What it is
Why you’d need it
Foam liner is a general purpose liner, made of compressible polyethylene foam. These do not create a seal, and is often used for leak prevention.
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.
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 actually performs better than a regular foam liner. Like the foam liner, this also does not create an airtight seal.
It is taste and odor resistant, and has a low moisture transmission rate, meaning it prevents moisture from entering the bottle and affecting product.
Structurally similar to a foam liner, pressure sensitive liners have adhesive on one side, designed to stick on 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.
Pressure sensitive liners provide an extra level of protection in that it actually creates 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.
Pulp and Poly liners have two components: a thin film (polyvinyl) attached to a paper (pulp) material.
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.
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.
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.
Phenolic cone liners are essentially wedge shaped LDPE (low density polyethylene) inserts that seals the lip of the container, while providing extra protection.
Phenolic cone liners are a good option when a leak proof seal is necessary. These are recommended for use on glass bottles, but can also work with plastic containers.
A plastisol liner is unique in that it is actually part of a cap. A plastic gasket lines a metal cap, which creates an airtight seal when heated and then cooled.
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.
Pulp and aluminum liners consist of a polyester film, aluminum foil and a pulp material.
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.
News/Pulp and Solvseal have very similar functions. One is made with newsboard lamination, while the other has pulp board lamination.
These liners are a considered general purpose solvent resistant.