Glossary A - L
GLOSSARY  A Through L

A  B  C  D  E  F  G  H  I  J  K  L

A

Abrasion resistance - Resistance to wear resulting from mechanical action on a surface.

Accelerated aging - A set of laboratory conditions designed to produce in a short time the results of normal aging. Usual factors included are temperature, light, oxygen and water. In recent years, the adhesives industry has come to rely more and more on the "oxygen bomb" test as an indicator of relative life expectancy of a given formulation.

Accelerated weathering - A set of laboratory conditions to simulate in a short time the effects of natural weathering. Most adhesives are generally not subjected to the conditions that are normally considered under weathering tests.

Accelerator - An ingredient used in small amounts to speed up the action of the hardener in a two-part adhesive.

Acetone - A very volatile and flammable solvent that is particularly useful for cleaning metal substrates.

Adhere - To cause two surfaces to be held together by adhesion.

Adherend - A body which is held to another body by an adhesive.

Adhesion - The state in which two surfaces are held together by interfacial forces which may consist of valence forces or interlocking action, or both.

Adhesion, mechanical - Adhesion between surfaces in which the adhesive holds the parts together by interlocking action.

Adhesion, specific - Adhesion between surfaces that are held together by valence forces of the same type as those which give rise to cohesion.

Adhesive - A substance capable of holding materials together by surface attachment. Same as cement.

Adhesive failure - Type of failure characterized by pulling the adhesive loose from the substrate.

Adhesive, assembly - An adhesive that can be used for bonding parts together such as the manufacture of a boat, airplane, furniture, and the like.

Adhesive, cold-setting - An adhesive that sets at temperature below 68F (20C).

Adhesive, contact - An adhesive that is apparently dry to the touch and which will adhere to itself instantaneously upon contact; also called contact bond adhesive or dry bond adhesive.

Adhesive, dispersion - A two phase system in which one phase is suspended in a liquid.

Adhesive, foamed - An adhesive, the apparent density of which has been decreased substantially by the presence of numerous gaseous cells dispersed throughout its mass. Same as cellular adhesive.

Adhesive, heat activated - A dry adhesive film that is rendered tacky or fluid by application of heat or heat and pressure to the assembly.

Adhesive, hot melt - An adhesive that is applied in a molten state and forms a bond on cooling to a solid state.

Adhesive, hot-setting - An adhesive that requires a temperature at or above 100C (212F) to set.

Adhesive, intermediate temperature setting - An adhesive that sets in the temperature range of 31-99C (87-211F).

Adhesive, pressure sensitive - A viscoelastic material which in solvent-free form remains permanently tacky. Such a material will adhere instantaneously to most solid surfaces with the application of very slight pressure.

Adhesive, room temperature setting - An adhesive that sets in the temperature range of 20-30C (68-86F).

Adhesive, separate application - A term used to describe an adhesive consisting of two parts, one part being applied to one substrate and the other part to the other substrate and the two brought together to form a joint.

Adhesive, solvent - An adhesive having a volatile organic liquid as a vehicle.

Adhesive, solvent activated - A dry adhesive film that is rendered tacky just prior to use by application of a solvent.

Adsorption - The action of a body in condensing and holding gases and other materials at its surface.

Aging - The progressive change in the chemical and physical properties of a sealant or adhesive.

Aliphatic resin glue - Yellow glues which provide more grab for shorter clamp times, and offer better water resistance and heat resistance than traditional white glues.

Ambient - Usual or surrounding conditions.

Ambient - Usual or surrounding conditions.

Ambient temperature - Temperature of the air surrounding the object under construction.

Ampere - A unit of electric current. One ampere flows through a conductor having a resistance of one ohm, when there is one-volt difference between the ends of the circuit.

Anaerobic - Adhesives that cure in the absence of oxygen.

Assembly - A group of materials or parts, including the adhesive, which has been placed together for bonding or which has been bonded together.

Assembly Time - Also called Open Time. The time period from the application to adhesive until the final application of pressure. This term includes both Closed and Open Assembly Times.

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B

Batch - The manufactured unit or blend of two or more units of the same formulation and processing.

Binder - A component of an adhesive composition that is primarily responsible for the adhesive forces that hold the two bodies together.

Blister - An elevation of the surface of a substrate, somewhat resembling in shape a blister on the human skin; its boundaries may be indefinitely outlined and it may have burst and become flattened.

Blocking - An undesired adhesion between touching layers of material such as occurs under moderate pressure during storage or use.

Bond - To join two structures together; to create an assembly through adhesive linkage; the completed assembly.

Bond face - The part or surface of a building component which serves as a substrate for an adhesive.

Bond Strength - The unit load applied in tension, compression, flexure, peel, impact, cleavage, or shear, that is required to break an adhesive assembly with failure occurring in or near the plane of the bond.

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C

CA - Cyanoacrylate Adhesive

CAS Number - Chemical Abstracts Service. An assigned registry number to identify a material.

Catalyst - A reactive material added to accelerate adhesive drying. Substance added in small quantities to promote a reaction, while remaining unchanged itself.

Cellular material - A material containing many small cells dispersed throughout it. The cells may be either open or closed.

Chalking - The preventing of the proper coalescence of the adhesive film due to low temperatures of the air, wood or adhesive.

Checking - The formation of slight breaks or cracks in the surface of the adhesive.

Chemical cure - Curing by chemical reaction. Usually involves the cross linking of a polymer.

Chemtrec - Chemical Transportation Emergency Center. Provides emergency information on materials involved in transportation accidents.

Clamp time - The time that the substrates being glued together need to remain clamped.

