Adhesives

Bonding agents are called adhesives or glues. They may be made from natural substances or artificial materials. They bind together metals, wood, fabric, ceramics, plastics, composite materials, or virtually any material known. Because of the rising price of oil, scientific investigators have begun a search for natural adhesive materials. At the present time, many are known but are not commercially profitable.

Adhesives have been used by humans for thousands of years. The natural glues have varied from region to region because of the limited materials available locally. One of the simplest adhesives has been made from gluten in flour or cornstarch. Other binding materials have been made from natural resins or from animals. Glue from animals is made by boiling the connective tissues to make protein colloid glues. Horses have often been used in modern times as a source of animal glue. This type of glue is commonly used in the bottle-labeling process.

Starch glues are used to make corrugated cardboard. Huge rolls of paper are threaded though machines that precisely set the folds and use starch glues in a hot mixture to produce a flowing volume of cardboard, which is then cut to make various-sized boxes or other products. Many other products, especially paper products, use natural glues.

Bioadhesives are glues made from naturally occurring organic materials. The term also may be used to describe processed natural materials that have been converted into synthetic adhesives. The bookbinding industry has long used animal glues.

Adhesives are used by dentists to bond crowns to stumps of teeth. The temporary binding agents are adhesives, and the permanent ones are cements. These types of adhesives have to be safe for humans because they are used in the mouth of the patient. Other uses include cavity liners and dental cement.

Actors use adhesives to attach wigs, moustaches, beards, and other objects such as fake noses. These types of adhesives have to be a chemical compound that will not harm the skin or be absorbed as a toxin. Some forms of skin adhesives are an alcohol-resin mixture. Spirit gum remover is used to remove the adhesive. These types of adhesives are not likely to last very long because the body sheds skin cells constantly and the adhesive sheds off with the skin to which it is attached, most likely within a few days or a week.

Bandages with adhesive gums are very common, a variety of which are used in medical treatments and are made from natural or synthetic rubber, acrylic, silicon, or other materials. [Page 2]Synthetic adhesives are made from chemicals that have been processed through the necessary chemical reactions to produce the adhesive. Adhesives made synthetically include resins, silicon, elastomeric, thermoplastics, acetate, polyvinyl, polyurethane, and others. The artificial adhesives are designed and sold to meet a vast number of needs. Some are for general use, are nontoxic, and are water-soluble. Children and the general public safely use these types of glues for simple crafts and many other projects.

Some types of synthetic glues may be used to bond ceramic materials such as the broken handle of a coffee mug. Properties have been manufactured into some glues of this type that allow the coffee mug handle to remain bonded even after repeated washings in the dishwasher. Other types or glues have such strength that it is unlikely that the materials will separate once glued together.

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