Think of sticky packing tape that seals a box instantly upon contact and mild pressure. The adhesive on that packing tape is a “pressure sensitive” adhesive that will adhere to many types of difficult substrates. Applied to a substrate hot and allowed to cool, HMPSA are generally formulated with various synthetic rubbers that can create a product from extremely tacky to very little tack such as “fugitive” or” booger glue.” That’s the glue that holds your credit card to the paper insert when you get one in the mail. It has so little tack it will not tear the paper! Most applications require much higher tack levels to hold an infinite number of substrates together. Typically, high heat is it’s enemy because they have low melt points and can lose adhesion due to heat exposure. Many HMPSA are formulated with higher heat resistance and various peel or shear strength, so choose wisely.