Glossary

Look up industry jargon and terminology

A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z

A

Abrasion Resistance: The ability of a surface to resist wearing due to contact with another surface moving with respect to it.
Absorptivity
(absorption coefficient):
Absorbance per unit thickness of a medium.
Acrylate: Acrylates are a family of polymers made from acrylate monomers. Acrylate monomers are esters which contain vinyl groups, that is, two carbon atoms double-bonded to each other, directly attached to the carbonyl carbon.
Acrylic:  A synthetic resin made from acrylic acid or a derivative thereof. Acrylics possess the property of transparency, as well as flame resistance.
Adhesion: The state in which two surfaces are held together by interfacial forces. These forces may be valence forces, interlocking action or both.
Aliphatic: Acyclic or cyclic, non-aromatic carbon compounds. Aliphatic compounds are opposite to aromatic compounds. Alphatic compounds lack the presence of Benzene rings.
Adhesion Promoter: A substance which is applied to a substrate to improve the adhesion of a coating to the substrate.
Adhesive: A substance capable of holding materials together by surface attachment. Adhesive is the general term that includes cement, glue, mucilage, and paste (among others).
Anaerobic Adhesives: Fast-setting adhesives that cure in the absence of oxygen. They need to be packaged in oxygen-penetrating containers and usually filled only partially to allow plenty of oxygen-rich headroom in the container. These adhesives cure when the oxygen is cut off by the bond line, so close fitting surfaces are desirable. Commonly used in thread lockers and machine fasteners.
Aromatic: Containing one or more six-carbon rings characteristic of the benzene series and related organic groups.
ASTM: American Society for Testing Materials.

B

Benzoin Ether: A group of chemical materials, most of which are sensitive to light and readily form free radicals. Chemical structure is ArCOCHORAr. Some of these are useful photoinitiators.
Bond Strength:  The strength of the union between materials.
Brookfield Viscosity: Simple viscosity value obtained with a Brookfield viscometer. See viscosity for more information.

C

Catalyst: Any material which aids completion of a chemical reaction without itself becoming part of the product.
Cationic Cure: Occurs when an energized molecule reacts with cationically sensitive monomers to initiate polymerization.
Celsius: A scale of temperature which features 0° and 100° as the freezing and boiling point of water respectively. To convert centigrade to Fahrenheit multiply by 1.8 and add 32. (100° x 1.8) + 32 = 212°F. View our Fahrenheit and Centigrade conversion chart.
Centipose: 1/100th of a poise; (dyne-sec/cm2); a viscosity measurement unit.
Chemical Resistance: Ability of solid materials to resist damage by chemical reactivity or solvent action.
Coating:

A covering that is applied to the surface of an object. Coatings are often applied to improve surface properties of the substrate, such as appearance, adhesion, wetability, corrosion resistance, wear resistance, and scratch resistance.

Coefficient of Friction: The measure of the relative difficulty with which the surface of one material will slide over an adjacent surface of itself or another material.
Coefficient of Thermal Expansion: The measure of the change in length of a material when subjected to specified temperatures.
Compatibility: The ability of ink, film, substrate and/or solvents to function together in an acceptable manner. Manufacturers of inks, plastics and other printing materials usually recommend specific ink/solvent/substrate systems that are compatible. Essential to the ultimate performance of the system. Can also include compatibility with the screen stencil.
Conformal Coating: A thin non-conducting coating that is either plastic or inorganic and is applied to a circuit for environmental and mechanical protection.
Crosslinking Agent: A reactive chemical material which will form bonds between other molecules in a formula.
Cure: To change the physical properties of an oligomer by causing a material reaction. This reaction can be initiated by a chemical process or energy.
Cure Time: The time/temperature combination required to bring organic decoration to the desired level of hardness, caustic and chemical resistance, etc.
Curing Agent: A UV-curing reactor that houses a UV energy emitter used for the polymerization of ultraviolet curable inks, coating,s and adhesives.

