Friday, March 30, 2012

Seam Sealants

Seam sealants are chemical adhesives designed to protect joints hermetically against moisture, gas and thermal intrusions. Various kinds of sealant are available for a wide range of products, although they are typically used astiling and automotive seals.

Seam sealants are often made of polymer so that they expand while setting, filling out the seal and solidifying the connection. Seam sealants are typically used on vinyl flooring and sheet steel connections, such as in automotive applications. Seam sealants are usually available in tubes with spray/swirl applicator heads or as spreads intended for use with a brush or spatula. Application is designed to be simple so as not to require a lot of time or a specific skill set to use. Some seam sealants require 24 hours or more to set, while others set much faster and are ready for paint in twenty minutes.

Polyurethane Sealants

For automotive applications, different metal sheet units are attached and cemented together with seam sealants. Seam sealant spread and tape are available for trunks, drip rails, core supports, roof seams, cowls and many other areas. Seam sealants must be applied during various phases of automobile construction and maintenance, such as initial assembly and restoration projects. Sealants prevent smoke and moisture from entering the car interior or motor area.

Typically, automotive seam sealants are applied with a cartridge gun which resembles a caulking gun. For non-bodywork areas, bush-applied sealants can be used. Automotive seam sealants often set much faster than other types of seam sealants so that primer or paint coatings can be applied.

Polyurethane sealants are also commonly used in building construction, appearing in metal roofing, coping joints, vents and parapet walls and around window openings. Like automotive sealants, these construction sealants are also paintable after a short set time, but they also come in a variety of colors, including clear.

Epoxy Sealants

Sealants used for floor tiling are often made of epoxy, a combination polymer, or copolymer, that features sticky resin and a polyamine hardener component. Epoxy can be applied with special cartridge guns or with paint brushes or spatulas, and generally takes much longer to set than automotive examples. While some floors are laid without the use of seam sealants, sealants can help prevent moisture seep beneath the tiling which causes warping. The hermetic seal created by the sealant keeps out moisture, maintaining a level flooring, and also prevents dirt and bacteria from lodging between tiles, making clean up easier and more health efficient.

Once set, epoxy sealants create a very strong bond between structural elements. Because of this strength and their water-resistant properties, epoxy sealants are used in other applications that might come in contact with water, including technical and recreational marine products. Surfboards feature fins attached with epoxy adhesive sealants, while robot submersibles use epoxy sealants for waterproofing sensitive electronic parts. Epoxy sealants are also used in printed circuit boards designed to protect the electronic components from moisture.

General Sealant Recommendations

Sealant application requires minimal preparation, but the set-up steps are important to ensure a level, adhesive, and strong application. Seams needs to be cleared of dirt and other build-up to enable the sealant to properly bond to the surface of the seam and the sites of the materials being sealed. Additionally, moisture and gas must be absent during applications, because these elements can have unwanted effects on the sealant setting process. Moisture can cause the sealant to remain tacky and refuse to set firmly. Temperature is also an important factor in sealant application. If an application environment is too hot, usually in excess of 120 degrees Fahrenheit, the sealant remains tacky and will not set, while cold temperatures can make the sealant too hard to spread or apply.

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