Sealants: A Brief Introduction

In the aerospace industry, sealants play a critical role. So is it any wonder why SkyGeek sells it?

In many ways, aviation served as the driving force behind modern bonding technology. Building planes and propelling them in the air requires weight-saving measures. What would be lighter, metal fasteners or chemical substances? The development of adhesives and sealants not only cuts down on an aircraft’s weight but it also cuts down on costs.

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Sealants – different purposes, different applications. (Courtesy PPG)

We gathered a brief set of useful notes to provide just enough insight on sealants to reinforce their importance.

What is a sealant?

A sealant performs prevention. Preventing what? It prevents things like air, gas, fire, liquid, smoke and even noise from penetrating one surface and traveling to another. Sealants seal, plain and simple.

What are its functions?

To know a sealant is to know its purpose. When two substrates (or more) form a gap, a sealant will fill it. By doing so a barrier is formed as the sealant’s physical properties adhere to the substrates. Once cured, a sealant is designed to maintain its properties for the lifetime of its use and under conditions and environments specified by the manufacturer.

Three forms

According to, sealants are categorized by classes – one component, two-component, and tapes.

One component sealants are packaged in cartridge form and thus require no further equipment during application.

Meanwhile, two-component sealants “require bulk guns and mixing equipment to prepare and apply the sealant, and are typically packaged in separate buckets.” This class of sealant consists of a base component and an activator component. The two are usually mixed for a pre-determined amount of time prior to application.

Finally, sealant tape is characterized by sealant found on flexible backing.

When Compared to Adhesives

Sealants may be grouped with adhesives but they are not identical structurally or chemically. It’s not advisable to swap one for the other since they are not always interchangeable. We have already mentioned the purpose of a sealant but an adhesive’s main duty is to bond surfaces together. That’s it.

Some strong sealants may be considered adhesives. Additionally, sealants are considered really low-strength putties and caulks. So if you want to know comparatively the range of sealant, it falls somewhere between a strong adhesive and a weak caulk.

And while adhesives (bonding), caulks and putties (fill space) tend to perform one purpose, sealants can be applied for multiple reasons. Specially formulated sealants can serve as fire barriers, insulation (acoustic and thermal), or electrical, corrosion, and moisture inhibitors.

Additional Resources

There are many resources available out there to get you started on using sealants on your plane safely and effectively. While this post is by no means meant to be comprehensive that doesn’t mean SkyGeek doesn’t want to supply you with a way to learn more:

PPG Aerospace Sealant Glossary

Tips for Applying Sealants

Benefits of Sealants (and Adhesives)

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About Skylar

Woah! This is Skylar. I am THEE Sky Geek. I like planes, trains, and automobiles, but really just planes. I love aviation and anything related to it. If you shop on our site you will see my mug plastered throughout since I am the official mascot. I enjoy talking to Sandy, Otto, and Mach since they share my passion for flight. Researching for news and events and other information that affects our customers is what I can't wait to nose dive into. The sky's the limitless!