Clamping Force - The total force exerted by a clamping device on a glue line.

Closed Assembly Time - Period of assembly time when the adhesive film is not exposed to the air, but prior to the time that pressure has been applied.

Closed cell - A cell enclosed by its walls and therefore not connected to other cells.

Cohesion - The molecular attraction which holds the body of an adhesive together. The internal strength of an adhesive.

Cohesive failure - The failure characterized by pulling the body of an adhesive apart.

Cohesive strength - The ability of the adhesive to stick within itself during the wet stage. The term cohesive strength also applies to the internal strength of dried adhesive.

Cold pressing - A bonding operation in which an assembly is subjected to pressure without the application of heat.

Combustible - Materials that will burn.

Condensation - A chemical reaction in which two or more molecules combine with the separation (or release) of water or some other simple substance. If a polymer is formed, the process is called polycondensation.

Crazing - The formation of fissures or voids in the adhesive film due to excessive shrinkage characteristics of the adhesive.

Creep - The deformation of a body with time under constant load. Also called cold flow.

Cure - To set up or harden by means of a chemical reaction.

Cure Time - The period of time required to attain a full cure.

Curing agent - A chemical that is added to effect a cure in a polymer. Same as hardener.

Curing time - The time needed to cure or "set" an adhesive.

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D

Delamination - The separation of layers in a laminate because of failure of the adhesive, either in the adhesive itself or at the interface between the adhesive and the substrate, or because of cohesive failure of the substrate.

Density - Ratio of weight (mass) to volume of a material - i.e. grams per cubic centimeter or pounds per gallon.

DOT - Department of Transportation (US).

Dry - To change the physical state of an adhesive or a substrate by the loss of solvent constituents by evaporation or absorption, or both.

Drying Time - The interval of time between the point of liquid adhesive application to the adherent substrate and the time at which adhesive particle coalescence occurs.

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E

Edge gluing - The bonding of the edge grain of wood strips to make a wider board.

Elasticity - The ability of a material to return to its original shape after removal of a load.

Elastomer - A rubbery material which returns to approximately its original dimensions in a short time after a relatively large amount of deformation.

Emulsion - A dispersion of fine particles in water.

Equilibrium Moisture Content - The moisture content eventually attained in wood exposed to a given level of relative humidity and temperature.

Evaporation Rate - The rate at which a material will vaporize compared with a known substance.

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F

Face Gluing - Gluing of heavy wood stock on the wide face to attain a thicker panel.

Failure, adhesive - Rupture of an adhesive bond such that the separation appears to be at the adhesive substrate interface.

Fatigue failure - Failure of a material due to rapid cyclic deformation.

Fiber Saturation Point - The moisture content of wood at which all unbound moisture has been eliminated. This is typically about 30% Moisture Content.

Filler - Finely ground material added to an adhesive to change or improve certain properties.

Fire Point - Lowest temperature that a liquid will produce sufficient vapor to ignite and continue to burn

Flammable - Describes any material that will ignite easily and burn rapidly.

Flash point - The lowest temperature at which the vapors being given off by a substance can be ignited.

Freeze/thaw stability - The ability of a product to remain usable after it has been frozen and thawed.

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G

Gel - A semisolid system consisting of a network of solid aggregates in which liquid is held.

Glue - Originally, a hard gelatin obtained from hides, tendons, cartilage, bones, etc. of animals. Also, an adhesive prepared from this substance by heating with water. Through general use the term is now synonymous with the term "adhesive."

Glue line - The layer of adhesive that attaches two substrates. Same as bond line.

Green strength - This refers to the relative cohesive strength an adhesive, glue, or mastic has in the wet state. Same as green grab or initial tack. See also tack.

Gum - Any of a class of colloidal substances, exuded by or prepared from plants, sticky when moist, composed of complex carbohydrates and organic acids, which are soluble or swell in water.

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H

Hap - Hazardous Air Pollutant

Hardener - A substance or mixture of substances added to an adhesive to promote or control the curing reaction by taking part in it. The term is also used to designate a substance added to control the degree of hardness of the cured fill. Same as curing agent. See also catalyst.

Hardwood - Wood from deciduous trees (i.e. oak, maple, cherry, etc.)

HMIS - Hazardous Materials Information System. A hazard rating system of the National Paint and Coating Association (NPCA).

Hot Melt Adhesive - An adhesive that is brought into a liquid state by heating and applying while it is hot.

Hygroscopic - Readily adsorbing moisture from the air.

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I

Inflammable - Capable of being easily set on fire and burning violently.

Inhibitor - A substance that slows down chemical reaction. Inhibitors are sometimes used in certain types of adhesives to prolong storage or working life. Same as retarder.

Interface - The common boundary surface between two substances.

IR Pyrometer - A device designed to measure surface temperature by Infrared emissions.

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J

Joint - A general term referring to the area of adherend -adhesive - adherend in the bonded assembly; the general area of contact for a bonded structure.

Joint, lap - A joint made by placing one substrate partly over another and bonding together the overlapped portions.

Joint, starved - A joint that has an insufficient amount of adhesive to produce a satisfactory bond.

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K

Kilo - Prefix meaning one thousand (K).

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L

Laminate (noun) - A product made by bonding together two or more layers of material or materials.

Laminate (verb) - To unite layers of material with adhesive.

Legging - The drawing of filaments or strings when adhesive-bonded substrates are separated.

Load - The material being heated.

Longitudinal Grain - Grain orientation in which wood fibers are parallel to the length of the tree.

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Bird Song Adhesives, Inc., 2012