ENVIRONMENT
Environment is a very simple selection criterion. We can divide products in two groups: indoor products and outdoor products, although some can be used both indoors and outdoors. Product labels clearly indicate which group they belong to. Note that 75% of sealants are used outdoors while 25% are used indoors.
Indoor Environment
Key factors of the indoor environment are dirt and moisture, particularly in kitchens and bathrooms. When selecting an indoor product, temperature does not play a major role. On the other hand, the odor and toxicity of the fumes emitted by products while they dry are major selection criteria. It is therefore preferable to select water-based products.
Outdoor Environment
Outdoor products are designed to withstand more extreme environmental conditions than indoor products. The main enemies of outdoor sealants are temperature fluctuations, the sun and moisture, while those of outdoor adhesives are temperature fluctuations and moisture.
Sunlight breaks down the binders used in sealants, making them lose their elasticity, and while humidity reduces the durability of some water-based sealants, temperature fluctuations contract and expand outdoor material, especially metal and synthetic material. If the elastomer sealant lacks flexibility, it can crack. If the adhesive is not flexible enough, the material can come unglued.
The ideal temperature for applying water- and solvent-based products is between 15°C and 30°C (59°F and 86°F).
Sealants: How do temperature fluctuations affect materials?
Material dimensions vary with temperature fluctuations. When the temperature goes down, materials contract and they shrink; sealants must adjust by expanding. On the other hand, when the temperature goes up, materials expand and they get larger. Sealants are then compressed. Sealant elasticity is therefore a prime concern.
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Some materials are subject to larger thermal movements than others. The
following chart shows length variations observed on 10-foot long pieces
of material.
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