by Breana Cronk, IQS Editor
While for many the word ‘adhesive’ may conjure up thoughts of the paste-eating grade school classmate who sat three desks over, adhesives have actually been in use for thousands of years. From their beginnings in the ancient world to their current use in everyday objects, these sticky substances have undergone many changes. The Egyptians, Greeks, Romans, Mongols and other archaic groups used simple and natural formulas to bond surfaces and objects together. These early pastes were not replaced until the 1900s when technological advancements made way for the discovery of powerful synthetic bonding agents. Ironically, current concerns with global warming and climate change just might cause a return to the green ways of the ancients.
Common examples of adhesives.
The earliest recovered adhesives are over 8,000 years old. Found in caves surrounding the Dead Sea, these pastes were made of animal hides and used to repair ceramics. The Egyptians likewise used natural plant and animal materials to adhere two surfaces together. The Greeks and Romans further refined the process using egg whites and milk to create laminating adhesives which hold in place some of their most notable artworks and carvings. These egg, animal hide and plant based adhesives were popular long into the industrial revolution. Soon after, however, the need for stronger and more easily applied adhesives led to the creation of synthetic compounds. Lower costs and ease of production heightened the popularity of adhesives over other bonding techniques such as welding and mechanical fastening.
Rolls of modern laminating adhesives.
Industrial adhesives are ubiquitous in the modern world. Cars, furniture, envelopes, toys and cling wrap list just a few of the seemingly innocuous adhesives frequently encountered. Although these seem harmless, many are made with chemicals and solvents that can be harmful to health and the environment when they break down. Volatile organic compounds and hazardous air pollutants such as methylene chloride are found in many adhesives. The use of such chemical solvents has been proven to deplete ozone when released into the atmosphere, causing serious concern and gaining notice from federal, state and local government agencies. The current onslaught of environmental awareness brought on by fears of climate change and global warming has brought with it intensified regulations and standards in nearly every industrial field. Adhesives are no exception.
Stock forms of hot melt adhesives before the heating process.
While increased adhesive regulations have not necessarily led to the return of animal and plant based bonding agents, they have led several adhesive manufacturers to seek alternatives to the use of potentially hazardous materials and practices. Hot melt adhesives, for example, have eliminated the solvents once needed to create lasting bonds. Epoxy adhesives made with fewer harmful fillers are also made to withstand higher levels environmental and chemical corrosion in order to decrease the release of chemical components. The creation of water-soluble solutions further reduces waste and toxins and often times production costs. Although regulations and increased consumer awareness may have initiated the return to green, benefits such as decreases in shrinkage and dependence on foreign oil as well as improved environmental and worker safety will ensure that improvements continue as will the long history of the adhesives themselves.