PET Glitter Wholesale Sizes: Hexagon & Diamond Cut Technical Specification Guide for Cosmetic Formulators

The Problem Statement Nobody Wants to Talk About

Let me be direct. If you have ever opened a pilot batch of nail lacquer after a 48-hour oven stability test and found the clear base turned into a murky pink soup, you already know why this article exists. That failure cost one of our customers in São Paulo a three-week reformulation delay and roughly $14,000 in wasted raw materials. The root cause was not the lacquer base. It was a PET glitter with an inadequately cross-linked coating that allowed Solvent Red 49 to migrate into a butyl acetate vehicle within hours.

This document is written engineer-to-engineer, chemist-to-chemist. We are not going to talk about how glitter "adds sparkle to your brand vision." We are going to talk about BOPET crystallinity percentages, rotary slitting burr tolerances, electrostatic clumping in powder hoppers, and why your 0.4mm diamond-cut particles keep settling out of your carbomer gel.

At MLM Cosmetic (mlmcosmetic.com), our Shenzhen facility produces Solvent Resistant Standard Glitter and specialty effect particulates as OEM raw materials. We supply batch-specific CoA documentation including ICP-MS heavy metal panels and FTIR coating verification. What we do not do is make finished product safety claims—that responsibility sits with your brand's qualified safety assessor, as it should.

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Chemical & Substrate Architecture: What Is Actually Inside the Flake

BOPET Film Fundamentals

The carrier substrate for cosmetic-grade PET glitter is biaxially oriented polyethylene terephthalate (BOPET) film, typically 12µm to 25µm gauge. The biaxial orientation process—sequential stretching in machine direction then transverse direction at temperatures between 85°C and 110°C—produces a semi-crystalline film with crystallinity in the 35–45% range (measured via DSC at 10°C/min ramp rate). This crystallinity window matters because it directly governs two things you care about:

1. Solvent barrier performance. Higher crystallinity reduces free volume in the polymer matrix, slowing diffusion of small-molecule solvents like ethyl acetate (MW 88.1) and butyl acetate (MW 116.2). Below 30% crystallinity, solvent ingress rates climb sharply.
2. Brittleness and slitting behavior. Push crystallinity above 50% and the film becomes glassy. Rotary die-cutting produces micro-fractures and edge burrs that shed sub-50µm fragments—fragments that will absolutely show up as haze in a clear gel base and may raise microplastic compliance questions under EU 2023/2055.

Our standard BOPET film runs at 40 ± 3% crystallinity. We verify each incoming film lot by DSC (TA Instruments Q2000) before it enters the metallizing or coating line.

Coating Stack Architecture

A cosmetic PET glitter flake is not just metalized film. The typical cross-section from bottom to top:

1. BOPET carrier film (12–23µm)
2. Vacuum-deposited aluminum layer (40–80nm optical density 2.0–2.8) or high-refractive-index metal oxide for color-shift effects
3. Colorant layer — organic dyes (CI 77491, Solvent Red 49, etc.) or inorganic pigments dispersed in a binder resin
4. Protective topcoat — this is where solvent resistance lives or dies

For standard aqueous/oil-phase applications (body lotions, water-based gels), a single-cure polyurethane topcoat at 2–3µm DFT is adequate. For nail lacquer and any formulation containing ketones, esters, or aromatic solvents, we apply a dual-cure silane-modified acrylic/epoxy topcoat. The silane cross-linking produces a Si–O–Si network with markedly higher solvent resistance. We verify cure completion by FTIR: the disappearance of the epoxide ring absorption at 915 cm⁻¹ and the Si–O–Si stretch confirmation at 1020–1090 cm⁻¹.

If your current supplier cannot produce an FTIR spectrum of their cured topcoat on request, that is a red flag worth investigating.

Rotary Die Cutting: Hexagon vs. Diamond Geometry

Both hexagon and diamond (rhombic) cuts are produced on rotary die-cutting lines. The distinction matters beyond aesthetics:

Hexagonal cuts (regular hexagon, interior angles 120°) produce particles with a uniform edge-to-face ratio. This geometry packs efficiently in a 2D plane—think honeycomb tessellation—which translates to higher surface coverage per gram in pressed powder applications. Hexagons also exhibit more predictable hydrodynamic drag in suspension because the particle presents a similar cross-section regardless of orientation.

