Definitions of Common Terminology used in this Website

medium: in digital printing, object onto which >colorant gets applied and which carries the final image; can be made up of various layers, including the >substrate and coatings, and can be >laminated after the printing process.

substrate: the single or multi-layered base material of the >medium, which can have a very simple or complex structure and is a carrier for the coating, if present

Glossary

Note: Definitions marked with * are quoted from Websters New Encyclopedic Dictionary, New York, 1994

absorption: the sucking up or taking up or in by one substance of another, in the case of >colorants: the taking up of energy in form of light

acuity: sharpness

adsorption: the adhesion in an extremely thin layer of molecules (as of gases, solutes, or liquids) to the surfaces of solid bodies or liquids with which they are in contact*

agglomerate: to cluster

aggregate: to cluster in a dense mass

alumina: aluminium dioxide (AlO2)

analog: data consisting of or systems employing continuously variable signals or data, as opposed to discreet steps or levels of >digital data

anion: negatively charged ion; >cation

apparent resolution: resolution of a >hardcopy as it appears to the naked eye of the observer

archival: a term that has been used extensively in conservation literature, but that lacks an internationally accepted definition. general understanding: with characteristics of long term stability (as in: archival quality)

auxochrome: functional group that can be either >organic or salt-forming and is attached to a molecule to modify and/or intensify the color of that substance

banding: in this context, horizontal, parallel lines in an ink jet print caused by a falsely aligned or defective >printhead

binary: relating to, being, or belonging to a system of numbers having two as its base*

bit: shortened form of the term >binary digit, the smallest unit of information that can be stored in a computer

bleed: to wick; >feather

brightness resolution: resolution relating to the number of tonal values in a >digital image

buffer: a substance capable of neutralizing acids, incorporated into many museum boards and >archival paper products

calender: to press paper between rollers in order to smooth its surface

carcinogen: a substance or agent producing or inciting cancer*

cation: positively charged ion; > anion

cellulose: a complex carbohydrate constituting the chief part of the cell walls of plants, yielding many fibrous products, and being commonly obtained from vegetable matter (as wood or cotton) as a white fibrous substance [...]*, used on a large scale for papermaking

chain scission: >scission of a polymer chain

chroma: color saturation, degree of color purity

chromophore: a specific arrangement of atoms leading to >absorption of >photons at specific wavelengths within the >spectrum of a light source

CIE L*a*b*: three-dimensional color definition model with the parameters L*: lightness, a*: range from red to green, b*: range from blue to yellow

CIE Yxy: three-dimensional color definition model representing all colors visible to the average human eye with the parameters Y: lightness, x: amount of red, y: amount of green. usually representation is two-dimensional, excluding lightness Y

cockling: occurs as >cellulose fibers of a paper swell and shift due to >absorption of moisture, resulting in an uneven, wavy surface that often remains even after the paper has lost the excess moisture

colloid: a very finely divided substance that is scattered thoughout another substance, also: a mixture consisting of such a substance together with the substance in which it is scattered*

colorant: a substance, usually a >dye or a >pigment, with the ability to absorb a certain range of wavelengths from visible light, thus reflecting only the non>absorbed wavelengths, which is perceived as color

color depth: >brightness resolution of a digital image, measured in number of >bits / pixel

colorimetry: measurement and determination of colors

conjugation: in >organic chemistry, the presence of double and triple bonds in a molecule

continuous ink jet: an ink jet system in which pressure pulses are generated directly in the >printhead to eject a continuous stream of drops of ink which are consequently seperated into printing and non-printing drops by electrostatic deflection

continuous tone: a color or >monochrome image format or printing process capable of illustrating a gradual and virtually smooth scale of tonal changes

contone: abbreviation for continuous tone

co-polymer: combination of two or more different types of polymer in one molecule

cross-linking: bonds between two or more polymers

curing: to prepare by or undergo chemical or physical processing for keeping or use* (e.g. curing an adhesive with UV-radiation)

digital: data consisting of or systems employing discreet steps or levels, as opposed to continuously variable analog data

disperse: to distribute more or less evenly throughout a medium*

dissolve: to break up a substance into its component parts by uniformly mixing it into a liquid medium

