Glossary of Inkjet Terms

Ablation

The erosion or wear of a surface from thermal or mechanical stress. In thermal inkjet printing (TIJ) the rapid and frequent collapse of heated microbubbles creates wear of the chamber and reduces the effective work-life.

Acuity

The sharpness of image, text, or graphics in printing. Generally, low acuity can be seen more prominently in images produced with lower-resolution printheads.

Addressability

The ability to control the placement of individual droplets. Sometimes expressed as dots per inch or centimeter.

Angstrom unit

A unit of length equal to one hundred-millionth of a centimeter, 10−10 meters, used mainly to express wavelengths, such as UV and LED curing lights.

Archival

While not quantifiable, the term describes the relative ability of the printed images to retain their color or blackness over time.

Array

Individual ink jets aligned or grouped.

Automatic symbology

Visible or invisible barcodes or other machine-readable images.

Agglomeration

Ink pigment particles join or cement together creating larger particles. The effect is lower ink dispersion and can also cause clogging of the printhead nozzle.

Aqueous Ink

An ink solution using water as the carrier. It is also known as water-based ink.

Arc lamp

An ultraviolet (UV) light source using an excited mercury vapor to create the wavelength.

Binary printhead

A drop-on-demand printhead where all drops ejected by the printhead are of the same volume.

Bubble Jet

Drop-on-demand (DOD) inkjet technology that rapidly boils the ink to create a bubble that is ejected as a drop. Also called Thermal Inkjet (TIJ).

Break-off

The point at which surface tension causes an ink droplet to pinch off from a continuous ink stream relative to the voltage phase of the inkjet printhead.

Bleed

Is caused when inkjet ink spreads or diffuses on or into other inks or the substrate. It is often considered a defect because it reduces image acuity. The term can also refer to eliminating air from the chamber of a continuous inkjet printer (CIJ) or from the ink delivery system of a piezo printhead inkjet printer.

Capping

Covering the inkjet printhead when idle to avoid damage, ink evaporation or unintended curing from a light source.

Carrier

The base solution of the ink into which dyes, pigments, and other additives are combined.

Catcher

The part of a continuous inkjet printer that captures unwanted droplets before reaching the printing surface. These intercepted droplets are generally recirculated into the ink reservoir.

Cavitation

The creation and collapse of bubbles from heating that raise the vapor saturation pressure within a continuous inkjet module resulting in erosion of printhead surfaces.

Chamber

The cavity area directly behind the orifice plate in an impulse printhead in Piezo technology. It is called a manifold in continuous inkjet systems.

Channel

The components of one unit of a printhead, which include the piezoelectric transducer, restrictor, associated chamber, and orifice plate.

CIJ

The acronym for continuous inkjet, which is one of two broad types of inkjet technology. The other being drop on demand (DOD).

Charge element

The electrodes in a CIJ printer that create an electrical field that controls the trajectory of the droplets to the substrate or the recirculation system.

CMYK

The letters refer to cyan, magenta, yellow and black inks used for producing process colors.

Coalescence

The recombining of satellite and main ink droplets in the air before reaching the printing surface.

Cockle

The wrinkling of paper from too much liquid is applied, usually when water-based ink applied to a small area.

Cogation

The build-up of ink particulates on the surface of a thermal inkjet chamber caused by the heating of the ink.

Color Gamut

The range of colors that can be produced using CMYK (four-color) printing.

Colorant

The dye or pigments used to produce the ink color.

CP/OP

The chamber plate or orifice plate.

cP

The measurement of viscosity used to determine a liquid’s ability to resist flow. The viscosity of ink can vary based on environmental and mechanical influences.

Crosstalk

The increase or decrease of ink droplet velocity in a channel caused by the firing of adjacent channels.

CPI

The nozzle density or channels per inch.

Curie temperature

The temperature point that piezoelectric inks lose their magnetism.

Curing

The process of solidifying ink using heat, light (UV or LED) or electron beam (EB) sources.

Decap time

The time that inkjet nozzles can be uncovered and idle before requiring wiping or purging.

Deflection Plate

The electrical component that charges continuous inkjet droplets causing them to be recirculated rather than striking the printing surface.

