What Is Laboratory Sealing Film? A Plain-Language Guide

Last verified: October 6, 2026. Laboratory sealing film is a thin, soft, stretchable wrapping film that clings to itself and to glass or plastic without glue. A small piece is stretched over the opening of a flask, beaker, tube, bottle, or plate and pressed against the rim, where it molds to the shape and forms a light seal. The film is usually supplied as a roll in a dispenser box, with a paper backing that is peeled away before use. It is a flexible, inexpensive, quickly applied cover for a container that needs to be closed against dust, evaporation, spills, or the air, and it is one of the most common small supplies on a laboratory bench.

The problem it solves is the everyday gap between “open” and “properly sealed.” Many containers do not have a lid, or have a lid that does not fit well, or need to be closed only temporarily. Sealing film provides a fast, conformable cover that can be applied and removed by hand in seconds, without tools and without leaving residue from an adhesive. It also makes a convenient wrap for joining two pieces of glassware, labeling or marking, or holding things together briefly. Note that it is a general-purpose product: the right way to seal a particular container depends on what is inside it and for how long.

Who Uses Sealing Film, and Why

• Chemistry and biochemistry laboratories cover beakers and flasks during stirring, settling, or short storage to reduce evaporation and keep dust out.
• Biology and cell culture laboratories seal tubes, bottles, and plates to reduce contamination and evaporation, and to close vessels in a refrigerator or incubator.
• Teaching laboratories, where it is a simple, forgiving cover for student glassware.
• Plant science, soil, and environmental laboratories use it to cover sample containers and culture vessels.
• Field and sampling work, where a quick temporary seal helps keep a sample intact until it reaches the lab.

Properties That Make It Useful

Stretch and cling

The film can be stretched to several times its original length, and as it relaxes it presses against the surface it was stretched over. That elastic recovery is what forms the seal. Warm hands soften it slightly and help it conform and bond.

Water resistance

The film repels water and is a reasonable barrier against moisture and many aqueous solutions, which is why it is used to reduce evaporation and keep humidity in or out.

Flexibility and low cost

One roll covers a great many containers, and each piece costs little. It can be cut to any size and shape and does not require special equipment.

Where Sealing Film Is Not the Right Choice

Its limits are as important as its advantages, and misunderstanding them is a common source of problems.

• Many organic solvents attack it. Common solvents can swell, soften, or dissolve this type of film, and a film in contact with solvent vapor may contaminate the contents. It should not be treated as a barrier for solvents unless the manufacturer says so.
• It is not a gas-tight or airtight seal. It reduces exchange but does not stop it, so it is not suited to long-term storage of volatile or air-sensitive material.
• It is not heat-resistant. Heat softens and deforms it, so it should not be used in an oven, in an autoclave, or near a hot plate. For related thinking about what plastics can tolerate, see which plastics are autoclavable.
• It is not a sterile barrier unless sold that way. A standard roll is not guaranteed sterile, and the film can shed or carry contaminants into sensitive work.
• It can leave fragments. Torn film may fall into open containers, which matters for sensitive analyses.
• It is not a substitute for a proper closure on hazardous material. Where the contents are toxic, volatile, infectious, or pressurized, the container should carry the closure the procedure calls for.

How Sealing Film Differs From Adjacent Equipment

• Sealing film vs. screw caps and stoppers. A cap or stopper provides a firmer, more reliable closure. Film is a lightweight, temporary alternative, useful when a closure is missing or when a fast, removable cover is enough.
• Sealing film vs. adhesive plate seals. Adhesive or heat-applied seals for plates are engineered for plate formats, and many are designed to withstand heating, freezing, or particular solvents. They suit assay and storage plates better than a hand-wrapped film. See what a microplate is for the plates these seals cover.
• Sealing film vs. aluminum foil. Foil tolerates heat and blocks light but does not cling or seal as tightly, and it is used for different purposes, such as covering containers during heating or protecting light-sensitive contents.
• Sealing film vs. household wrap. Household plastic wrap has different composition and contamination characteristics, and laboratory film is the product intended for bench use.

Using It Well, in General Terms

Most of the technique is simple. A piece is cut a little larger than the opening, the paper backing is removed, and the film is stretched slightly as it is pressed over the rim and smoothed down the sides, so that it clings tightly. Warmth from the hands helps it conform. For containers that need a little more security, the film is wrapped around the neck and overlapped on itself. The film is peeled off by hand when the container is opened, and a fresh piece is used the next time. Several habits improve results. Keep the rim clean and dry, because liquid or dust on the surface prevents a good bond. Avoid touching the part of the film that will face the container opening when sterility matters. Use film for short-term covering and a real closure for anything that must stay sealed over days or weeks. Keep film away from solvents and heat. And store sealed containers upright where they will not be knocked, since film does not hold against pressure or tipping the way a cap does. These are general practices and not a protocol, and a given method may specify a different seal.

Practical Notes for Research-Administration and Lab-Management Readers

• Treat it as a consumable with defined limits. Written guidance that spells out where film is and is not acceptable, for example not for solvents or long-term storage, prevents sample losses and avoids damage to cold-stored or valuable material.
• Sample integrity. Evaporation and contamination through poorly sealed containers can quietly affect results. For long incubations, lab managers may specify a different seal for particular workflows.
• Waste. Used film is usually disposed of as ordinary lab waste, unless it has contacted hazardous or biological material, in which case it follows the institution’s rules for that material.
• Storage. Rolls should be kept in their dispenser, away from heat, and covered so the film does not pick up dust or lose its cling.
• Brand versus generic. Several manufacturers sell similar films. Buying by the required properties, such as stretch, thickness, and any sterility claims, is more reliable than assuming interchangeability.

This page is general information, not clinical or safety training. Follow your institution’s procedures and the manufacturer’s instructions for any specific film, container, or procedure.

The Short Version

Laboratory sealing film is a stretchy, self-clinging wrap that provides a quick, removable cover for flasks, tubes, and plates. It works well against dust and moisture loss for short periods, but it is not airtight, not heat-resistant, not sterile by default, and not compatible with many organic solvents. Knowing those limits matters more than knowing how to apply it. For managers, the practical takeaway is to give staff a short written rule on where film is acceptable and where a proper closure is required, so that a convenient bench habit does not turn into a source of lost samples. It is best understood as a convenience for short, low-risk jobs, and the cost of using it where a real closure is needed can far exceed the few cents it saves.

Frequently Asked Questions

What is laboratory sealing film used for?

Covering and loosely sealing flasks, beakers, tubes, bottles, and plates to reduce dust, contamination, and evaporation during short-term use or storage.

Is laboratory sealing film airtight?

No. It limits exchange of air and moisture but is not gas-tight, so it is not suitable for long-term storage of volatile or air-sensitive materials.

Can sealing film be used with solvents?

Generally not. Many organic solvents can soften or dissolve this type of film, and it may contaminate the sample. Check the manufacturer’s compatibility information before relying on it.

Can it go in an autoclave or oven?

No. Heat softens and deforms it, so it is not suitable for ovens, autoclaves, or hot surfaces.

Is sealing film sterile?

A standard roll is not guaranteed sterile. Sterile-packaged products are sold separately for work that needs them.

How is sealing film different from household plastic wrap?

Laboratory film is made for bench use, with stretch and cling suited to glass and plastic rims. Household wrap has a different formulation and is not intended for laboratory work.