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Why Silicone Sealants are Better than Organic Sealants in Exterior Applications

We have so many encounters from people who are very eager to use the cheapest material for their projects. In selecting the sealant to use for their projects, some are very eager to buy an organic sealant due to its attractive pricing. However, sealants play a major role in construction as they are used to seal a gap to prevent water seepage or as a structural adhesive to bond two substrates together. Hence, selecting the cheaper sealant just to save upfront project costs and in turn become a severe headache in future repairs.

The Two Types of Sealants

Broadly speaking, there are organic sealants and also inorganic sealant. Majority of the sealants we could probably buy from hardware store are organic sealants. However, for organic sealants we have silicones. DowSil sealants, which is what Calfeutrage MJM et Fils uses, are purely based on silicone chemistry.

Organic Sealant Inorganic Sealant
Polyurethane Silicone
MS Polymers

After long UV exposure

DowSil CWS

The picture depicts what happens to silicone sealant (on the left) and polyurethane sealant (on the right) after it has been exposed to UV for years. The test was subjected to accelerated weathering. As you can see, the silicone sealant remains unchanged under UV, whereas organic sealant will degrade and exhibit crack especially when there is movement. In the case of weatherproofing sealant, water will eventually infiltrate the building through the cavity. If the organic sealant is rigid, it will chip the substrate where the organic sealant is adhered to. For the case of structural sealant, this can lead to loss of adhesion and the glass panels might fly off the building.


Despite the price difference of organic sealants compared to silicone sealant, it is a wiser choice to go for silicone sealant such as DowSil CWS. It will allow you to have an assurance and peace of mind that the sealant you’re using will not lose adhesion or cause water seepage due to UV degradation. Especially with DowSil sealants and the support that Chain Glass gives as a technical distribut, you can be assured that when it comes to sealant performance, you will be worry-free.

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