Spray adhesive‘s core bonding mechanism relies on "physical penetration"—seeping into the microscopic pores of soft, porous materials (like sponges, fabrics, and leather backs) to form thousands of microscopic "anchor points" (essentially "growing" inside the material). Conversely, smooth, hard surfaces like phone cases and rubber outsoles lack these pores, causing the adhesive to float on top and fail instantly. Every adhesive has its specific purpose; it only delivers true value when used in the right application.
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