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July 22, 2016 - Building & Construction

Understanding One-Component vs. Two-Component Sealants for Building Construction Projects

Sealants offer a range of applications in both the commercial and residential construction markets. From sub-floors and stairs to windows and roofs, choosing the right product is vital to ensuring safe and proper installation. Currently, there are two types of sealant technologies on the market: one-component and two-component. Let’s take a closer look at each type.

One-Component Sealants

Offering general sealant use for a range of applications, one-component sealants are composed of one base component and do not need to be mixed with anything prior to application. One-component sealants:

  • Offer ease of preparation prior to installation
  • Require exposure to moisture in the air to cure
  • Cure from the exposed surface down

One-Component Packaging 

While traditionally sold in cartridges, one-component sealants can now be packaged in sausages. These sausages can reduce the amount of container waste and time needed to replace the product by half. This packaging also:

  • Is composed of a foil type product, which offers better moisture resistance than traditional cartridges (which are made of paper or cellulose components)
  • Allows for one sausage to be used over a broad spectrum of joint sizes or applications, since it can use nozzles with various sized openings.

window and door adhesive

Two-Component Sealants

Two-component sealants are typically used for waterproofing applications. Composed of a base component and activator component, these sealants require mixing equipment for preparation and application. Most of the time, two-components are colorless, and a color pack must be added separately. These sealants:

  • Cure quickly and uniformly without exposure to atmosphere
  • Have extended shelf life
  • Are often colorless
  • Offer wider color availability via a color pack in smaller sealant amounts (sometimes as little as 1 unit or 1.5 gallons of sealants or increments of the same)

Two-Component Packaging 

Typically, two-component sealants are sold in industry standard, unit cans that yield about 1.5 gallons of product each. The can contains the base material, and nested upon it is a second container for the curing agent (i.e., the “b-side)”. The two must be mixed together fully in order to ensure proper curing. Once mixed, the product is expelled into a bulk gun, which can accommodate various sized nozzles to correctly install the sealant into joints.

For certain applications, two-component sealants can be packaged by the manufacturer into special cartridges with static mixers that mix the product as it is gunned. This saves time, since there is no need to manually mix the parts together.

When to Choose a One-Component or Two-Component

While both one-component and two-component sealants largely serve the same purpose in construction projects, several factors determine when to choose one over the other.

Joint Size 

Typically, manufacturers will recommend that two-component sealant when joints are greater than ¾ inches wide. Additionally, the specification may require a two-component due its curing properties in larger joints.

 Skin and Cure Times

Overall, the curing rate is relative to the technology and atmospheric conditions (temperature and moisture source). A sealant’s cure time is also dependent upon the location of the joints and their mass, width and depth. It’s important to be aware of the amount of open time (work life) you have before deciding to use a one-component or two-component sealant.

Application Needs

As a general guideline, one-component sealants are used in joints less than ¾” in width, where specified and by trades not properly trained to mix and install two-component products.

Typically, two-components are for larger projects due to their volume. Professional waterproofers often prefer this type of sealant.

Key applications for both one-component and two-component sealants include:

  • Perimeter joints
  • Expansion joints
  • Sealing dissimilar building materials

Bostik offers a full line of one and two-component sealants for a range of applications. For more information, call 800-7-BOSTIK, or visit www.bostik-sealants.com.

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