dots per inch (dpi): measurement of output device resolution

drop-on-demand (DOD) / impulse: an ink jet system in which pressure pulses are generated directly in the >printhead by piezo crystals or heated resistors to eject drops of ink only when they are needed to print a dot

dye: a >colorant consisting of single molecules that are able to >absorb certain parts of the >spectrum of visible light and reflect others

excited state: in photochemistry, the state of a molecule after it >absorbs energy

extinction coefficient: also termed absorption coefficient, describes the amount of light of one wavelength absorbed by a molecule

feather: to wick; >bleed

gamut: the limited range of colors provided by a specific >input or >output device, or by a set of >colorants

ground state: in photochemistry, the state of a molecule before it >absorbs any energy

halftone: a method of simulating >continuous tone in >binary printing utilizing overlapping black or color process dots of varying size or position

hardcopy: >digital print on a >substrate; >softcopy

hue: color of an object as perceived by the eye

hydrolysis: a chemical process of decomposition involving splitting of a bond and addition of the elements of water*

impact printing: process of applying >ink to a >substrate utilizing physical contact between some part of the printing device and the substrate, (e.g. >offset, lithography, and flexography); >non-impact printing

ink: substance in ink jet printing (liquid or solid) which gets sprayed onto the >medium; made up of a >colorant, a >solvent, or >vehicle, and various additives

input: information fed into a >digital system

inorganic: in the context of chemistry, refers to substances that do not contain carbon atoms; >organic

ion: an atom or group of atoms that carries a positive or a negative charge as a result of having lost or gained one or more electrons; >anionic; >cationic

kogation: unique to thermal ink jet, caused by thermal de-composition of organic matter and the deposition of those products on the heat element of a thermal >printhead, thereby rendering it useless due to insulation of the heat element

Lab: abbreviation for >CIE L*a*b*

lake: a class of >pigments composed of a soluble dye >adsorbed on or combined with an >inorganic substance such as a metal

laminate: a clear coating of a variety of possible substances, usually plastic, that is applied to one or both sides of a >medium after printing for reasons of protection

lightfast: resistant to the destructive action of light

lignin: >polymer that occurs in the woody cell walls of plants and in the cementing material between them which is easily oxidized to form yellow-brown compounds and acidic products

lines per inch (lpi): measurement of output device resolution

medium: in digital printing, object onto which >colorant gets applied and which carries the final image; can be made up of various layers, including the >substrate and coatings, and can be >laminated after the printing process.

micelle: an >aggregation of molecules that constitutes a >colloidal particle

micron (µm): micrometer, unit of length equal to 10-6 meters

mil: unit of length equal to 10-3 of an inch (0.0254 mm)

molecular weight: weight of one mole (= 6 x 1023 molecules) of a substance in grams

monochrome: single colored

mordant: a chemical that fixes a >dye in or on a substance by combining with the dye to form an insoluble compound*

nanometer (nm): unit of length equal to 10-9 millimeter

non-impact printing: process of applying >ink to a >substrate without utilizing physical contact between some part of the printing device and the substrate, (e.g. ink jet); >impact printing

non-polar: >polar

nozzle: in ink jet printing, the orifice in the >printhead from which >ink droplets are ejected

offset: >analog ink-based printing process, in which ink adhering to a metal plate is transferred (offset) to a blanket cylinder before being applied to the >substrate

opaque: not transmitting light; >transparent

optical density (OD): >print density

organic: in the context of chemistry, refers to substances that contain carbon atoms; >inorganic

output: information fed out of a >digital system in the form of data or >hardcopy

oxidation-reduction: a chemical reaction in which one or more electrons are transferred from one atom or molecule to another*

pH: unit of measurement indicating the acidity or alkalinity of a substance on a scale of 0-14. pH<7 is acid, pH>7 is alkaline, pH=7 is neutral

phase change: an ink jet system in which pressure pulses in the >printhead eject drops of >ink that is in a heated, molten state, and which solidifies when it hits the >substrate

photo-catalysis: the chemical mechanism behind different fading characteristics depending on whether a >dye is alone or makes up a composite color