Diamond cuts (rhombic, typically 60°/120° acute/obtuse angles) produce a more elongated particle with a higher aspect ratio. The visual effect is a directional flash—more linear light return, less uniform shimmer. The trade-off: diamond particles are more prone to alignment during flow, which can create streaking in roller-applied or spray formulations. The acute 60° corners are also mechanically weaker; we see higher corner chip rates during pneumatic conveying if the air velocity exceeds 15 m/s.

Slitting knife condition is critical for both geometries. We replace rotary die blades every 800,000 linear meters and inspect edge burr height under 200× magnification. Target burr height is < 5µm. Burrs above 10µm create hook-like projections that interlock between particles, causing clumping in the bag and poor dispersion in your mixer.

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Temperature & Solvent Resistance: Real Engineering Data

Thermal Performance Envelope

Condition	Standard PET Hex	Solvent-Resistant PET Diamond	Regenerated Cellulose
Continuous service temp	160°C (320°F)	180°C (356°F)	90°C (194°F)
Peak short-duration (< 30 min)	200°C (392°F)	220°C (428°F)	110°C (230°F)
Onset of visible curl/warp	210°C	235°C	105°C
DSC glass transition (Tg) of topcoat	78°C	112°C	62°C

Practical implication: if you are pouring anhydrous lip balm sticks at 82–88°C, standard PET hex is fine. If you are running a hot-pour wax depilatory at 95°C with a 20-minute hold time, standard PET still works but cellulose-based bio-glitter will start warping. For high-temperature sintered pressed powders (some Korean-method baking processes reach 150–165°C), you need the solvent-resistant grade or you will see topcoat delamination.

Solvent Immersion Test Results (MLM Internal Protocol QC-SR-07)

Test method: 1.0g glitter immersed in 50mL solvent in sealed borosilicate vial, held at 45°C ± 2°C for 72 hours. Visual inspection at 24h, 48h, 72h. Solvent clarity measured by ASTM D1003 haze meter (BYK haze-gard i) against neat solvent blank.

Solvent System	Std PET Hex (Haze Δ)	SR PET Diamond (Haze Δ)	Cellulose (Haze Δ)
Ethyl acetate	+18.4% ⚠️ FAIL	+1.2% ✅ PASS	+31.7% ⚠️ FAIL
Butyl acetate	+14.1% ⚠️ FAIL	+0.8% ✅ PASS	+28.3% ⚠️ FAIL
Isopropanol	+2.3% ✅ PASS	+0.4% ✅ PASS	+4.1% ✅ PASS
MEK (methyl ethyl ketone)	+22.6% ⚠️ FAIL	+2.9% ✅ PASS	N/T (substrate dissolves)
Water/glycerin 70:30	+0.1% ✅ PASS	+0.1% ✅ PASS	+0.3% ✅ PASS
Dimethicone (5 cSt)	+0.2% ✅ PASS	+0.1% ✅ PASS	+0.5% ✅ PASS

Pass threshold: Haze increase < 5.0% vs. neat solvent. The data is unambiguous: if your formulation contains ethyl acetate or butyl acetate—and virtually every nitrocellulose nail lacquer does—standard PET glitter will bleed. Full stop. Specify solvent-resistant grade or reformulate your vehicle.

A note on Brookfield viscosity impact: adding 2% w/w of 0.4mm hex PET glitter to a carbomer 940 gel (initial viscosity 45,000 cP at 20 RPM, spindle #6, Brookfield RVT) increased apparent viscosity by roughly 8–12% due to particle-particle interaction. At 5% loading, the increase was 22–28%. If you are targeting a specific viscosity window for filling, account for this and adjust your carbomer neutralization or polymer loading accordingly. Do not blame the glitter when your filling line backs up because the viscosity shifted 15,000 cP.

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Formulation Compatibility Matrix

