Glass Sealants: The Versatile Bond

Glass Sealants

Wacker Silicone Sealants
Hiding in every nook and corner of our daily lives are the wonder chemicals categorized broadly as Sealants. Varsha Trehan takes a look behind the glass facades to understand the role of glass sealant products in modern construction.

Window glass insulation is more efficient, paints and coatings hold better and brighter for longer periods, flooring finishes retain their sheen and the exteriors are water-, mold- resistant too. And this is just around the house. Sealant technology has extended the life of heritage structures, increased scope for architectural design by adding flexibility and durability to materials and joints. There is added safety by coating glass facades to make them impact resistant. Insulation properties are enhanced too without added maintenance effort.

Kishor Srinivasan
As modern construction norms focus on durability and safety, use of sealants and adhesives add to reliability of buildings. "Earthquakes and similar events are a serious threat to buildings. Even in regions with a comparably low exposure to natural disasters, structural movement is a general problem. One factor, for instance, is ground compression. This often leads to movement after construction, which may afflict buildings considerably. Temperature is also a problem, especially in regions where seasonal or intraday temperatures vary considerably. So there are a lot of forces which exert stress on a building, and this is especially true for its gaps and joints. Silicone sealants are a reliable way to seal joints against the elements. At the same time, they cushion movements between parts resulting from temperature changes, humidity, shrinkage of construction material, sound, wind and other mechanical shocks," explains Mr Kishor Srinivasan, Manager Sealants & Adhesives, WACKER Metroark Chemicals. In India, WACKER offers three Sealant lines (classic, hybrid, professional), thus providing a wide range of high-performance silicone sealants.

Amit Malhotra
Waterpoof Sealant Crack Filling
Commenting on the increasing presence of Sealants in our daily environment, says Mr Amit Malhotra, Managing Director, McCoy Soudal Adhesives and Foams "Sealants are now used in every part of our daily lives cars, buses and coaches, railway, doors and windows, bathrooms and kitchens, building facades, industries, etc. Every household will be using sealants for DIY (do-it-yourself) repair and maintenance applications very soon. Sealants are and will be indispensable products for a wide range of applications, for two main reasons: problem solving and aesthetical & perfect finishing." McCoy Soudal is one of the largest manufacturers of Sealants, Adhesives and Polyurethane (PU) Foams in the world, with seven manufacturing plants and operations spread in more than 30 countries and products availability in more than 120 countries.

Vidyut N Acharya

"Sealants and Adhesives have played a vital role in the construction industry for the last 30-40 years. The performance of all these sealants can be even seen today with the kind of durability the old structures possess," corroborates Mr Vidyut N. Acharya, Director, Associated Chemicals. Associated Chemicals are known by their Acecoats brand of Construction Chemicals.

Holding it together

Padmadas Nair
In a time when construction projects are becoming taller and faster, installation of glass facades is a popular choice to meet the need for modern architectural design and engineering. While glass products have emerged to meet the challenges of extreme climatic conditions like those in India, sealants are working to hold these facades in a manner that boosts the customer confidence. Speaking of the silicone-based sealants Mr Padmadas Nair, Commercial Manager, Dow Corning India Pvt Ltd explains "Silicones are inherently UV-stable and hydrophobic in nature. Because of this, silicone-based sealants have extremely good weather resistance. This characteristic, coupled with the fact that silicones are durable and remain elastic under extreme weather conditions helps in better insulation and water proofing of buildings and other constructions. Dow Corning's silicone-based materials, created through research and innovation as well as close collaboration with customers, have a history of use of more than 30 years now – this by itself is a testimonial to the durability of silicones."

One Indiabulls Center
"The change in environmental conditions, effect structures to a very large extent. Factors such as waterproofing, adhesion, temperature variation, thermal stability, elongation, UV resistance, hardness shore, shrinkage and tensile strength have a very vital role when it comes to movement related to structures, which can be associated not only due to temperature variation, but with natural disasters as well. Now-a-days, sealants and adhesives are designed in such a manner that it complies with all of the above standards, which are important in the well-being of a structure" affirms Mr Vidyut Acharya.

"Silicone sealants play a major role, simply because of their outstanding properties, their easy handling, and their durability. They can be used for sealing windows, gaps, and all kinds of constructive joints, so they are an integral part of any façade. Silicone sealants meet the high specifications of this application through their excellent property profile – excellent weatherability, UV-, and aging resistance, very good movement capability and long-term functionality. They also exhibit outstanding adhesive strength to both non-porous and porous substrates," adds Mr Srinivasan.

Promoting fenestration

Glass facades are increasingly spotted across the country's landscape. Fenestration is a design and structural element adding value to building elevations. It needs much attention at the construction stage to ensure that insulation from sound, thermal variation, dust and moisture is at high efficiency levels. This is achieved significantly with the inclusion of appropriate sealant products. Recognizing this need, Construction Chemical companies have developed product ranges of adhesives and sealants specific to glass construction applications. "Fenestration includes windows and curtain walls as well as accessories, but also installation, glazing, sun screens, etc.
It is one of the important key players as part of the building shell and essential for achieving the ambitious targets. Innovative fenestration products have a better thermal performance and gain more energy to substitute energy for heating and lighting. The right combination of glazing and products are required to prevent high energy use for cooling and to ensure summer comfort. The whole energy approach for new buildings is very important and the same principles should apply when replacing windows to improve energy consumption of the building. Therefore, McCoy Soudal has launched a special package for the fenestration segment to offer insulation benefits by making them economical, durable and easy to maintain," offers Mr Amit Malhotra.