D

Dark Reaction: Reactions which take place in closed containers of radiation curable formulations, usually premature polymerization.
Degree of Cure: In UV-curable coatings, it is generally inversely related to the level of free monomer.
Dendrimers: Star or ball polymers that are built up layer by layer.
Dendritic: Hyper-branched polymer networks that can be polymerized to themselves and to other monomers or oligomers. They mimic the properties if dendrimer oligomers.
Density: The ratio of a substance's mass to its volume at a given temperature and pressure. Example: water at 25°C, 1 atmosphere of pressure = 1.0 gr/cm3 = 8.35 lb. per gallon.
Diluent: A reactive or non-reactive additive whose primary function is to lower the viscosity and extend the material to which it was added.
Discoloration: Any change from an initial color possessed by a material, either due to environmental or internal conditions.
Dispersing Agent: A material added to a suspended medium to aid in the separation of the individual, extremely fine particles such as pigments or colloids.
Dose: Energy absorbed per unit mass. Usually Megarads = one million rads. One megarad equals 108 ergs/g., 2.30 calories/g, 4.3 BTU’s/lb., 10 wattseconds/g or 4.54 KW seconds/lb.
Double Bond: A type of chemical bond wherein two pairs of electrons are shared between two atoms.
Durometer Hardness: See Shore Hardness.
Dynamic Mechanical Analysis (DMA): Also know as Dynamic Mechanical Spectroscopy. A  technique used for studying the viscoelastic behavior of polymers. A sinusoidal stress is applied and the strain in the material is measured, allowing one to determine the complex modulus. The temperature of the sample or the frequency of the stress are often varied, leading to variations in the complex modulus; this approach can be used to locate the glass transition temperature of the material.

E

EB-Radiation Curing: Form of curing where electron beams are used to induce a radical reaction and thereby facilitate polymerization in a material. Energy range of 90-250 KeV.
Elasticity: That property of materials by virtue of which they tend to recover their original size and shape after deformation.
Elastic Modulus: The mathematical description of an object or substance's tendency to be deformed elastically when a force is applied to it.
Elastomer: A material that, at room temperature, can be stretched repeatedly to at least twice its original length. When the stress is removed, the material immediately returns to its approximate original length.
Elongation (%): The maximum distance a material will stretch in a lengthwise direction before breaking, expressed as a percent of the original (unstretched) length.
Embrittlement: The loss of plasticity resulting in brittleness.
Emission spectra: Radiation from an atom or atoms in an excited state, usually displayed as radiant power vs wavelength. Emission spectra are unique to each atom or molecule. The spectra may be observed as narrow line emission (as in atomic emission spectra), or as quasi-continuous emission (as in molecular emission spectra). A mercury plasma emits both line spectra and continuum simultaneously.
Encapsulant: The material used to cover COB devices to provide mechanical protection and to ensure reliability.
Energy density: Radiant energy arriving at a surface per unit area, usually expressed in joules or millijoules per square centimeter (J/cm2 or mJ/cm2). It is the time-integral of irradiance. Same as exposure. For a parallel and perpendicularly incident beam, not scattered or reflected, energy density and fluence become identical. Compare fluence. [Not equivalent to dose].
Epoxy Resin:

A thermosetting polymer formed from reaction of an epoxide "resin" with polyamine "hardener".

Exotherm: The liberation of heat energy during a chemical reaction. Exotherm is increased in large masses.
Exposure: Effective radiant energy density at a surface; the time-integral of irradiance within a specified bandwidth, expressed in J/cm2 or mJ/cm2. The time-integral of fluence rate, in J/m2 or J/cm2. Also radiant exposure. In solar UV exposure applications, larger units may be used – J/m2 or even MJ/m2. Compare fluence. [Not equivalent to dose]. The definition varies in radiation chemistry in clinical chemistry.
Extractables: Any material which can be removed from a cured film by solvents, usually measured as a weight difference.

F

Fatigue: Condition of stress in a material resulting from repeated flexing or impact.
Filler: A substance, often inert, added to a system to improve properties and/or decrease cost.
Film Thickness: The distance from one face surface to the opposite face surface of a film material usually measured in mils or microns.
Flame Retaardant: A material which, when added to the formulation, decreases its flammability.
Flash Point: The temperature at which the material gives off flammable vapor in sufficient quantity to ignite momentarily on the application of a flame under specified conditions.
Flow Agent: An additive used to disturb the surface tension and increase the ink flow, when bubbles or orange peel occur.
Free Radical: A reactive material which initiates polymerization in UV curable formulations, generally by the loss of an electron.

