Adhesives V Sealants - The Ultimate Guide.

A beginners guide to understanding the difference between Adhesives and Sealants. 

Long gone are the days when you wanted to join or seal two materials and the first thought was to bolt, rivet, or weld. Today there is a wide range of adhesives and sealants that offer a simple solution in both the building and industrial fabrication sectors. In many instances these non-metallic substances are better than traditional single point metal fasteners. Adhesive glues and caulk joint sealants have the ability to bind or seal different materials together, and distribute stress more broadly. They are cost effective and offer an aesthetic improvement over mechanical fasteners with better design flexibility. This is a beginners blog into the world of adhesives, and caulk sealants and how these products make for a more presentable finish.

Before we dive in comparing adhesives and sealants, lets cover the basics. What is the difference between these products? An adhesive or glue is a high strength product for the purpose of joining of two pieces of materials together. It is applied to one surface of two separate items that bind together to resist separation. Whilst a sealant or joint sealant is a low strength caulk product that is perfect for filling and sealing gaps between different materials. Sealants prevent the passage of air and water into openings and accommodate differential movement. This is the basic breakdown; however, you will find there are numerous adhesives that work well as a joint sealant and sometimes vice versa. Understanding your application and the results you are seeking is the most important consideration is selecting the right product.

What are the key advantages of adhesives, and sealant?

Adhesives and joint sealants offer numerous advantages over mechanical fasteners such as rivets or Huck bolts including thermal bonding like welding. 

• Invisible fastening solution for a clean smooth finish compared to traditional fasteners.
• Provide uniform distribution of weight over a larger surface making for a better bond.
• Spreads and absorbs stress better than a single point metal fastener.
• Facilitates and compensates thermal movement between different material types.
• Time & cost effective; better productivity compared to the use of metal fasteners.
• Excellent seal against most elements including moisture, salts, UV light and so much more.  

What are the main types of adhesive glues?

There are numerous types of adhesives with different chemical composition. Also known as glues, cement or paste. In this blog we will be covering the synthetic adhesives that are used in the building and industrial fabrication sectors rather than the natural glues. This is an overview of the range covering  examples of MS Polymer, Polyurethane, Epoxy, Polyamide, and Acrylic etc.

MS Polymer adhesive.

This is the latest generation of high performing environmentally friendly adhesives originally from Japan. They are a hybrid between silicone and polyurethane, with all the advantages of each product and none of their disadvantages. An easy-to-use all-rounder that requires little surface preparation. Examples of this include Aerobolt's structural adhesive range; Bond Flex, and Bond Flex Plus.  Other popular options including Bostik® Xtreme®, Soudal® T-Rex®, and select elastomer glues from Loctite®, Sikaflex® & more. A highly versatile chemical base that works well with just about any material. Highly recommended range for most applications. Medium price range.

Polyurethane Glues & Adhesives.

Polyurethane is another strong flexible adhesive. They bond well to a good range of material including plastic, metal, and timbers, making them very popular in both the construction and industrial sectors. In broad terms, polyurethane has excellent resistance to being stretched and an ability to withstand movement. Examples of this product include Bostik® Matrix® FC, Sikaflex® 252, Sikaflex® 221 and many other products. Low price range.

Silicone Adhesives. 

Select silicones have adhesive properties for a wide range of materials and applications. In the building and construction sector silicone is generally considered superior to polyurethane with some limitations. The big drawback with silicone however, is that it cannot be painted. A great all-rounder is Bostik’s Industrial Grade Silicone.  This product has superior adhesive properties, that works well with numerous materials and is Aerobolt's # 1 silicone with many of our customers in the construction sector. Bostik® V60 is a construction adhesive for painted and anodized aluminum & glass applications. V60 has excellent natural ageing stability and will maintain its elastomeric properties permanently, even under harsh conditions and temperature extremes. The thixotropic nature of this product ensures that it will not slump in typical construction joints with excellent UV stability & long life reliability. 

Epoxy Adhesives.

