Plastic cap, 20/410, smooth white

This is a screw cap made of polypropylene (PP) for bottles and vials with a 20/410 neck finish. It serves one purpose, but an important one: sealing the container reliably without any dispensing element. It is ideal wherever the contents are poured out or applied with a cotton pad, and also as a transit closure that the customer replaces at home with a dropper or spray pump. The smooth white surface is neutral, making it compatible with clear, amber, and blue bottles as well as any label. The cap is suitable for use with cosmetic products and also meets technical-grade quality requirements, so it works equally well with cleaning agents, workshop solutions, and laboratory intermediates.

Where the cap finds its use

• Closing finished products – serums, tonics, facial waters, oils, tinctures, and syrups in vials with a 20/410 neck finish, where the contents are used by pouring or applying.
• Transit closure – when a product is shipped with a dropper or pump packaged separately, the plain cap protects the contents during transport and the dispensing element is fitted at home.
• Samples and bulk storage – for larger quantities of samples, intermediates, and work-in-progress batches, a simple cap is more practical and less costly than a dispenser.
• Replacement closure – when the original cap is lost or damaged, simply choose the same neck type.

Material and its behaviour

Polypropylene is lightweight, strong, and resistant to water, ethanol, and common cosmetic ingredients. It does not shatter or corrode, making it suitable even for the moist environment of a bathroom.

For contents with a high proportion of concentrated essential oils, absolutes, or solvents, we recommend checking before long-term storage that the cap does not deform and remains airtight. When hot-filling, allow the contents to cool before sealing to prevent a vacuum forming inside the container that could deform the cap.

Useful things to know when using

The designation 20/410 is a standardised neck finish: the first number indicates the neck diameter in millimetres, the second defines the thread profile and height. The cap therefore fits only bottles with exactly the same designation, even though the difference between similar neck finishes may look negligible to the eye.

Closures with the same neck type and ready-made bottle-and-cap combinations are available in the Handymade range. When assembling your own combination, we recommend verifying the seal integrity and the behaviour of the packaging with your specific formulation.

Fill the bottle to its nominal volume, not to the brim. The headspace below the neck is designed to accommodate the cap and to allow for expansion of the contents with temperature changes. Overfilling causes product to be pushed into the thread when closing, making the cap stick or fail to seal.

Tighten the cap by hand, not by force. A plastic thread only needs to be tightened until it stops; excessive force can damage it and paradoxically worsen the seal. If the cap turns more freely or feels loose after several uses, replace it.

The cap can be reused as long as the thread is undamaged and the surface is clean. For recycling, it belongs with plastics; before disposal, unscrew it from the glass bottle so that both materials can be sorted separately.

Frequently asked questions