G

Gel: A polymeric or monomeric material that undergoes an irreversible change due to cure. A gel will not dissolve in a solvent, it will only swell.
Gel Point : The stage at which gelatin begins.
Glass Transition Temperature (Tg): Approximate midpoint of the temperature range over which a material undergoes a phase change from brittle to rubbery or vice versa.
Gloss: The property of a surface which causes it to reflect light.

H

Hardness: The property of a material which causes it to resist indentation and scratching.
Haze: That percentage of transmitted light which in passing through the specimen deviates from the incident beam by forward scattering.
HDDA: 1,6-Hexanediol Diacrylate
Humidity (Absolute): The amount of moisture present in the atmosphere expressed in grams per cubic meter.
Humidity (Relative): The ratio of the amount of moisture contained in the atmosphere to the amount of moisture that can be carried in the atmosphere at a given temperature. Relative humidity is expressed in percent, e.g., 75% R.H. at a given temperature means that the air is 75% saturated with moisture.
Hydrolysis: Decomposition of a chemical compound by reaction with water, such as the dissociation of a dissolved salt or the catalytic conversion of starch to glucose.
Hydrolytic Stability: Tthe measure of a material’s resistance to hydrolysis.

I

IBOA: Abbreviation for isobornyl acrylate.
Immiscible: Incompatibility by mixing; e.g., oil and water.
Impact: The energy absorbed by a specimen when subjected to a falling object.
Inhibitor: A substance, sometimes added to a coating material to extend pot life, which retards a chemical or catalytic reaction.
Insoluable: Describes a condition in which a solute will not dissolve in a particular solution.
Intensity: Measure of light energy over the unit of surface area (usually surface at the specified working distance from the bottom of reflector housing) in W/cm2 or mW/cm2. For the UV portion of light, this measure is often called in literature “irradiance”, i.e. radiant energy arriving at a point on a surface per unit area. View our intensity conversion table.
Intermediate: Any chemical substance which either is consumed in whole or in part in chemical reaction(s) used for the manufacture of other chemical substance(s) or mixture(s), or is intentionally present for the purpose of altering the rate of such chemical reaction(s).
Irradiation: Exposure to ultraviolet light or other high energy.
Irritant: A chemical substance or mixture (not a corrosive) which on immediate, prolonged or repeated contact with normal living tissues induces a local inflammatory response in the skin, eyes, or mucous membrane.

J

Joule (millijoule): A unit of work or energy (a newton-meter). The time-integral of power. Abbreviated J or mJ. (Although derived from a proper name, the term joule is not capitalized, while its abbreviation is capitalized).

K

KeV: Kiloelectron Volt. A unit of energy used in EB Curing.

L

Laminant: Adhesive used for combining and bonding films, foils, plastics, papers, or other material in sheet or web form.
Lamp: The source of UV light used in exposing photosensitive materials.
Light: Radiant energy in the visible range of the electromagnetic spectrum.

M

Mar Resistance: The ability of the surface of a material to withstand mechanical forces.
Mechanical Properties: Of a plastic material, its elasticity.
MEK Double Rub Test: A standard test evaluating solvent resistance. The surface of a baked film is rubbed with a cheese cloth soaked with MEK until failure or breakthrough of the film occurs. The type of cheesecloth, the stroke distance, the stroke rate, and approximate applied pressure of the rub are specified. The rubs are counted as a double rub (one rub forward and one rub backward constitutes a double rub).  
Methacrylate: An ester of methacrylic acid, having the general formula C4H3O2R, where R is an organic radical. Methacrylates are commonly used in the manufacture of plastics.
Mercury Lamp: Lamp in which light is generated through presence of mercury vapor. Most UV lamps are mercury vapor lamps.
Migration:

1) The movement of one or more components of adhesive to either a substrate or a face material, or the movement of one or more of the components of either or both of the face material and the substrate into the adhesive.

2) The movement of one or more components of an ink film into a succeeding application of ink. Usually a discoloration caused by a dye type pigment in the preceding coat or print.

Modulus of Elasticity: The mathematical description of an object or substance's tendency to be deformed elastically when a force is applied to it.
Moisture Resistance: Having some resistance to high humidity.
Monomer: A molecule of relative low molecular weight and simple structure capable of combining with itself or other similar molecules through reactive sites to form a polymer.

