Direct Answer
Sachet and stick pack filling turns a formula into a fixed single dose, and the buyer's job is to confirm the format holds that dose without leaking, reacting, or varying. The decisions are format selection — a flat sachet or a narrow stick pack depending on viscosity and retail intent — then film-formula compatibility, seal integrity under pressure, dose accuracy, and tear-open function. A sachet that leaks under transit pressure or varies beyond tolerance defeats the format's purpose. Single-dose suits samples, travel sets, trial sizes, masks, and portion-controlled treatments, where a fixed dose is the point and protecting the formula from repeated opening matters. The buyer should require seal and dose data before volume, because a defective seal in a single-dose format is a product failure the customer experiences in one opening.
Opening Hook
A brand ordered 200,000 serum sachets for a launch campaign, chose a glossy film that looked premium, and signed off from a photograph. The sachets shipped, and the first complaints arrived from airline amenity kits: seals opened in transit, doses varied visibly, and a few leaked into the box. The buyer had specified the look and the count but never the seal integrity, the dose tolerance, or the film-formula compatibility. The single-dose format failed on every property that made it single-dose. At ubitglow, sachet and stick pack filling is specified against seal, dose, and compatibility data, so the format ships with the tests it needs to survive the journey.
Sachet Versus Stick Pack: Choosing the Format
The format decision is driven by viscosity and retail intent, not by a catalogue image.
| Factor | Sachet | Stick Pack |
|---|---|---|
| Viscosity range | Broader, holds creams | Lower, flowable products |
| Retail footprint | Flat, wider | Slim, narrow |
| Tear-open | Tear notch or cut | Tear notch, squeeze |
| Dose size | Larger single dose | Smaller, controlled |
| Typical use | Masks, samples, creams | Serums, travel, trials |
Data: Cosmetic manufacturing-practice standards require that packaging protect the product through its intended use and shelf life, which for a single-dose format means the seal and the film must hold from filling to opening.
Judgment: Select the format from the formula's viscosity and the intended use, because a format chosen for appearance is an untested assumption about how the product will behave inside the pack.
Source: ISO — ISO 22716 Cosmetics Good Manufacturing Practices (2024)
The liquid filling production guide covers how a filling line runs a batch, which is the process that single-dose formats slot into.
Film Compatibility and the Barrier the Product Needs
The film is a material choice, and the wrong film reacts with the formula or lets the wrong things through.
| Film Property | Why It Matters | Failure Signal |
|---|---|---|
| Barrier | Protects actives from air, moisture | Actives degrade |
| Compatibility | No reaction with formula | Film delaminates, odour |
| Seal strength | Holds under pressure | Leak in transit |
| Tear-open | Clean, predictable open | Ragged or hard tear |
| Print adhesion | Label stays on film | Print rubs off |
Seal Integrity and Dose Accuracy: The Two Numbers
Single-dose packaging is proven by two measurements, and both must be specified.
| Measurement | What It Confirms | Test |
|---|---|---|
| Seal integrity | No leak under pressure | Pressure or vacuum test |
| Dose accuracy | Consistent fill per unit | Weight check per dose |
| Tear function | Clean opening | Openability test |
| Residual | Little product left after squeeze | Squeeze-out test |
Data: Ingredient safety assessments document the sensitivity of actives to air, light, and moisture, which is the reason a single-dose film must provide the barrier that the specific formula requires.
Judgment: Match the film barrier to the most sensitive active, because a film that protects the bulk but lets oxygen reach the active has failed the formula even if the seal holds.
Source: Cosmetic Ingredient Review (CIR) — CIR Ingredient Safety Assessments (2024)
The filling and packaging compatibility guide covers how formula and pack are tested together before a format is committed, and the packaging material selection guide maps film options to formula chemistry.
Where Single-Dose Formats Earn Their Cost
Single-dose adds per-unit cost, and it earns that cost only where the format is the point.
| Use Case | Why Single-Dose Works | Buyer Note |
|---|---|---|
| Samples and trials | Low-risk trial | High volume, low dose |
| Travel and amenity kits | Portability | Seal is critical |
| Masks | Fixed application | Dose per mask |
| Portion treatment | Controlled usage | Dose accuracy |
| Premium trial sets | Perceived value | Look plus function |
A Single-Dose Specification Checklist
Six fields turn a sachet or stick pack order into a specification instead of a count.
| Field | What to Specify | Red Flag |
|---|---|---|
| Format | Sachet or stick pack | "Whatever is cheaper" |
| Film and barrier | Named material | No material spec |
| Dose and tolerance | Fill weight range | No tolerance |
| Seal test | Pressure or vacuum method | No seal test |
| Tear-open | Notch and function | No openability check |
| Compatibility | Film-formula data | No compatibility test |
Data: Published test-method standards define how package seal strength and integrity are measured, giving a buyer an objective, repeatable way to specify and verify a single-dose pack.
Judgment: Name the test method in the specification, because a seal claim without a method is an assertion, and a method without a pass limit cannot be audited.
Source: ASTM International — ASTM Standards and Test Methods (2024)
The MOQ and pricing guide covers how single-dose volumes and unit costs are negotiated, since the format's economics differ from a jar or a bottle.
The Cost Structure of Single-Dose Filling
Single-dose is a per-unit cost decision, and the buyer should understand where the cost sits before negotiating volume.
| Cost Component | What Drives It | Buyer Lever |
|---|---|---|
| Film stock | Material and barrier grade | Specify, do not over-specify |
| Dose size | Fill per unit | Right-size the dose |
| Changeover | Format switches on the line | Batch larger runs |
| Testing | Seal and dose verification | Fixed per production |
| Tooling | Format-specific parts | Amortize over volume |
The per-unit cost falls with volume because tooling and testing amortize across a larger run, but the film and the dose remain variable. A buyer should separate fixed from variable cost in the quote and right-size the dose, because over-filling each sachet by a fraction adds up across hundreds of thousands of units. The economics are a reason to lock the dose specification early rather than after the quote.
The Bottom Line
In one sentence a buyer can repeat: single-dose packaging works only when the format, film, seal, and dose are specified and tested, not chosen from a catalogue image. Select the format from viscosity and use, match the film barrier to the active, and name the seal and dose test methods in the order.
At ubitglow, sachet and stick pack filling is specified against seal, dose, and compatibility data, so the single-dose format ships with the tests it needs to hold from filling to opening.