HDPE for almost every shampoo, conditioner and body wash: opaque, squeezable, shower-safe, softening point 125–135°C, recycling code 2, and it takes a soft-touch matte spray. PET only for a clear gel — glass-like, moderate squeeze, and it swells and hazes above ~30% ethanol, so styling waters and scalp tonics go in glass or alcohol-rated PETG. Use 24/410 on 200–300 ml and 28/410 on 300–1,000 ml (410 = 1.5 thread turns). Every filled bottle passes a vacuum leak test at −0.06 MPa (−0.08 MPa for 15 min, loss ≤0.5% for volatile formulas) and 24 h inverted before it ships.
HDPE vs PET: the properties that decide it
Both resins are commodity plastics and both are made into bottles by every haircare partner factory in Guangdong. They are made differently — HDPE by extrusion blow moulding, PET by injection-stretch blow moulding from a preform — and that difference explains almost everything in the table.
| Property | HDPE | PET | What it means for a shampoo bottle |
|---|---|---|---|
| Process | Extrusion blow-moulded | Injection-stretch blow from a preform | PET neck is formed at the preform stage and does not change during blowing — tighter neck tolerance |
| Appearance | Opaque; natural, white, black or coloured | Clear, glass-like | PET only earns its place if the gel colour is part of the product story |
| Squeeze | Best of the two; wall can be set thin enough to squeeze, thick enough to feel solid (≥0.3 mm) | Moderate; rigid at thicker walls | Wash-off products handled wet want HDPE |
| Density / softening | 0.941–0.960 g/cm³; softens 125–135°C | Avoid hot-fill above ~60°C | Neither is hot-filled for shampoo; HDPE tolerates a hot container in summer with more margin |
| Chemical resistance | Good across surfactant systems | Fails above ~30% ethanol — swells, hazes, deforms | Alcohol-bearing styling water or scalp tonic goes in glass or alcohol-rated PETG, never PET |
| Decoration | Takes sprayed matte and soft-touch; coating must pass a wet-rub test | Screen print, label, shrink sleeve; spray hides the clarity you paid for | HDPE for matte families; PET for clear with a label |
| Recycling | Code 2, mono-material; PCR-HDPE 30–100% available | Code 1; PCR-PET available | Either supports a PPWR-facing claim; PCR base tone runs grey or beige and shifts by lot |
| Indicative MOQ, stock undecorated | From ~500 pcs | From ~500 pcs | Same routes: 2,000 print; 2,000–5,000 sprayed per shape; 5,000–10,000 moulded-in |
The rule that falls out of the table: HDPE unless the customer must see the product. Where a clear body is wanted for a heavier, more premium feel, PETG costs more than PET, is treated as rigid, and has alcohol-rated grades — check each grade against the actual ethanol level. The material-by-formula logic for every other product type is on the formula-to-packaging compatibility matrix.
24/410 vs 28/410: what the numbers mean
A neck finish is written diameter / thread series. The first number is the T dimension — the outer thread diameter in millimetres. The second fixes the thread profile and how many turns the neck carries: 400 is one turn (short neck; glass serum bottles), 410 is 1.5 turns (medium neck; plastic lotion and shampoo bottles), 415 is two turns (tall neck; droppers and sprayers). Haircare uses 410 because the extra engagement suits a heavier disc-top, flip-top or pump on a bottle that is handled wet and dropped in a shower.
| Neck | Bottle sizes on partner-factory stock moulds | Closures that fit | Note |
|---|---|---|---|
| 24/410 | 200–300 ml | Disc-top, flip-top, Ø24 lotion pump (1.0/2.0 cc typical) | The common travel and conditioner size |
| 28/410 | 300–1,000 ml | Disc-top, flip-top, Ø28 lotion pump (2.0 or 3.5 cc typical), large pump on 500 ml+ | The standard shampoo and body-wash neck; 1,000 ml HDPE + large pump is the standard large-format pack |
| 18/410, 20/410 | ≤200 ml | Small treatment pumps, disc-top | Leave-in and travel minis |
| 24/415, 28/415 | Tall-neck sprayers | Fine-mist and trigger sprayers | A 28/410 pump will not seat on a 28/415 neck even though both are 28 mm |
The one rule that prevents most fit problems: specify the neck on the bottle drawing first, then buy the closure to it. If the drawing a supplier sends shows only T and X, ask for E, I, S, A, D and Z before you approve anything — I sets the pump dip-tube and plug size, S controls how far the cap turns before the liner meets the land. The full symbol table and the torque thresholds are on neck finish and closure standards.