N

Nanometer: Unit of length. Abbreviated nm Equals 10-9 meter, = 10-3 micron, = 10 A (angstrom). Commonly used unit to define wavelength of light, particularly in the UV and visible ranges of the electromagnetic spectrum. An older equivalent term, millimicron, is rarely used today.
Newtonian Liquid: Fluids which have an absolute viscosity at a given temperature regardless of shear.
Non-Newtonian Liquid: Fluids which have a varying viscosity at a given temperature based on shear.

O

Oil Resistance: The ability of a material to withstand contact with an oil without deterioration of physical properties, or geometric change.
Oligomer: An oligomer is a molecule that consists of a few monomer units. Oligomers give a cured coating, ink, adhesive, etc. it's physical performance characteristics like flexibility, abrasion resistance, chemical resistance, hardness, or adhesion.
Omnirad™ 481: Common photoignitator for oligomers. IGM resins trademark. Also know as Iragure 184.
Opaque: A material that no light can be transmitted through.
Oxygen Inhibition: The effect of oxygen to terminate or slow a polymerization reaction by deactivating radicals.

P

Peak Tan Delta: Occurs at the highest temperature and measures the midpoint between the glassy and rubbery states of a polymer.
Pencil Hardness: The resistance of a coating as determined by the grade of the hardest pencil that does not mark the coating when pressed firmly against it at a 45° angle. View our pencil hardness table.
Percent Elongation: The increase in length produced by a tensile load, expressed as a percentage of the gauge length.
Photochemistry: The study of chemical actions influenced By the action of light.
Photoiniator: A substance which absorbs light and is directly involved in the production of initiator radicals for polymerization (as in UV curing).
Photopolymer: A composition which will either crosslink or depolymerize on exposure to light, forming a physical differentiation between the exposed and unexposed portion.
Platimum-Cobalt
Color Scale
(Pt-Co):
Also known as the Alpha-Hazen Scale. A standard test method for color of clear liquids. The Pt-Co Color Scale is specific to the color yellow and is based on dilutions of a 500 ppm platinum cobalt solution.
P.S.I.: Pounds per square inch; a unit of measure of pressure.
Polymer: A macromolecule consisting of an indefinite number of monomer units. The molecular weights may range from about 20,000 into the millions.
Polymerization: A chemical reaction in which the molecules of a monomer are linked together to form large molecules whose molecular weight is a multiple of that of the original substance. A polymer is a material formed by polymerization.
Polymerize: To chemically unite two or more polymers or monomers of the same kind to form a molecule with a higher molecular weight.
Pot Life: A term indicating the length of time during storage in a specific container under normal storage conditions, that chemical composition will not lose usefulness through deterioration in the original container. Also called “Working Life”.

Q

Qualitative: A description of the quality of a material.
Quantitative: A description of the amount of a material.

R

Radiation: Radiation as generally applied to coatings and printing inks comprises three energy groupings: high velocity electrons (electron beam and scanning linear cathode), ultraviolet and infrared energy.
REACH: Acronym for Registrations, Evaluation, Authorization, and restriction of Chemical substances. Read more abour REACH.
Reactive Diluent: A chemical which serves two purposes in a formulation; thinning or viscosity reduction, and providing reactivity with other ingredients for curing or polymerization.
Refractive Index: Also called the index of refraction. The measure of the bending of a ray of light when passing from one medium into another
Resin: An organic material that has an indefinite and often high-molecular weight. Resins tend to flow when subjected to stress, usually have a softening or melting range, and usually fracture conchoidally.
Rheology: The study of the change in the form and flow of matter, including elasticity, viscosity, and plasticity.
RoHS: Acronym for Restriction of Hazardous Substances. Read more abour RoHS.

