A) Two-Part Solvent-Free Adhesives

• Each Component by itself is not an adhesive: Must be thoroughly and properly mixed to ensure good long term durability

• Must mix many small packages, instead of using a few large ones: Costs time, money & labor

• Weather sensitive to handle: Short pot life when hot; hard to mix and slow to cure when cold

• Negligible green strength (oily, slippery adhesive before cure): Extensive rolling and sandbagging of seams, often necessary

• More than double empty Part A & Part B containers to discard when job complete

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B)  Hot Melt Adhesives

• Special and costly hot melt equipment and power required  

• Cost more to use because they install slower and require more workers to apply

• Thermoplastic (hardness changes with temperature): become softer and weaker in hot sun, plus harder and sometimes brittle when cold

• Installation sensitive: Often “oozes & squeezes out” of seams on hot days and prematurely solidifies (solid lumps underneath) on cold days

• Sometimes burns installer’s fingers during application and installing

C) One-Part Solvent-Free Adhesives (Both Urethane & Silicone/Silane)

• Usual installation problems previously mentioned with oily, slippery, negligible green strength adhesives: wind, hot, cold, oozing, squeeze-out, passing clouds, sandbagging seams, etc.

• Urethanes: Foam when applied to a damp surface and/or in high humidity; crystallize (become solid) in pail when cold; often need moisture added to speed cure; brittle after cure

• Silicone/Silane: Very slow to cure when cold and need water to hydrolyze in order to start their cure

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D)    Sewing (Mechanical Seam Joining)

• Needles often break due to cold weather and/or wind 

• Spot fastening: Unjoined space between each stitch  

• Easy to vandalize by cutting thread stitches

• Expensive: Sewing machines necessary; slower installations plus more people required