Application	Recommended Cut	Size Range	Grade	Key Risk	Mitigation
Nail lacquer (nitrocellulose)	Diamond 0.4mm	0.2–0.8mm	Solvent-Resistant	Dye migration into BA/EA vehicle	Verify SR topcoat FTIR; 72h immersion test
Lip gloss (polybutene base)	Hexagon 0.2mm	0.05–0.4mm	Standard PET	Settling in low-viscosity base	Yield stress ≥ 1.8 Pa via fumed silica or organoclay
Pressed eyeshadow	Hexagon 0.1mm	0.05–0.2mm	Standard PET	Electrostatic clumping in hopper	Ground hopper, ionizing bar, 40–55% RH
Body gel (carbomer)	Hexagon 0.4mm	0.2–1.0mm	Standard PET	Viscosity shift at >3% loading	Pre-calibrate Brookfield at target loading
Hot-pour lip balm (85°C)	Hexagon 0.2mm	0.1–0.4mm	Standard PET	Thermal curl if hold time >45 min	Keep melt temp ≤ 90°C, pour within 30 min
Wax depilatory (95°C)	Hexagon 0.4mm	0.2–0.8mm	Solvent-Resistant	Topcoat softening near Tg	Use SR grade (Tg 112°C)
UV gel nail (acrylate cure)	Diamond 0.2mm	0.1–0.4mm	Solvent-Resistant	Oxygen inhibition layer trapping particles	Ensure full cure; wipe inhibition layer post-cure
Bath bomb (effervescent)	Hexagon 1.0mm	0.4–3.0mm	Cellulose Bio-Glitter	EU microplastic compliance	Cellulose substrate exempt under EU 2023/2055

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Quality Control & Batch Auditing

ICP-MS Heavy Metal Panel

Every production batch is tested on our Agilent 7800 ICP-MS (single-quad, helium collision mode for polyatomic interference removal). Our release limits:

• Lead (Pb): < 2.0 ppm (reporting limit 0.1 ppm)
• Arsenic (As): < 1.0 ppm (reporting limit 0.05 ppm)
• Mercury (Hg): < 1.0 ppm (reporting limit 0.02 ppm)
• Cadmium (Cd): < 1.0 ppm (reporting limit 0.05 ppm)
• Antimony (Sb): < 5.0 ppm (reporting limit 0.1 ppm)

Antimony deserves specific attention. Sb₂O₃ is used as a polycondensation catalyst in PET resin manufacturing. Residual Sb in the BOPET film typically runs 150–250 ppm in the bulk polymer, but extractable Sb under simulated cosmetic use conditions (sweat simulant, 40°C, 24h) is well below 5 ppm. We report extractable Sb, not total Sb, because that is what matters toxicologically. If your supplier reports total Sb at 200 ppm without specifying the extraction protocol, ask them to clarify. The numbers are not comparable.

FTIR Coating Verification

We run ATR-FTIR (Thermo Fisher Nicolet iS50, diamond ATR crystal, 4 cm⁻¹ resolution, 32 scans) on every batch of solvent-resistant grade to confirm:

1. Epoxide ring consumption at 915 cm⁻¹ (must be absent or < 5% residual peak area vs. uncured reference)
2. Si–O–Si network formation at 1020–1090 cm⁻¹
3. Absence of free isocyanate at 2270 cm⁻¹ (relevant for PU-coated standard grades—residual NCO means incomplete cure and potential skin sensitization risk)

FTIR spectra are included in the CoA package upon request. We strongly recommend that your incoming QC lab overlay our spectrum against their own ATR measurement of the received material as a fingerprint identity check.

Particle Size Distribution Verification

We use laser diffraction (Malvern Mastersizer 3000, dry dispersion) for sub-200µm particles and optical image analysis (Microtrac CAMSIZER X2) for particles above 200µm. The CAMSIZER simultaneously reports aspect ratio, circularity, and corner integrity—this is how we catch die wear before burr height becomes a problem.

Typical PSD spec for a 0.4mm (1/64") hexagon cut: D10 = 350µm, D50 = 400µm, D90 = 440µm. If the D90/D10 span exceeds 0.30, we flag the batch for die inspection.

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Benchtop Qualification Protocol: Three Tests Before You Commit to a Production Run

Before you order 25kg drums and commit to a production schedule, run these three tests on a 1kg trial sample. Each test takes less than a day of bench time and will save you from the kind of $14,000 disaster I mentioned at the top.

Test 1: Solvent Immersion (Dye Migration Screen)

What you need: 50mL borosilicate vials with PTFE-lined caps, your actual formulation vehicle (not a proxy solvent—use your real nail lacquer base, your real gel matrix), analytical balance, haze meter or at minimum a visual lightbox.

Procedure:

1. Weigh 1.00g glitter into vial.
2. Add 50mL of your vehicle solvent or base.
3. Cap tightly. Place in oven at 45°C ± 2°C.
4. Inspect at 24h, 48h, 72h.
5. At 72h, filter through 0.45µm PTFE syringe filter. Measure filtrate haze (ASTM D1003) or absorbance at 400–700nm on a UV-Vis spec.

