Ingredients Of Glue

Most of us never wonder about the glue ingredients that give glue its sticky character. For sure, almost everyone of us has used some kind of an adhesive or a glue to stick something or the other. But, rarely do we think about glue ingredients, and what goes into making glue. Glue is basically a mix, made of natural or synthetic sources, that binds two surfaces together. The words 'glue' and 'adhesive', though seem to mean synonymous, have different origins. If made from natural sources it is called glue, and if made synthetically is known as adhesive. A glue can bind virtually any kind of material, but they prove their utility when binding thin sheets or layers. For glues to set or cure, they require an optimum temperature. Thermal and electrical conductivity of glue depends on their composition. Let us move on to take a look at glue ingredients.
Ingredients in Glue
Glues are divided as either natural or synthetic depending upon their food ingredients and characteristics. Let us take a look at each glue types one by one:
Natural Glue Ingredients
Ingredients for natural glues are derived from either mineral sources or biological sources such as animals; e.g. casein, or from vegetable sources like natural resins, starch (dextrin) etc.
There are three categories of substances that are called glues i.e. they do not have chemical contents. These three categories are bone glue, hide or skin glue, and fish glue. Technically, other glues are called adhesives, gum, or cement, although most of us tend to use these terms with a generic meaning. Compounds with adhering properties like epoxies, caulks, or sealants are mixed with special additives to impart them suitable properties according to their usage.
Historically, glue was invented when ancient tribes found out that bones, hides, skin and connective tissues of animals could be processed and collagen protein in them can be extracted. Collagen is a sticky protein and has useful adhesive properties. Even today, a huge chunk of glue made all over the world is animal glue, which is manufactured by a process similar to that was used in the past. These days, animal glue is made by soaking the hides in water to produce 'stock' which is then treated with lime to break down the hides. Lime is then separated and the residue is neutralized with a weak acid solution. At around 70 oC, the hides are heated in water. The glue liquor thus formed, is then separated and more water is added. The whole process is repeated with an increase in temperatures. The resultant glue liquor is dried into resin like chipped pellets.
Milk can also be a source, from which glue is manufactured. Casein, a milk solid and blood albumin can also be used to make glue. Dried cow blood serum has albumin, which is heated so as to coagulate it, so that it becomes insoluble in water.
Fish is another source of glue. Fish glue is made from heads, bones, and skin of fish, but it is too thin and is a weak adhesive. Primitive men discovered that air bladders of some fish could produce a much stronger glue that was white and odorless and was named ichthyocol.
Apart from animals, plants can also be used to produce glues. Such a type of a glue is called vegetable glue. This type of glue is water soluble and is made from starch, which is found in vegetables and grains. This segment of natural gum also includes, agar from mixtures in aquatic plants, algin which is deduced from seaweed, and gum arabic which is nothing but an extract of the acacia tree more commonly known as the gum tree. You can also try to learn how to make glue naturally at home.
Synthetic Glue Ingredients
Cyanoacrylate is the main ingredient of synthetic glue also known as superglue. It was discovered by Dr. Harry Coover in 1942, when he was working for Kodak Research Laboratories, towards development of an optically clear plastic for gunsights. Actually Coover first rejected cyanoacrylate because of its high sticky character.
But later he realized that cyanoacrylate was a useful and in 1958 it was marketed and packaged as superglue.
Industrial purpose synthetic glues are called epoxy adhesives. There are two basic components to which various modifying ingredients are added to enhance elasticity and improve there physical and mechanical properties. These additives usually include extenders, filling agents, curing accelerators and diluent. Here is a sample list of the ingredients used while manufacturing synthetic glue:
Low Molecular Weight Epoxy Resin (Modified), Molecular Weight 500; Aluminum powder; Amorphous silica; Sodium carbonate Na2 CO3.10H2O; Sodium chromate Na2CrO4.4H2O; Polyaminoamide (amine number 180-250).
Thus, there are many glue types made of different glue ingredients and it's important to get the right one suitable for your job. Meanwhile newer and more efficient glue are being manufactured every day. The versatility of glues has been proven and scientists are consistently working towards better glue chinafooding ingredients that will make its usage simple and reliable.