Chemistry Matters!

There are two main types of silicone formulations that are used in construction sealants and coatings – alkoxy-based silicone and oxime-based silicone. Alkoxy and oxime refer to the curing technologies used, and there are some big differences between the two.  

Momentive only offers alkoxy-based silicone construction sealants and coatings and has deliberately excluded oxime chemistry from the entire portfolio. We believe that alkoxy provides clear benefits in terms of safety, performance, and application benefits.  

Here’s why.

Safety Concerns with Oxime Chemistry

The primary reason Momentive deliberately avoids offering oxime-based silicone is safety.  

Oxime silicones release MEK / MEKO (Methyl Ethyl Ketoxime) as they cure which is a suspected carcinogen known to carry health risks. In March 2022, the European Union classified MEKO as a Carcinogen Category 1B. When it comes to applying roof coatings or sealants, there is a risk that applicators breathe in this MEKO.

MEKO is acknowledged as a chemical of concern in certain regions around the world. Restrictions, regulations, and guidelines around its use are already in place in Europe and Canada, and other regions look likely to follow. Momentive’s alkoxy-based silicone coatings and sealants release methanol as they cure. This is safer for those applying it.

Using alkoxy-based chemistry is one reason Momentive construction sealants and coatings can be applied without the need for specialized PPE. This isn’t just more time and cost-efficient – it can also deliver real practicality and safety benefits for applicators, especially in hot summer temperatures.

Contractors working on metal roofs in high temperatures during the summer months don’t want to wear any more clothes or PPE than they have to, as it can get very hot and uncomfortable. If they use oxime-based solutions, they should wear PPE, which may increase the risk of discomfort, dehydration, or heat-related illness.  

Despite these concerns, most of our competitors still use oxime chemistry. By choosing Momentive alkoxy-based solutions, you’re choosing a safer product for your projects.

Performance Benefits of Alkoxy Chemistry

Choosing alkoxy-based silicone sealants and coatings also offers several benefits when it comes to application and product performance.
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‍Primerless adhesion

Momentive’s alkoxy chemistry enables many of our coatings to offer primerless adhesion to a range of different substrates and materials. Oxime-based solutions require primers to stick effectively to many substrates. Applying a coating without a primer provides several advantages – it saves time and resources while reducing the chance of product failure due to compatibility issues between substrate, primer, and coating.
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No mixing

Another key benefit of alkoxy based construction coatings is that they do not need to be mixed. Oxime based coatings may separate over time, creating an inconsistent color or consistency. This means the product needs to be remixed or stirred before application to ensure an even finish. In addition, prematurely cured material can form inside the pail - which can cause application issues if rolling or spraying. Check out this video comparing Enduris™ roof coatings to competing solutions for examples of this.  

Momentive alkoxy based coatings do not separate in the same way, which means less risk of premature curing, an even consistency and no mixing required.  

The lack of mixing saves time and labor costs, while also reducing the risk of poor application results.  

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‍Versatility

Alkoxy-based solutions can also be more versatile, especially regarding repairs, restoration and recoating. Momentive alkoxy coatings can be used to recoat old silicone, whatever the chemistry of the original coating – in fact, customers have been recoating and restoring buildings using our products since the 1960s! Oxime-based silicones can have problems adhering to aged silicone and other silicone chemistries.  

This is particularly important in applications such as roof coating – alkoxy chemistry helps to ensure our Enduris roof coatings can be used to repair, restore, and recoat roofs that have already had a roof coating applied.  

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‍Increased elongation

Our alkoxy chemistry offers significantly better elasticity than Oxime-based solutions. This flexibility helps Momentive silicone coatings and sealants to resist building movement, so they stay sealed and watertight over the long term. Oxime silicones simply don’t “stretch” as well, increasing the risks of tears, gaps, and leaks.  

This is particularly important for applications where there is a lot of movement in the joints, like structural glazing for tall buildings.  

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‍A longer cure

Typically, oxime-based solutions cure (skin over) a little faster than alkoxy-based silicones. A longer cure means that the product is workable for longer. This can be beneficial when sealing joints around window frames and doors, as it allows the applicator to seal longer runs before tooling.  

This might mean they can apply SilPruf™ Weatherseal sealant around the entire window or door frame, then tool the whole thing. With oxime-based solutions, you might have to do this in sections.  

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Proven Innovation - Why Choose Momentive

It’s a story as old as our company – and has been happening in the construction industry for decades. Where Momentive innovates, our competitors follow!

Our competitors are finally waking up to the benefits of alkoxy chemistry. With potential regulation on the horizon, they are beginning to release their first alkoxy-based solutions.  

However, most of their portfolios are still Oxime-based. As they learn new alkoxy chemistry and release their initial formulations, Momentive will continue to build on decades of research and successful real-world applications for our proven alkoxy chemistry.  

We’re developing new Solutions for a Sustainable World™, including new construction sealants and coatings for the entire building envelope, from street level to the skyline.

Take our latest Enduris™ 3525 white roof coating, which has just been tested by the Cool Roof Ratings Council (CRRC). By reflecting the sun and reducing thermal emittance, it is proven to reduce buildings' internal temperatures, cut summer cooling costs and energy use, and reduce a building's carbon footprint. 

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Momentive: Global Industry Leader in Silicones for Building

‍Momentive offers a family of world-class, high-performance, 100% silicone sealants and coatings for the whole building envelope. These solutions extend the life and enhance the performance of all kinds of buildings worldwide.

Looking for sealants and coatings for your next project?

Find your nearest distributor at https://siliconeforbuilding.com/distributor-finder, or contact our team today at https://siliconeforbuilding.com/contact.