Pass criteria: Haze increase < 5% vs. neat vehicle. No visible color in filtrate. If you see color at 24h, stop the test—that glitter grade is incompatible with your vehicle.

Test 2: Thermal Stability (Hot-Pour Simulation)

What you need: Aluminum weighing dishes, lab oven, stereomicroscope (40×).

Procedure:

1. Spread a monolayer of glitter particles on an aluminum dish.
2. Place in oven at your actual pour/process temperature for your actual hold time (e.g., 88°C for 30 minutes for lip balm).
3. Remove, cool to ambient, examine under stereomicroscope at 40×.

Pass criteria: No visible curling, delamination, or color shift. Compare against an unheated control sample side-by-side. Photograph both for your batch record.

Test 3: Suspension Stability (Accelerated Settling)

What you need: 100mL graduated cylinder, your finished (or near-finished) formulation with glitter dispersed at target loading, centrifuge (optional for acceleration).

Procedure:

1. Fill graduated cylinder to 100mL mark with glitter-loaded formulation.
2. Allow to stand undisturbed at 25°C for 72h (or centrifuge at 3000 RPM for 30 min as accelerated proxy).
3. Measure clear supernatant layer height as percentage of total.

Pass criteria: < 5% clear separation at 72h ambient. If you see >10% separation, your continuous phase yield stress is too low for the particle size and density you are using. Increase your rheology modifier concentration or drop to a smaller particle size. A 0.2mm hex at SG ~1.4 is far easier to suspend than a 1.0mm hex at the same density—the Stokes settling velocity scales with the square of the particle diameter.

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Regulatory Landscape: What You Actually Need to Know

EU: Regulation 1223/2009 and Annex XVII Entry 51 (Microplastics)

The EU microplastic restriction under REACH (Commission Regulation (EU) 2023/2055, Annex XVII) restricts synthetic polymer microparticles < 5mm intentionally added to products. Cosmetic glitter made from PET falls squarely within scope. The transition periods are staggered:

• Rinse-off cosmetics: Restricted from October 2027
• Leave-on cosmetics: Restricted from October 2029 (with potential extension mechanisms for specific applications)

This is not a future hypothetical. If you are developing products for EU market launch in 2026–2027, your formulation timeline needs to account for the rinse-off deadline now. For rinse-off applications targeting EU, consider regenerated cellulose bio-glitter or synthetic fluorphlogopite (synthetic mica) substrates, which are exempt as they are not synthetic organic polymers.

For leave-on applications, PET glitter remains usable until October 2029 under current timelines. But reformulation lead times in color cosmetics are typically 12–18 months. Plan accordingly.

US: FDA MoCRA

The Modernization of Cosmetics Regulation Act (MoCRA), signed December 2022, requires facility registration and product listing with FDA. It also mandates adverse event reporting and grants FDA mandatory recall authority. MoCRA does not currently restrict PET glitter as a material category, but it does require that brands maintain adequate safety substantiation for every ingredient.

MLM Cosmetic's Shenzhen facility is registered under FDA MoCRA requirements. We provide batch-specific Certificates of Analysis (CoA) including ICP-MS heavy metal panels, FTIR coating identity, and particle size distribution data. These documents are designed to support your brand's safety substantiation files. To be unambiguous: MLM Cosmetic supplies cosmetic raw materials and provides batch test documentation (CoA, ICP-MS, FTIR) upon request to support brand filings. Finished formulation safety assessment and regulatory compliance remain the responsibility of the brand owner and their qualified safety assessor (EU CPSR) or responsible person.

China: NMPA

For brands selling into China, glitter used in cosmetic products must comply with the NMPA's Cosmetic Safety Technical Specifications (2015 edition, updated). Heavy metal limits under NMPA are broadly aligned with EU/US thresholds. We can provide Chinese-language CoA documentation formatted for NMPA filing support upon request.

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Electrostatic Handling: The Problem Nobody Writes About

PET film is an excellent electrical insulator. Surface resistivity of BOPET is typically 10¹⁴ to 10¹⁶ Ω/sq. When you cut it into thousands of sub-millimeter particles and try to feed them through a stainless steel powder hopper into a ribbon blender, the triboelectric charging is severe. Particles cling to hopper walls, bridge across orifices, and form clumps that disperse unevenly into your batch.

