A stick pack is the most honest format in supplements. One sachet contains one dose, consumed immediately, with no scoop, no measuring and no powder sitting open in a humid kitchen. It is also a format where powder behavior, film choice and sealing parameters all have to cooperate, because there is no headroom to hide behind a tub.
The geometry decision comes first. A standard sachet is roughly 30 mm wide by 120 to 160 mm long and holds about 3 to 8 grams of a typical blend. Narrower three-fin packs look refined and reduce film waste but limit dose, while wider four-fin packs hold more and cost more per unit. Ask for the fill weight range in the film width before agreeing a formula.
Powder flow is a harder problem in stick packs than in tubs. A vertical forming machine drops a measured volume into a moving film web, so density variation, static and fine fraction all change the delivered weight. Blends with high hygroscopicity, fine botanical dust or sticky sweeteners need granulation or a changed excipient set before they will run consistently.
Dose accuracy is checked as weight variation across the run rather than in a single sample. A blend that flows acceptably for twenty minutes and then bridges in the hopper produces a drift that looks like a quality failure but is an equipment interaction. A pilot run on the actual machine is the only reliable test.
Barrier film is a specification, not a supplier catalog item. Aluminum foil laminates give the strongest protection against moisture and oxygen; metallized and high-barrier transparent films are lighter visually but weaker over long shelf life. For a product going to a humid market for eighteen months, the film structure belongs in the specification with a stated water vapor transmission rate.
Seal integrity deserves a documented test. Seal width, temperature and dwell time set the burst strength, and a sachet that leaks at a corner delivers a partial dose and a wet powder. Ask what the seal verification method is and at what frequency.
Tearing behavior is a consumer-facing specification. A serrated notch that fails produces a sachet that cannot be opened without shaking powder into a sink. Notch geometry, film thickness and seal placement interact, and a prototype should be tested by hand rather than approved from a drawing.
Flavor masking is more demanding in a single-serve sachet because the entire dose hits the tongue at once. A blend designed for 10 grams in a scoop of water behaves differently when the same 10 grams is taken directly or into a smaller volume of liquid. Serving instructions and sachet weight must be agreed together.
Print and artwork constraints differ from label work. Batch code and expiry are usually printed on the web rather than applied, which means artwork approval happens before film production and a late change costs a printed roll. Design should assume the pack is small, and legibility should be verified on a physical prototype.
Costing arithmetic favors moderate volumes. A 100-sachet box has a materially lower cost per sachet than a 14-sachet trial pack, mainly because of the fill and pack-out cost rather than the film. Trial formats are a marketing decision and should be priced as one.
The format suits probiotics, collagen shots, creatine daily doses, electrolyte blends and caffeine-free energy mixes, which is a real list, and a good stick pack supplement manufacturer will know which of them need granulation before a machine will run them and will say so at the sampling stage.
Ask for the machine's stated fill range in grams for the chosen film width, then design the dose to sit inside the middle of that band rather than at its top edge. A sachet engineered at the maximum fill runs acceptably for an hour and then drifts, which is a specification error rather than a maintenance problem.