Degassing

Removing dissolved air in ink to avoid bubbles forming in the printheads that can cause nozzle failures.

Demand Printing

A process that can print any image at varying quantities limited only by its data system and its resolution limits.

Deprime

The failure of ink to be expelled because of air trapped in the chamber.

Dispersion

The distribution of ink components, such as pigments, throughout the solution.

Dithering

Also known as screening or halftoning, it is the representation of a share using a pattern of dots that appears to be solid.

DOD

Drop-on-Demand. It is the printhead technology that uses electromechanical valves to release ink onto the printing surface.

Dot

A measurement of the spread of a droplet of ink on a substrate before it cures or dries.

DPI

Dots Per Inch which is a measurement of addressability of an inkjet printer.

Drive waveform

The electrical signal applied to the print module actuator or heater to expel the ink from the chamber.

Droplet production rate

The maximum droplets of ink produced by an orifice, chamber or print system expressed in droplets per second.

Drop placement accuracy

The accuracy of drops landed on the printing surface, which is dependent on jet alignment, distance, and drop velocity.

Drop size/volume

The volume in picolitres (pL) of a drop from the printhead.

Drop velocity

The speed of an ink droplet ejected from the print nozzle.

Drying time

The time required for ink to dry to the touch after application to the substrate.

Duty cycle

The time a printing system is operating compared to idle time.

Dwell time

The time nozzles can be uncovered and idle before performance printhead is reduced.

Dye

A soluble ink colorant in the base solution.

Edge/end shooter

A DOD printhead with ink fired from nozzles on the edge of the printhead, perpendicular to the action of the heater or actuator.

Electron Beam (EB) Curing

Ink that is cured with high-energy electrons rather and no photoinitiators.

Face shooter

A printhead with the actuator diaphragm or heater parallel to the nozzle plate.

Fastness

The description of the resistance to degradation of printing by various environmental factors: water-fastness, wash-fastness, rub-fastness, and light-fastness.

Firing frequency

The number of drops ejected from a nozzle per second. Related: Drop Velocity, Drop Size.

Fixed array/Single-pass

An arrangement of printheads that cover the width of a substrate with the printing surface passing under the printheads. The printheads are stationary.

Feathering

The spread of ink often caused by the capillary action of the fibers of the substrate.

Firing

The process or event causing the ejection of the droplet.

Flocculation

The coagulation of particles in an ink solution, which can be reversed through shaking. Agglomeration, while similar, is irreversible.

Flush

A fluid used for cleaning inkjet printing systems or the process of cleaning a system.

Foaming

Air bubbles created from dissolved gas being released in ink when agitated.

Food grade

Ink that meets strict government regulations for printing directly on food packaging products.

Grayscale printhead

A DOD printhead technology that ejects different sized drops to improve print quality.

Heater

In a thermal inkjet printhead the mechanism that boils the ink, creating pressure that expels the ink from the nozzle.

Hot melt ink

Often these are wax-based Inks that are solid at room temperature and liquid when heat is applied. These inks don’t penetrate the substrate surface, making them less rub-fast.

Image quality

A subjective, non-quantifiable assessment of the printed image.

Impulse inkjet

Technology that relies on pressure to expel the ink from the nozzle. Piezo-based systems create pressure through a crystal that changes the pressure of the ink in the chamber. Thermal systems rapidly boil the ink to create bubbles.

Ink manifold

The control system that receives ink from the supply tank and distributes it to individual chambers or orifices.

Ink system

Delivers the ink to the printhead at the right temperature and pressure.

Interfacial tension

The fluid property relationship of the liquid to a solid surface. Also called the “wetting” property, it is the measure of the contact angle between the liquid and surface.

Interlaced, interdigitated, interlocked

The overlapping alignment of rows of orifices, often on a scanning printer that creates an image using multiple printing passes.

Jet straightness/deviation

The variance in an ejected ink drop perpendicular to the nozzle plate.

Kogation

Deposit of decomposed ink on heater components of thermal inkjet technology.

Jet

A stream of ink discharged from an orifice into free space.

Joule

The measurement of energy required to expel a droplet of ink.

Latency Time

The time nozzles can be uncovered and idle before printhead performance is reduced.