photon: a quantum (= subdivision of energy) of radiant visible energy

picoliter (pL): unit of volume equal to 10-12 liter

pigment: >colorant consisting of a natural crystalline molecules or an >agglomerate of synthetic >dye molecules

pixel: in the context of ink jet printing, the smallest image forming printed dot on the >medium

plasticiser: a chemical added to substances to impart flexibility, workability, or stretchability

polar: molecule having a dipole or substance characterized by molecules having dipoles, determines solubility characteristics; >non-polar

polyethylene (PE): plastic consisting of >polimerized ethylene

polymer: a chemical compound or mixture of compounds that is formed by polymerization and consists essentially of repeating structural units*

porosity: state of being able to absorb liquids due to pores

print density: or optical density (OD), of an ink jet >hardcopy is the visually perceivable and densitometrically measurable >absorbtion of light on the surface of a hardcopy due to the presence of a >colorant. OD only measures the surface density of a dry hardcopy, not the density of the total amount of >ink that was sprayed onto the >medium.

printhead: part of a >digital printer that is directly responsible for applying >ink to a >medium

print resolution: the >resolution of a >digital print

print-through: >show-through

proof: a test print used for final color correction in the printing industry

rag: in the context of paper manufacturing, cotton rags are a source for high quality >cellulose fibers

RC paper: >resin coated paper

receptor coating: layer adhered to the surface of the >substrate that has the function of receiving and binding >ink that arrives from the >printhead nozzle

recto: front side of an object; >verso

reduction: >oxidation-reduction

refractive index: measurement of the bending (refraction) of light entering a >translucent or >transparent substance

relative humidity (RH): the ratio of the amount of water vapor actually present in the air to the greatest amount possible at the same temperature*

resin: natural >organic substances that are formed especially in plant secretions and are used in varnishes, printing >inks, and >sizing; in this context, any of a large class of synthetic products that have some of the physical properties of natural resins but are different chemically and are used chiefly as plastics*

resin coated paper: or RC paper, term used for photographic paper used in most color and some black and white printing applications, which has a polyethylene coating on each side

resolution: in the >digital context, the capability of making up a larger image out of many small and discrete entities such as pixels; a measure of the greatest amount of detail or sharpness that can be seen in an image

resonance: in photochemistry, the capability of electron vibration in a >conjugated molecule

rosin: a >translucent, amber-colored, brittle, natural >resin that is obtained from pine trees and used in paper >sizing

scission: splitting, or division of a substance or an object; >chain scission

shellac: a purified form of the >resin lac, which is secreted by an insect and which is used for varnishing

show-through: occurs when >ink penetrates the paper >substrate and is visible from the back; also termed print-through

silica: silicon dioxide (SiO2)

sizing: a gluey substance such as a >resin, gelatin, or starch used for finishing, modifying, and filling the pores in a surface such as that of paper

softcopy: view of a file on a monitor screen; >hardcopy

solvent: a usually liquid substance capable of >dissolving or >dispersing one or more other substances*

spectrum: in this context, the full range of visible wavelengths of light energy radiation

substrate: the single or multi-layered base material of the >medium, which can have a very simple or complex structure and is a carrier for the coating, if present

surfactant: substances that enable the >dispersion or >solution of >non-polar molecules in >polar liquids or vice versa

tinctoral strength: measurement of the brilliancy of a >colorant

translucent: allowing light to pass through but >opaque instead of clear

transparent: allowing light to pass through but clear instead of >opaque

vehicle: in this context, a fluid or solid substance, depending on its physical state and on its desired function, that serves to either >dissolve or >disperse another substance or a range of substances and make them usable in a certain environment

verso: reverse side of an object; >recto

viscosity: the tendency of a liquid to flow slowly or quickly resulting from the friction of its molecules

waterfast: resistant to the destructive action of water

wettability: the ease by which a >pigment can be wet by an >ink >vehicle or a >substrate by a liquid

wick: to draw moisture by capillary action; in the context of ink jet printing: the tendency of an >ink to spread along paper fibers resulting in a loss of dot edge sharpness and overall image quality