400, 410, 415 — what the second number means.
Neck finishes are written diameter / series. The diameter is the T dimension (outer thread diameter) in millimetres. The series fixes the thread profile, pitch and how many turns of thread the neck carries — which is why an 18/400 cap will not seat properly on an 18/415 neck even though both are 18 mm.
| Series | Thread turns | Neck height | Typical use in cosmetics |
|---|---|---|---|
| 400 | 1 turn | Short | Glass serum and toner bottles (18/400, 20/400, 22/400); fast capping on high-speed lines; most dropper assemblies |
| 410 | 1.5 turns | Medium | Plastic and acrylic lotion bottles with pumps (18/410, 20/410, 24/410, 28/410); more thread engagement for heavier closures |
| 415 | 2 turns | Tall | Tall-neck droppers and sprayers (15/415, 18/415, 28/415); perfume and essential-oil bottles where a long, secure engagement is wanted |
| Format | Common finishes | Notes |
|---|---|---|
| Glass narrow-neck (serum, toner, oil) | 18/400, 20/400, 22/400 | Dropper pipettes, orifice reducers, small treatment pumps |
| Plastic / acrylic bottle (lotion, cream, toner) | 18/410, 18/415, 20/410, 20/415, 24/410, 28/410, 28/415 | Lotion pumps Ø18-Ø38 are matched to the same T dimension |
| PET blow-moulded bottle | Ø18, Ø20, Ø22, Ø24, Ø28, Ø33 in 400 / 410 / 415 | Neck is formed at the preform stage and does not change during blowing |
| Wide-mouth jar | Ø33, Ø38, Ø43, Ø48, Ø63, Ø70, Ø83, Ø89, Ø100 | Metallised aluminium or plastic caps, disc liner; solid balms and creams |
| Tubular (drawn) glass vial | Ø10, Ø15, Ø20, Ø25, Ø30 | Ampoules, sample vials, roll-on 5-10 ml |
| Perfume / fine fragrance | FEA 15 crimp; 15/415, 18/415 screw | FEA 15 takes crimp-on pumps (permanent); 415 finishes take screw-on sprayers |
| Mist spray | 12.5-24 mm pump sizes, 0.1-0.2 ml per shot | Pump size is chosen to the bottle neck, never the reverse |
One rule saves most fit problems: specify the neck finish on the bottle drawing first, then buy the closure to it. Where a set spans glass and plastic (a glass bottle with a plastic cap, say) the closure factory needs the glass neck drawing, because glass neck tolerances are wider than injection-moulded ones.
Reading a neck-finish drawing: Z, A, T, E, I, S, D, X.
Bottle and closure drawings use a fixed set of letters. If a supplier's drawing shows only T and X, ask for the rest before you approve tooling.
| Symbol | Dimension | Why it matters |
|---|---|---|
| T | Outer thread diameter | The headline number in 18/400; closure thread is cut to it |
| E | Outer neck diameter (thread root) | Clearance between cap skirt and neck; too tight and the cap binds |
| I | Inner bore diameter | Sets the plug, orifice reducer, dropper pipette and pump dip-tube size |
| S | Top of finish to start of thread | Controls how far the cap turns before the liner meets the land |
| X | Total neck height | Must match cap skirt height; a 415 neck is taller than a 400 |
| A | Lock-ring (tamper band) diameter | Tamper-evident bands and snap-on overcaps engage here |
| D | Lock-ring height | Position of the tamper band relative to the land |
| Z | Support-ring diameter | Where the capping machine chuck and conveyor rails hold the bottle |
How a cap seals, and why a narrower land seals better.
Closures are classed three ways: by material (all-plastic; aluminium-over-plastic; anodised or metallised aluminium), by opening action (disc-top, flip-top, screw, snap, orifice/plug, flow-control) and by application (tube caps, lotion-bottle caps, household caps). A flip-top is a lower cap, orifice, hinge, upper cap, plug pin and inner plug; hinges are one-piece, butterfly or three-axis strap type. Every one of them seals the same way.
