up to approximately 6.5 mm in PETG at a conditioning dwell of 18\u201320 seconds. Above this wall thickness, the outer surface of the preform reaches blow temperature before the inner surface reaches Tg \u2014 producing a temperature gradient through the wall that results in uneven biaxial orientation and panel zone thinning. If your PETG container design requires a preform wall above 6.5 mm, discuss preform geometry redesign with the mold engineering team before specifying the machine.<\/div>\n<\/details>\n

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\n\u25b6 \u00a0Does processing PETG void the food-contact compliance of the container?<\/summary>\n
PETG homopolymers and standard copolymers processed without plasticizers or UV stabilizers comply with FDA 21 CFR 177.1315 for food-contact use. EU compliance falls under Regulation (EU) No 10\/2011. For cosmetic packaging \u2014 skin-contact but not food-contact \u2014 the relevant framework is the EU Cosmetics Regulation (EC) No 1223\/2009, which addresses the finished product, not the container directly. Standard food-grade PETG grades are routinely accepted for cosmetic packaging use by brand compliance teams.<\/div>\n<\/details>\n

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Ready to specify your cosmetic bottle line?<\/p>\n

Share your container volume, body diameter, neck finish, and target BPH \u2014 receive a specific model recommendation from the 23-model HGA range within 24 hours.<\/p>\n

View Full Machine Specifications \u2192<\/a><\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

Cosmetic bottle manufacturers choosing between PET and PETG face a decision that goes beyond material cost. The resin choice determines preform geometry, conditioning station temperature profile, allowable stretch ratio, and ultimately which machine platform \u2014 multi-cavity ES or single-cavity FS \u2014 can actually deliver the dimensional tolerances the container design requires. This guide works through […]<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[43],"tags":[45],"class_list":["post-1160","post","type-post","status-publish","format-standard","hentry","category-isbm-machine-blog","tag-petg-blow-molding--cosmetic-bottle-machine--pet-vs-petg-processing"],"_links":{"self":[{"href":"https:\/\/ever-powers.com\/en_ca\/wp-json\/wp\/v2\/posts\/1160","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ever-powers.com\/en_ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ever-powers.com\/en_ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ever-powers.com\/en_ca\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ever-powers.com\/en_ca\/wp-json\/wp\/v2\/comments?post=1160"}],"version-history":[{"count":4,"href":"https:\/\/ever-powers.com\/en_ca\/wp-json\/wp\/v2\/posts\/1160\/revisions"}],"predecessor-version":[{"id":1166,"href":"https:\/\/ever-powers.com\/en_ca\/wp-json\/wp\/v2\/posts\/1160\/revisions\/1166"}],"wp:attachment":[{"href":"https:\/\/ever-powers.com\/en_ca\/wp-json\/wp\/v2\/media?parent=1160"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ever-powers.com\/en_ca\/wp-json\/wp\/v2\/categories?post=1160"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ever-powers.com\/en_ca\/wp-json\/wp\/v2\/tags?post=1160"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}