Closure numbers to write into the spec
- Screw / disc-top opening torque: 0.2–0.7 N·m; reverse torque ≥2.5 N·m without slipping; application torque 0.6–1.2 N·m for seal testing.
- Flip-top: opening force 0.5–3.5 N·m; hinge 100 cycles at 180° on bottle flip-tops with no fracture. A weak hinge pops open in a bag.
- Lotion pump: Φ24 or Φ28 to match the neck; ≥1,500 actuations; ≥95% of an aqueous fill recovered; single stroke ±15%, 50-stroke average within 5–10% of spec.
- Thread clearance: 0.1–0.8 mm; no thread strip at rated torque.
The liner seals; the thread only supplies compression. Raising torque improves the seal only up to a point — beyond it the cap distorts or the liner is crushed and the seal fails by itself. A narrower sealing land seals better at the same torque.
The leak test a filled bottle must pass
This is identical for HDPE and PET, and it is done on filled, capped bottles — not empties — because the closure, the liner and the formula are all part of the seal.
| Test | Method | Pass threshold |
|---|---|---|
| Vacuum leak (quick check) | Filled, capped, lying and inverted on white absorbent paper in a vacuum chamber | −0.05 MPa for 5 min, no trace on the paper — what a line operator runs |
| Vacuum leak (report) | Same, full test | −0.06 MPa for standard shampoo and conditioner; −0.08 MPa for 15 min, loss ≤0.5% for volatile or alcohol-bearing formulas |
| Static seal | Filled, capped at 0.6–1.2 N·m, inverted | 24 h, no leakage |
| Thermal | Oven and freezer, filled | 48°C and −15°C, 24–48 h each; closures −24°C / +50°C; no crack, leak or colour loss |
| Drop | Filled bottle with closure onto concrete | 1.5 m at 45°, no functional damage |
| Coating (sprayed HDPE) | 3M 810 over 2 mm cross-hatch pulled at 45°; wet-rub | No lift; pencil hardness ≥2H; no marking in the shower |
| Wall | Calliper and balance | Blow-moulded wall ≥0.3 mm; fit-critical dimensions ≤0.5 mm, overall ≤1.0 mm |
| Heavy metals | Third-party laboratory | Pb + Cd + Hg + Cr(VI) ≤100 ppm |
Acceptance is arithmetic: ISO 2859-1 general level II, AQL 0 critical / 1.0–1.5 major / 2.5–4.0 minor, with colour judged against a signed golden sample at ΔE under D65 — shampoo and conditioner side by side in one hand. The gates these tests sit under are described on cosmetic packaging quality standards.
Decision in four lines
- Does the customer need to see the product? No → HDPE. Yes → PET (or PETG for a heavier feel).
- Any ethanol above ~30%? Yes → glass or alcohol-rated PETG, whatever the answer to line 1.
- Size 200–300 ml → 24/410; 300–1,000 ml → 28/410. Put the neck on the bottle drawing before you look at closures.
- Write the −0.06 MPa vacuum test, the 24 h inversion and the wet-rub into the purchase order. If the report does not show them, the bottle was not tested.
The formats are on HDPE shampoo bottles, the range on haircare and bodycare packaging, and the minimums on the MOQ index 2026. Vella is a Guangzhou-based beauty packaging solutions provider — a sourcing partner, not a factory — that routes briefs like this one to vetted partner factories operating to ISO 22716 / GMP, matches the components as one set, and runs the tests above on filled samples before any production run. Supplier questions that separate a tested bottle from a quoted one are in how to evaluate a China packaging supplier; send your brief via the contact page.
Common questions
- Sunscreen Bottle Options: Tube, Airless, Pump Bottle and Stick — Sizes, SPF Compatibility and MOQ
- Toner Bottles: Glass vs PET, 100–200 ml Sizes, Flip-Top, Disc-Top and Spray Closures, MOQ
- Body Butter Containers: 100–500 ml Jars in PP, PET and Glass, Wide-Mouth Closures, MOQ and Lead Time
- Airless vs Tube for Sunscreen: Dose, UV Protection, Cost and MOQ
- Acrylic vs Glass vs PP Cream Jar: Which Is Right for a Moisturiser, and Why PMMA Needs a Liner
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