The liner seals; the thread only supplies compression. The liner must be elastic enough to fill every unevenness of the bottle land, yet stiff enough to keep pressing back. Raising torque improves the seal only up to a point — beyond it the cap cracks or distorts, a glass neck chips, or the liner is crushed and the seal fails by itself. Because the closing force is spread over the sealing surface, a wider land gives a worse seal at the same torque. The design consequence: keep the sealing surface as narrow as the liner can tolerate, and where application torque is limited (light caps, hand capping, small necks) choose a narrow sealing ring to reach the highest effective sealing pressure.
Three things a buyer checks before approving a closure: opening torque (too high and the customer cannot open it, too low and it leaks), neck tolerance match between the bottle and the cap drawings, and the orientation lug — when cap and bottle carry a continuous design, the lug on the neck, not the artwork, is the reference for alignment.
The thresholds closures are checked against.
| Test | Method | Typical pass threshold |
|---|---|---|
| Opening torque, screw cap | Torque meter after application | 0.2-0.7 N·m; further tightening does not strip the thread |
| Opening force, hinged / flip-top / disc-top | Torque or force gauge | 0.5-3.5 N·m |
| Reverse torque | Over-tighten on bottle | ≥2.5 N·m without slipping |
| Seal, quick method | Cap applied at 0.6-1.2 N·m; vacuum desiccator | -0.05 to -0.06 MPa for 3 min, no water ingress |
| Seal, static | Filled, capped, inverted | 24 h inverted, no leakage |
| Hinge life (flip-top) | Open/close cycling | 200 cycles on tube caps; 100 cycles at 180° on bottle flip-tops; no fracture, no change in snap |
| Coating hardness | Pencil hardness, GB/T 6739 | ≥2H on sprayed outer surfaces; ≥F on hot-stamp, silk-screen and pad-print |
| Coating adhesion | Cross-hatch, GB/T 9286 | Grade 1 or better; decoration: (10±1) N/25 mm tape, 90° fast pull, no lift |
| Thermal | Oven and freezer, filled | -24°C and +50°C: no cracking, deformation, leakage, coating crack or colour loss |
| Decoration position | Top artwork vs cap OD centre | Offset ≤0.6 mm; decoration joint mis-step ≤0.3 mm, overlap ≤1.5 mm with no gap |
| Cleanliness | 75% alcohol flushed 12 times, light box | No particle >0.5 mm, no fibre >2 mm |
| Storage | Warehouse | Dry and ventilated, ≤12 months; if stored below 15°C, condition above 15°C for 24 h before use |
These numbers sit inside the wider battery on our QC standards page — vacuum leak, 3M tape adhesion, drop, pump life — and partner factories operate to ISO 22716 / GMP. On pumps the matching figures are ≥1,500 actuations, priming ≤5 strokes for aqueous and ≤10 for non-aqueous bulks, and output ≥95% / ≥90% respectively.
Orifice reducers: small hole for water, large hole for lotion.
Solid or balm-type products go in a wide-mouth jar with an aluminium or plastic cap and a disc liner. Emulsions and water-phase products go in narrow-neck bottles with a pump — or, if a plain cap is used, with an inner plug. Water-thin formulas take a small-orifice plug so the product does not gush; thicker emulsions take a large-orifice plug so the product actually dispenses. Plugs are PP or PE; when a set includes a pump for one SKU and a plug-cap for another, both must be cut to the same I (bore) dimension, which is why we insist on the full neck drawing.
Frequently asked
Send us the spec, we will source against it.
Tell us the format, the neck finish if you know it, and the quantity. Your quote comes with the bottle and closure drawings cross-checked so the set fits before tooling is cut.
Related reading.
- QC standards with the numbers — the full test battery these torque and seal thresholds belong to.
- Glass bottle specifications — glass grades, forming methods, 18/400-22/400 necks, MOQ and mould costs.
- Cosmetic tube specifications — tube caps, print-area table Ø13-Ø60 and seal-strength thresholds.
- Dropper bottles — 18/400, 20/400 and 18/415 pipette assemblies.
- Perfume bottles — FEA 15 crimp necks and 15/415 screw sprayers.
- Real minimum order quantities, by route — what stock-mould and private-mould closures actually cost to start.