Packaging Archive for cosmetics

Compatibility is confirmed by testing, not by a table. The general principle: formulas with essential oils or high alcohol content attack certain plastics and call for glass or HDPE; extreme pH can react with metal; light-sensitive actives need amber glass or opaque packaging. The standard test is filling the real formula into the candidate pack and monitoring it for weeks under controlled temperature, watching for deformation, leakage, colour change and loss of active.

The neck finish is the standardised measurement of the opening, written as two numbers, for example 24/410. The first is the neck diameter in millimetres, the second is the standard for thread height and pitch. It matters because it defines what fits: a 24/410 bottle accepts any 24/410 cap, pump or valve from any supplier. Choosing the closure before locking the neck is the most common cause of rework.

Start from real use, not a round commercial number. Work out how much product one application uses and multiply by frequency and the duration you want: a serum at 3 drops a day lasts roughly two months in 30 ml. Too large and the product expires open before it is finished; too small and it reads as expensive. With sensitive actives, smaller volume helps, because it shortens exposure after opening.

HDPE is opaque, flexible and has a good chemical barrier, which suits shampoo, conditioner and aggressive or alkaline formulas. PET is clear, rigid and glossy, with a good gas barrier, chosen when the brand wants the product visible, as with oils and toners. In practice: if the formula needs protection and the brand accepts opacity, HDPE. If showing the product is part of the appeal and the formula is stable, PET.

A standard pump has a dip tube reaching the bottom and, at every stroke, lets air in to replace the product removed. Airless uses a piston that rises as the content is used, with no air entering. The difference shows up in two places: preservation, because airless protects actives that oxidise such as vitamin C and retinol; and yield, because airless leaves far less residue. Airless costs more and will not take very thick formulas.

Glass gives a superior barrier, reacts with almost no formula and signals value, but it adds freight weight, breaks and limits shape. Plastic is light, resilient and accepts more shapes and colours at lower cost, but demands attention to chemical compatibility and barrier. Skincare with unstable actives and fragrance usually go to glass. Large volumes, bath products and children's products usually go to plastic.

Definition usually runs in parallel with formula development, and what drives the timeline is part availability. Stock packaging already held by the partner resolves quickly. Made-to-order parts, or anything needing new tooling such as a specific pan diameter, add weeks. That is why packaging selection enters the project early rather than at the end.