Practical countermeasures we recommend to our customers:

1. Control ambient humidity. Keep your blending room at 45–55% RH. Below 35% RH, triboelectric charging intensity roughly doubles.
2. Install ionizing bars (Simco-Ion or equivalent) at the hopper discharge point.
3. Ground all metal surfaces in the powder handling path—hopper, chute, blender shell. Verify ground continuity quarterly.
4. Avoid pneumatic conveying velocities above 15 m/s for diamond cuts. The acute corners chip and generate fines that exacerbate static issues.
5. Pre-blend with a carrier powder. For pressed eyeshadow, pre-blending glitter with a portion of your talc or sericite at 1:3 ratio before adding to the main batch can dramatically reduce clumping.

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Sourcing & Packaging Specifications

Trial Quantities (R&D / Pilot)

• MOQ: 1 kg per SKU (standard PET hex and SR PET diamond); 5 kg per SKU (cellulose bio-glitter)
• Packaging: Vacuum-sealed aluminum foil barrier bags, MVTR < 0.5 g/m²/day per ASTM F1249. Heat-sealed with tamper-evident closure. Each bag carries a batch-traceable label with lot number, manufacturing date, particle size, and color code.
• Why vacuum-sealed aluminum? Moisture ingress causes hydrolysis of polyurethane topcoats over extended storage. We have seen PU-coated glitter stored in simple PE bags in a Guangzhou warehouse (85% RH, 32°C ambient) develop coating haze within 90 days. The aluminum barrier bag extends shelf stability to 24 months from date of manufacture when stored below 30°C and 60% RH.

Bulk Production Quantities

• Standard pack: 25 kg net in UN-rated fibre drums with PE liner bag. Drum dimensions: 400mm diameter × 580mm height. Palletized 4 drums per layer, 2 layers, 8 drums per pallet.
• Custom packaging available for automated dosing systems (10kg boxes with liner, 500g sachets for contract fillers running small batches).

Lead Times (from Shenzhen)

• Stock colors/sizes: 3–5 business days to ship
• Custom colors (Pantone match): 10–14 business days including lab match, approval sample, and production
• Custom sizes or shapes: 12–21 business days (requires die tooling verification)

All shipments include CoA packet. ICP-MS and FTIR data are generated per-batch, not per-SKU—if you order the same SKU across two production batches, you receive two distinct CoA documents.

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Technical Sourcing Summary

The decision tree for specifying PET glitter in a cosmetic formulation is not complicated, but it requires honest answers to three questions:

1. Does your formulation contain ester solvents, ketones, or aromatic solvents? If yes → solvent-resistant grade, no exceptions. Run Test 1 above on your actual vehicle.
2. Will your product be sold in the EU as a rinse-off product after October 2027? If yes → PET is not viable. Specify cellulose or synthetic mica substrate.
3. Does your process involve temperatures above 100°C for more than 10 minutes? If yes → verify thermal grade. Standard PET is fine to 160°C continuous. Cellulose tops out around 90°C in practice.

Get a 1kg trial bag. Run the three benchtop tests. Review the CoA. Then scale to 25kg drums with confidence that the material will perform in your production environment the same way it performed on your bench.

For technical questions, sample requests, or CoA documentation, contact the MLM Cosmetic technical team through mlmcosmetic.com. We answer formulation compatibility questions directly—no sales pitch required.

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MLM Cosmetic is an OEM cosmetic raw material manufacturer based in Shenzhen, China. We supply effect pigments, glitter, and specialty particulates to cosmetic brand owners and contract manufacturers worldwide. Facility registered under US FDA MoCRA. All technical data presented reflects MLM internal testing protocols and is provided to support customer formulation development. Finished product safety and regulatory compliance are the responsibility of the brand owner.

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Regulatory & Safety Notice

Disclaimer: Technical data and regulatory references provided herein (including EU Regulation 2023/2055, EU Regulation 1223/2009, and US FDA MoCRA) are based on current legislative texts and laboratory test parameters for raw materials manufactured by MLM Cosmetic. This documentation is intended solely to support independent brand formulators and Responsible Persons in compiling their Cosmetic Product Safety Reports (CPSR) and product filings. Final formulation compliance, toxicological risk assessment, and finished product registration remain the responsibility of the brand owner.

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Looking for custom formulation or laboratory testing samples? Contact our MLM Cosmetic technical engineering team or request a free sample kit directly.