Epoxy is a two-part adhesive that forms when you mix epoxy resin with a hardener. These two different substances are stored in separate containers and mixed when ready to use. Epoxies are not as flexible as MS polymers or polyurethanes however they have better shear strength with longer open times, allowing for the assembly of complex shapes. Epoxies adhere to a wide range of  surfaces like metals, fibreglass, timber, plastics, stone, concrete etc. Examples of an epoxy include Lord® 310 series, Dunlop® Builders Bond, Selleys® Araldite and many more. High price range.

Dunlop Builders Bond

Selleys Araldite

Acrylic Glue.

World famous Super Glue® is an acrylic glue. There are numerous acrylic adhesives on the market, including MMA's, and cyanoacrylate. Methyl methacrylate adhesives (MMA’s) are a type of acrylic that comprises resin and hardener. When cured MMA’s forms a strong bond with excellent resistance to shear, peel and impact stresses. Examples of acrylic adhesives include Crestabond® M1 series, 3M® Scotch-Weld, Super Glue®, Loctite® H8000 & more. High price range.

3M Scotch-Weld®

Loctite H8000®

Polyimide Glue.

Looking for an adhesive for high temperatures? Polyimide provides excellent thermal resistance in the temperature range 240 – 500 degrees. High price range.

There are numerous other types of adhesives including, white craft glue, yellow timber glue, hot glue, spray adhesive, cyanocrylat (A.K.A Superglue®) etc.

What are the main types of sealant?

A sealant is a low strength product that is perfect for filling and sealing gaps between different materials.The following sealants listed are based on their chemistries make up with each sealant’s suitability to an application is depentant on numerous factors. Some of the popular sealants or sometimes refered to as caulking products include, polyurethane, silicone, MS polymer, polysulfide.

MS Polymer Sealant.

These are newcomers to the sealant world and cure to be fully elastic after curing. Suitable for a wide range of materials, with little surface preparation. Examples of MS Polymer sealants include Soudal® Multibond SMX50 & Bostik® Xtreme Flex. Medium price range.

Polyurethane Sealant.

Polyurethane or PU sealants are tough—even abrasion-resistant caulk sealants that are paintable. They have great adhesion with good movement capability but don't work well with glass. Examples of polyurethane sealants include Aerobolt Seal Flex, Bostik Seal N Flex 1 and Sikaflex® 221 or Sikaflex® 11FC. Low price range.

Silicone Caulk Sealant. 

Silicones are most commonly used used in areas that are prone to expansion and contraction. It acts like a barrier to prevent the passage of air and water, mostly for numerous bathroom & kitchen applications. Silicones are highly flexible and popular in the construction & building sector. They are appealing to most tradie gurus becuase unlike polyurethane do not require follow-up painting.  A popular joint sealer for caulking applications is Bostik 6S Sanitary.  This product has superior resistance to mould and works well with numerous different type of materials associated with bathrooms and kitchens.  

Butyl Sealant.

Butyl sealants are synthetic rubber blend materials that demonstrate a strong adhesion to a wide variety of materials including metal, glass, concrete, timber etc. Butyl forms a tough skin but remains permanently plastic underneath. Ideal for sealing joints in applications such as curtain wall joints, metal panel joints, door frames, drains, windows, or against a neoprene or EPDM surface. Known to withstand vibration and a little difficult to apply, examples of this product include Selleys Butyl Mastic or Bostik’s 5612 Mastic. Low price range.

Bostik® 5612 Mastic®

Selleys® Butyl Mastic

Polysulfide Sealant.

Polysulfide sealants are water & chemical resistant but do not tolerate much movement. Most common in swimming pools and other locations where submersion must be tolerated. Polysulfide sealants often require a primer. They tend to be relatively expensive.

Other sealants include latex, acrylic & silicone which we cover below.

Structural Adhesives, Silicone and Joint Sealant Summary

Today we have covered the product range of adhesives, and sealants. Hopefully, this blog has taken the mystery out of these products and removed any anxiety out of selecting the right product for your application. Here at Aerobolt we have a comprehensive range of structural adhesives, silicones and joint sealant that can assist in your next project, in fact Aerobolt has its very own private label range of high-quality products that perform well in almost any application. Click here to view our range of adhesives and sealants. Alternatively, call or contact us for all your sealant requirements as we would love to assist you. 

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