LED

The Light Emitting Diode emits a wavelength for curing inkjet ink.

Ligament

The tail of ink that follows the droplet after nozzle ejection.

Line speed

The rate a substrate passes under printheads.

LISS

Large Ink Supply System using bottles or vats.

Meniscus

The curvature of the ink at the printhead nozzle caused by the difference in pressure from the outside air and nozzle.

Magnetostriction

A magnetic mechanism that changes the shape of ferromagnetic fluids to expel the ink.

Multi-level CIJ

A continuous inkjet technology that delivers ink droplets to multiple positions on the substrate.

Monochrome

One color printing, often black and white.

Mottle

Uneven ink density or uneven color quality caused by inaccurate dot placement or varying dot density.

Multi-color

Printing with more than one highlight or spot color and black, but not process (CMYK) printing.

Nozzle

The hole from which the ink is ejected. It is also called an orifice.

Nozzle density

The spacing between orifices in a printhead.

Nozzle plate

The flat surface into which the nozzles are fabricated.

Optical density (OD)

The measure of how strongly ink absorbs light.

Orifice

See nozzle

Piezoelectric (PIJ)

Pigment

An ink colorant that is suspended and insoluble in the solution.

Phase change

See hot-melt ink

Prime

The initiating process of running ink through a print head to expel air from the chamber or manifold.

Pinning

Partially curing an ink with LED lamp.

Print distance

The distance from the bottom of the printhead to the substrate. It is also called the throw distance or print gap.

Printhead

The inkjet component containing a single or multiple channels that eject ink droplets.

Print to cure time

The time for a droplet to fully cure after striking the substrate.

Process color

See CMYK

Puddling

The liquid ink that accumulates on the exit side of the nozzle plate. In excess, the puddle can prevent ink from leaving the nozzles.

Purge

Clean or flush ink through the system to clean out debris or air.

PZT

Lead zirconium titanate is the crystal mainly used in PIJ technology.

Recirculating

The process of capturing and reusing ink in continuous inkjet systems.

Restrictor plate

Controls the flow of ink from the printhead manifold to the chambers.

Reynold’s number

A dimensionless number that plays a prominent role in understanding the patterns of a fluid’s behavior related to viscosity and inertia.

Satellite Component

An unwanted ink droplet produced behind the main drop during the break-off, which either merges with the main drop (fast satellite) or drifts away from the main drop (slow satellite) deposited on a different place on the printing surface.

Sensor resistor

An electronic component on each printhead to control the voltage to the transducers.

Shear mode

The method of causing a PIJ device to bend rather than changing length or volume.

Solvent

A liquid used as the carrier in solvent ink.

Stimulation

Applying energy to CIJ streams to produce a uniform ink stream.

Stitching

A defect caused by a non-aligned print head characterized by a dark line or gap from overlapping printing. Also, the joining of two print sections to create a single image.

Subpulsing

Stirring ink in the chamber with a low amplitude pulse without ejecting droplets.

Substrate

The printing surface. Read more about printing on different substrates.

Surface tension

Substrate force restraining an ink droplet into the minimum surface area possible.

Thermal Inkjet (TIJ)

Drop-on-demand (DOD) inkjet technology that rapidly boils the ink to create a bubble that is ejected as a drop. Also called Bubble Jet. (HP and Funai)

Throw distance

See print distance.

Transducer

Equipment that converts one type of energy into another. For piezo crystals, electrical energy is converted to mechanical energy in the form of motion that controls the ink flow.

TiO 2

Titanium dioxide often used for white pigment.

UV Cure

Ultraviolet light radiation causes a chemical reaction of polymerization to change the ink from a liquid to a solid.

Valve jet

A low-cost, low-resolution DOD technology using micro-electromechanical valves to spray large block images such as text or characters on cartons.

Viscosity

The physical property of liquids to resist flow or shear.

Volatile Organic Compound (VOC)

A carbon compound, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, that easily becomes vaporous or gaseous that participates in atmospheric photochemical reactions and are potentially hazardous. VOCs are often used as quick-dry solvents.

Wetting

The spreading of ink on a printing surface, determined by surface tension and surface energy.

Explore the various types of inks and technology at Kao Collins.

Inkjet printing glossary of terms