Understanding how to choose the right closure for your glass packaging
Closures and components do more than seal a product. They complete the package, ensure compatibility between vessel and formulation, and directly influence how a product is stored, used, and perceived.
The right closure can improve usability, protect sensitive contents, and reinforce product positioning - whether that’s premium, practical, or sustainability-led. From dispensing accuracy to tamper evidence, each component plays a specific role in the performance of the finished product.
This guide outlines the most commonly used closures and accessories across key product categories, explaining their function, materials, and typical applications to help you make informed decisions.
Diffuser Bottle Components
Diffuser bottles rely on a combination of collars, inner stoppers, and reeds to function correctly. Diffuser collars sit at the bottle neck to hold reeds securely while providing a clean visual finish. They are available for both stopper and screw necks and are typically made from plastic or metal, with flat or domed profiles depending on the desired look. Inner stopper inserts, usually made from LDPE or silicone, are press-fitted into the neck to seal fragrance during storage and transport, helping prevent leaks and evaporation before use. Diffuser reeds act as the delivery system for fragrance oil and are available in natural rattan or synthetic fibre options, with length, diameter, and reed count selected based on bottle size and oil viscosity.
Candle Glass Components
Candle closures are primarily used to protect the wax surface, preserve fragrance, and complete the overall presentation. Candle lids are available in wood, metal, or glass and come in flat, domed, or recessed formats, with optional gaskets for a tighter seal. In addition to lids, dust covers are often used to protect candles from debris during handling and retail display, while also offering a cost-effective branding opportunity. Safety and warning discs are included to provide mandatory usage instructions and ensure compliance with fire safety regulations in applicable markets.
Cosmetic Components
Cosmetic jars typically use screw-top lids as their primary closure, securing contents and maintaining hygiene. These lids are available in plastic, aluminium, or bamboo composite materials, with single-wall or double-wall designs depending on the desired weight and feel. Inner sealing inserts provide an additional barrier between product and lid, helping prevent leaks and contamination, and may take the form of press-fit discs or wadding liners. Tamper-evident seals, such as induction or pressure-sensitive liners, are commonly used in cosmeceutical or export-ready products to ensure product integrity at point of sale.
Beverage Bottle Components
Beverage bottles use closures designed to maintain freshness, safety, and shelf life. Twist-off lug caps are widely used for juices, sauces, and functional drinks, creating a vacuum seal and often incorporating a tamper-evident pop-up button. Crown caps are a classic crimp-on option for carbonated or pressurised beverages and require specialist capping equipment. Tamper-evident shrink bands provide additional security by visibly sealing the cap-to-neck junction and are commonly used across both alcoholic and non-alcoholic beverage products.
Aromatherapy & Dropper Bottle Components
Dropper and aromatherapy bottles use specialised closures to control dosage and reduce exposure. Dropper caps combine a pipette, bulb, and collar to dispense measured drops and are available in standard, tamper-evident, or child-resistant formats, with common neck sizes including DIN18, GL18, and 20/410. Orifice reducers offer an alternative dispensing method by restricting flow to single drops and are often used with screw caps. Spray pumps are suited to low-viscosity products such as mists and hydrosols, while serum pumps provide controlled dispensing for thicker formulations. Child-resistant caps are used where regulated or active ingredients require additional safety measures.
Key Considerations When Choosing Closures
When selecting closures, it’s important to ensure compatibility with the bottle’s neck finish, whether threaded, crimped, DIN, or stopper-style. Closure materials should be suited to the formulation type, particularly when dealing with oils, water-based products, volatile ingredients, or high-viscosity formulas. Regulatory requirements such as tamper evidence, child resistance, and safety labelling must also be considered. Finally, user experience plays a significant role, as ease of opening, dosing accuracy, and everyday usability all contribute to customer satisfaction.