"The window sector involves several ways of sealing: connection joints between the window frame and the masonry; sealing between glass and frame; sealing and bonding of aluminum windowsills, and profiled glazing. The silicone sealant in the window area has to endure extreme load at all times. This includes substantial temperature changes, variable weather conditions such as sunshine, rain, snow and frost, wind pressure and considerable movements between structural elements made of different materials. The sealant therefore combines the functions of a weatherseal, a seal and a bond. An ideal combination of useful properties makes silicone sealants suitable for all key applications," avers Mr Srinivasan.

Energy optimization

Builders and their clients are taking on their share of energy conservation to save on the costs to their wallet and that of the environment. "Buildings contribute approximately 40% to overall energy consumption; however a properly designed and engineered façade can enable considerable decrease in energy consumption. A well-engineered façade, together with the right usage of silicone sealants and the appropriate selection of glass provides thermal insulation and water proofing which helps reduce energy consumption in buildings. In addition to providing the structural strength to adhere the glass to the substrate, the silicone sealant also provides the flexibility to architects to help design buildings which are aesthetically pleasant and also compliant with safety and sustainability norms" asserts Mr Padmadas Nair.

Hybrid Sealants
Projecting the safety and comfort offered to interiors, Mr Srinivasan details," Silicone sealants used for sealing windows and glass facades in office and apartment buildings help to keep humidity and heat outside. This not only improves the effectiveness of the air conditioning system, but also allows for significantly lower energy consumption without any compromises regarding the degree of living comfort within the building. Wacker's hybrids offer additional environmental advantages. They are based on Wacker's proprietary alpha-silane technology which offers a unique combination of strength and elasticity. At the same time, the alpha-effect permits the formulation of tin-free silicone hybrids – representing a technological leap in user safety. Wacker hybrid line is free of tin, plasticizers and solvents, which is an additional environmental rationale for modern glass facades." Additionally, high performance sealants and adhesives, based on hybrid polymers are completely VOC-free, as with Wacker's Geniosil range. Thus, hybrids and silicone sealants make a significant contribution to the sustainability of glass fenestration technologies.

Getting the best service

Sealants & Adhesive

The key to getting the best service from sealant application and products is considering factors like wind pressures and thermal stresses at the construction stage itself. Choosing the most suitable product is equally important. "Only high quality silicone sealants offer the adhesion and flexibility profile needed for reliable, long-term protection," cautions Mr Srinivasan. Appropriate application procedure, often a simple one, is equally important. "Most important aspect for any product to stick on to a surface is the surface preparation. In order for the bonding to be strong between the surface and the sealant, the surface needs to be thoroughly prepared. Many of the surfaces which are dirty or greasy would hamper the bonding. Therefore, surface preparation is a must for the durability of a sealant. Manufacturers also offer supply and apply service, where for a specialized application or where the product is expensive and the customer does not want to take a risk by adopting a DIY option, a team of authorized and trained applicators are dispatched to execute the work. This service is not offered at a premium rate and is affordable to majority of customers" adds Mr Acharya.

"High attention for detail and finishing are the key to enjoy aesthetics everyday especially with the ever increasing lifestyle expectations. Finishing at 80-90% level is not acceptable. The aim is to strive for 100% perfect finishing and here lies a huge opportunity," quotes Mr Amit Malhotra. McCoy Soudal's McAademy training application center for sealants, adhesives and foams targets training applicants of sealants and foams to deliver perfect finishing with these products.

Help is at hand with manufacturers setting up customer connects with service and educational initiatives. "In order to enable the construction industry to better address concerns around safety and durability, Dow Corning has recently introduced a program called Quality Bond. This is an innovative membership/ certification program for various stakeholders in the construction and infrastructure market, the objective of this program is to ensure world-class standards for structural glazing and insulating glass manufacturers," according to Mr Padmadas Nair.

How simple is it?

Prestige Palladium Chennai
Besides their utility in entire construction projects, sealants are a part of our homes too. Often the temptation for those ‘busy hands' to take up DIY repairs and projects, is strong. Mr Acharya is encouraging in this direction. "Sealants are available in various type of packing. There are pourable sealants as well as gun grade sealants for horizontal and vertical surfaces respectively. The application of sealants has been made very easy with the help of today's technology. Many of the sealants are available in single packs and are solvent free too, which make the application easy and without skilled labor. Sealants can be applied with the help of putty knife, spatula, fingers or a gun. By taking up a DIY option, the finish is not at all affected as on majority of the sealant packing, the surface preparation and method of application is very well explained."

Product simplicity is also offered in the construction process as Mr Srinivasan tells us. "Silicone sealants for construction purposes are room temperature, one-component vulcanizing, so called RTV-1 systems. This means that they cure directly in the joint, once applied. Curing (drying) is triggered by atmospheric humidity. Basically, there are four different curing systems: acidic, neutral, basic, and aqueous. Each type is based on a different crosslinker. Acidic systems release acetic acid upon curing; neutral systems alcohol or oxime; alkalines create amines; and aqueous systems release water while curing. All silicone sealants provide good to very good adhesion to glass. Due to their outstanding adhesion properties, neutral curing sealants are usually preferred, when substrates like metal (e.g. aluminum frames) or plastic (e.g. PVC) are involved."

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