Guide to Liners

Foam liner

Foam liner is a general-purpose liner, made of compressible polyethylene foam. These do not create a seal and are often used for leak prevention.

Why you need it

Foam liners are compatible with many substances and are an economical option. It can also be used to take up room on the top of the cap when the thread of the neck is not high enough to achieve a tight closure.

Best for

• General Purpose
• Household
• Water based products

3-ply Foam liner (F217)

3-ply foam liners are made of three layers: a thin foam core is sandwiched between two layers of LDPE film. F217 is a brand name and tends to be used interchangeably with foam liner. However, F217 performs better than a regular foam liner. Like the foam liner, this also does not create an airtight seal.

Why you need it

It is taste and odor-resistant, and has a low moisture transmission rate, meaning it prevents moisture from entering the bottle and affecting product.

Best for

• Household
• Cosmetic
• Liquor
• Food
• Water based products

Pressure Sensitive Liner (PS-22)

Structurally similar to a foam liner, pressure-sensitive liners have adhesive on one side, designed to stick to the rim of a container. When a container is closed and pressure is applied to the cap (and in turn, the liner), the adhesive becomes activated, which creates a seal.

Why you need it

Pressure-sensitive liners provide an extra level of protection in that they create a seal that sticks to the rim of the bottle. Pressure seals are not considered a form of tamper evident seal. They do not work well with liquids, especially oils. They can, at times, work with thick liquids such as creams and sauces.

Best for

• Dry products
• Dry food / powders
• Thick liquids

Pulp and Poly Liner

Pulp and Poly liners have two components: a thin film (polyvinyl) attached to a paper (pulp) material.

Why you need it

Pulp and poly liners have good chemical resistance, and work well with both oil and water-based products. They are not compatible with bleach or active hydrocarbons. They work well with inert (low acid) products.

Best for

• Cold fill applications
• Mild acids
• Alcohol
• Powders

Induction Liner

Layers of an induction liner consist of pulp (paper material), wax, foil, and a polymer coating. An induction machine is required to apply the liner.

Why you need it

Induction liners are a popular choice when a tamper-evident air-tight seal is needed. It also works well with liquid products. There are variation within induction liners (i.e., only specific liners will work with oils), so testing is necessary.

Best for

• Pharmaceutical
• Food
• Liquid products

Poly Cone Liner

Poly cone liners are essentially wedge-shaped LDPE (low-density polyethylene) inserts that seal the lip of the container while providing extra protection.

Why you need it

Poly cone liners are a good option when a leakproof seal is necessary. These are recommended for use on glass bottles, but can also work with plastic containers.

Best for

• Liquids susceptible to evaporation
• Essential oils

Plastisol Liner

A plastisol liner is unique in that it is part of a cap. A plastic gasket lines a metal cap, which creates an airtight seal when heated and then cooled.

Why you need it

Plastisol lined caps are a great choice for high-temperature applications. The container used must be able to withstand high temperatures, an element necessary to create a vacuum seal. These are typically acid-resistant.

Best for

• Canning
• Hot fill items, such as sauces and preserves

Pulp and Foil Liner

Pulp and aluminum liners consist of a polyester film, aluminum foil, and a pulp material.

Why you need it

These liners have good resistance to hydrocarbon products. However, they do not work with acids or alkalis. These are typically appropriate for food applications, as pulp and foil liners are odor and taste-resistant.

Best for

• Alcohols
• Ketones
• Oils
• Food applications

News and Silite/Pulp and Silite

News/Pulp and Silite have very similar functions. One is made with newsboard lamination, while the other has pulp board lamination.

Why you need it

These liners are considered general-purpose solvent resistant.

Best for

• Vegetable and mineral oils
• Mild acids and alkalis
• Alcohols
• Organic solvents