Choosing The Right Adhesive

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Trivia To Contemplate
  • Dinner guests in medieval England were expected to bring their own knives to table – hosts did not provide them. The fork did not appear until the sixteenth century, and fork-and-knife pairs were not in general use in England until the seventeenth century.
  • According to 1903 issue of "The Old Farmers' Almanac," the best time of the day to select a new pair of shoes is in the afternoon, when the exercise of the day has stretched the muscles to their largest extent.
  • It takes 100 centimos to equal one bolivar, which is Venezuela's basic unit of currency. According to sources, Venezuela is the only country that uses the bolivar as its basic legal tender.
  • Australia’s Great Barrier Reef stretches for 1,242 miles along the coast of Queensland. It is a chain of small islands and more than 2,500 reefs.
  • Dolphins do not breath automatically, as humans do, and so they do not sleep as humans do. If they become unconscious, they would sink to the bottom of the sea. Without the oxygen they need to take in periodically, they would die.
  • He who laughs last thinks slowest!
  • Oman's economy is based on petroleum, which accounts for 99 percent of export revenues. It is located at the eastern bulge of the Arabian peninsula.
  • It takes a ton of ore to produce one gold wedding ring.
  • During World War II, the U.S. Navy commissioned the world's first floating ice cream parlour for service in the Pacific theatre. This concrete barge, capable of producing ten gallons of ice cream every seven seconds, kept ships well supplied.
  • Employees of the Vatican pay no income tax.

The term glue properly refers to pure animal or vegetable glue. Other types, which are resin based, are known as adhesives. The success of your gluing depends on choosing the right kind of glue for the job. The glue or adhesive you use will depend on the type of wood you want to join together, the surface con­ditions, the kind of stress the join will be subjected to and whether a temporary or permanent join is wanted. Pay particular attention to the temperature in the workshop. Most adhesives need a warm atmosphere in which to set. Make allowances too, for hard or resinous woods: these require a sap-resistant adhesive.

[edit] Polyvinyl acetate adhesive (PVA)

PVA adhesive ('white glue') is among the most useful for general-purpose woodwork. Available ready mixed in easy-to-use plastic bottles, it is applied directly to the wood which is then cramped. At normal room tempera­tures, the setting time varies from 30 minutes to three hours depending on the brand used.

PVA is a strong adhesive. It does not stain timber but, if smears are left on the surface, it will show through varnish as a light patch. So any smears must be wiped away quickly with a damp cloth. It is not completely waterproof, although outdoor grades are available, and will not adhere very readily to resinous or very hard woods such as teak.

[edit] Urea formaldehyde adhesive

This is a good adhesive for hard, resinous woods. Its gap-filling proper­ties also make it ideal for gluing loose-fitting joints—such as those found in furniture making and repairs. It resists moisture better than PVA.

[edit] Resorcinol formaldehyde

This woodwork adhesive provides the greatest strength and is the most water resistant, so it is ideal for out­door work and boat building. It is also a good gap-filling adhesive. When adhesives have to be applied to timber treated with preservative, use urea formaldehyde or resorcinol.

[edit] Animal glue (Scotch glue)

This old fashioned glue is made from animal pelts and bones. It comes both in cake or granular form and in liquid form. The cake or granular varieties need to be melted down in a glue pot with water at a temperature of 65°C and used while still hot. These do not stain timber and dry to a medium brown colour which matches most polished or stained woods. They are not waterproof.

Unlike the granular variety, liquid animal glues can be used cold. Again they are not waterproof and do stain some woods, especially oak, so excess glue should be wiped off with a damp cloth before it can do any damage to the wood. Animal glue has largely been made obsolete by more modern adhesives but is still the best to use when con­structing frameworks for upholstered furniture. The stresses which the frame undergoes while being uphol­stered may cause adhesive made joints to fracture.

For mending or renovating antique furniture, use a sapwood based Scotch glue. This has the same expansion and contraction rate as old-fashioned Scotch glue, which is different from that of modern adhesives. Never mix old and new glue on one piece of furniture.

[edit] Synthetic resin cements

This type of adhesive is almost com­pletely waterproof and comes in a variety of forms, powder, semi-liquid or two-part (adhesive and hardener). It can be used for outdoor work and small boat-building. The setting time depends on the temperature of the surroundings—the warmer the air around the work piece the faster it sets.

[edit] Impact (or contact) Adhesives

Wood stuck to wood with this type of adhesive tends to move after a time. It is therefore not strong enough for furniture making and is better suited to fixing laminates and tiles.

The surfaces to be stuck together are both coated with the impact adhesive and are then left to dry separately according to the manu­facturer's instructions. Afterwards, the two surfaces are brought together to make an instant, strong bond. Impact and contact adhesives are the only types which do not require cramping while they set. But as a bond is formed instantly, you should ensure that the mating surfaces are aligned.

[edit] Epoxies

Almost any material can be stuck with epoxy adhesives but for woodworking, PVA and formaldehyde adhesives often prove to be both cheaper and easier to use. Epoxies are made up of two parts —a resin and a hardener—which must be mixed together. Setting time can vary between one hour and 24 hours.

[edit] Cyanocrylate Adhesives

Extra care must be taken when using these 'super glues'. Manufacturers claim that one small spot of the adhesive and a little pressure will stick almost anything to anything in moments, although they don't stick wood well. They will certainly stick skin to skin, so be careful and make sure that children do not get anywhere near them.

[edit] Safety Precautions

Many adhesives are highly flammable and some also give off toxic fumes. Make sure that you work in a well ventilated space and that there are no naked flames' about.

Anyone who is prone to dermatitis should wear gloves or a barrier cream as glues contain skin irri­tants. If the glue should get on to unprotected skin and cause burns or an allergy rash, seek medical advice. If it gets in your eyes, wash it out with plenty of warm water and, again, seek medical advice.

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