S

Shear: The stress which tends to make one part of a body slide over the adjacent part.
Shear Strength: The sliding force required to break a bond, divided by its cross-sectional area.
Shelf Life: The amount of time a material may be stored under specified conditions with no significant changes in properties.
Shore A Hardness: The reading of a material's hardness on a durometer, the scale of which is 0-100, used on elastomers and other flexible materials. Consists of a pin point depression into the material, the material being at least 100 mils thick. A Shore A reading of 80 equal a Shore D reading of 30. View our comparison chart.
Shore D Hardness: The reading of a material's hardness on a durometer, the scale of which is 0-100, used on rigid and semi-rigid materials. Consists of a pin point depression into the material. Both the Shore A and Shore D instruments are made by the Shore Instrument Manufacturing Company, Inc. Jamaica, NY. View our comparison chart.
Shrinkage: The decrease in volume, or contraction, of a material by the escape of any volatile substance, or by a chemical or physical change in the material.
Solvent: A substance capable of dissolving another substance to form a uniform, dispersed mixture at the molecular or ionic level.
Stabilizers: Additives to coating, ink or adhesive formulations which help extend shelf life, resistance to heat or other degradation.
Storage Life: The period of time during which a packaged adhesive or curing agent can be stored under specific temperature conditions and remain stable for use. Sometimes called shelf life.
Stress: An applied force or pressure, as tension or shear, exerted on a body which produces a resultant strain on the material. The ability of material to withstand a stress depends on the strength of its cohesive force or molecular resistance.
Substrate: A material upon the surface of which an adhesive is spread for any purpose, such as bonding or coating.
Surface Resistivity: The resistance to a current flow along the surface of an insulator material. Measure in ohms-cm.
Surface Tension: The property of a liquid which causes the surface to pull into the smallest area for a maximum volume, hence, drops are spherical. The fact that water drops on a wax surface do not spread out due to surface tension. If a wetting agent were to be added to the water the round droplet would spread out into a film because of the lowered surface tension.

T

Tackifiers: Chemical compounds used in formulating adhesives to increase the tack.
Tensile Strength: The pulling force necessary to break a bond, divided by its cross-sectional area. Tensile strength is the resistance of a material to stretching without rupture. It’s expressed in pounds per square inch.
Thermal Conductivity: A measure of how rapidly heat is conducted through a material.
Thermal Shock Resistance: The ability of a cured system to resist cracking or crazing under conditions of rapid and continuous thermal change. The 1/4 inch Olyphant Washer test is cycled over a temperature range of -55°C to +125°C, this temperature is normally used as the test condition unless otherwise stated.
Through Cure: The curing of the bulk of a material down to and including the material/substance interface as opposed to a surface cure where only the material/air interface is cured.
TMPTA: Abbreviation for Trimethylolpropane Triacrylate, a trifunctional monomer.
Toughness: The stiffness, rigidity or resilience of a material.
TPGDA: Abbreviation for Tripropyleneglycol Diacrylate..
Transclucent: A term indicating the property of a substrate or other material to permit passage of some light rays in a diffused manner so as not to clearly establish the design or object from which the rays are reflected.

U

Ultraviolet (UV): The invisible region of the spectrum just beyond the violet end of the visible region. Wavelength ranges in general from 1.0 to 400 nm. Dymax bulbs (burners) do not radiate energy in deep Ultraviolet; there are very minute amounts below 220 nm and practically nothing can be sensed below 200 nm. This is due to the use of an ozone blocking quartz bulb envelope (See Ozone).
Ultraviolet Curing: Polymerization effected by the presence of ultraviolet rays.
Unsaturation: In UV-curable formulation, a double bond in a molecule which reacts to free radicals.
UV: Ultraviolet. Radiant energy in the 100 nm to 450 nm range. 100 nm to 200 nm is generally called vacuum UV (VUV), because it does not transmit in air. There is no precisely defined boundary between UV and visible light, and may be considered about 400-450 nm.

V

Viscosity: How well a fluid flows. It’s usually measured in Centipoise (cps). The lower the number, the thinner or more pourable the liquid. Water has a viscosity of 1 cP, corn syrup has a viscosity of 3,500 cP, and ketchup has a viscosity of 50,000 cP. View our comparison
chart
.
Volatiles: Solid or liquid materials which pass into the vapor state at a given temperature.

W

Water Miscible: Solvents or other liquids which can be stirred into and blended with water.
Wave Length: A measuring unit to determine hue, color, or position in the spectrum.
Weatherability: Capability of withstanding the weathering process

X

Y

Yield Strength: The load in pounds per square inch (psi) where the material under test begins to change dimensions and will not completely recover when the load is removed. Yield strength will normally be lower than ultimate strength.

Z