Glossary of Terms
Inkjet printing and ink formulation
June 24, 2001

Jerry Nevins

ARCHIVAL - The property of withstanding the effects of time. In the case of printed matter, the ability of the images to retain their color or blackness over long periods of time without fading. The use of stable pigments rather than dyes and 100% cotton pH buffered papers contribute to a print's archival qualities.

- Banding is a printing defect characterized by light or dark lines in an image in the direction of the printing. In the case of inkjet imaging it is caused by a jet or printhead that is not properly aligned, inoperative, or incorrectly indexed. The usual cause of banding is clogged or partially clogged nozzles in the printhead. Run cleaning cycles until banding clears up.

BUBBLE JET - A term used to describe the technology of using a thermistor to heat a water-based ink to form a bubble. This bubble causes the ink to shoot from the print head to the substrate. Found in Canon printers.

CAPILLARY FEED - A method used in some inkjet systems to transfer ink from the primary reservoir to the print head. This feeding mechanism uses the natural attraction of the ink for the tubing to keep a constant ink flow. Other systems use a pump to achieve the same results. Continuous flow systems offered for Epson desktop printers by MIS and Nomorecarts rely on capillary action of ink in the tubing.

COLORIMETER - An instrument used to measure the optical characteristics of a particular color and compare it to a set series of parameters. For additional information see L*a*b CPS - A unit of measurement for viscosity. It stands for centipoise. Most ink viscosities are stated in CPS. DPI - This term is an abbreviation for Dots Per Inch. It is a measure for the number of drops of ink an inkjet system can print in one linear inch. It is usually measured in both horizontal and vertical directions. (i.e. 300x300 dpi, 1200x1200 dpi)

DEFOAMER - An ingredient added to an ink to reduce the amount of air entrapment or foam that could be seen as the ink is made or placed in a cartridge or any other activity that could cause bubbles to form.

DISPERSION- A fluid containing a stable and uniform distribution of pigment particles.

DOD - This stands for Drop-On-Demand and relates to an ink jet printer that prints only as it is needed or demanded by its system.

DRAWDOWN - A test procedure comparison of an ink to a standard or OEM by "drawing down" the ink sample side by side with a standard sample on standard paper and comparing them visually.

DRY TIME - The time it takes for a non-porous ink to withstand incidental contact or rubbing without smearing.

DYE - One of the colorants used in all types of ink. They dissolve in the solvent base used for that particular ink (water, alcohol ... ), as opposed to pigment.

ENHANCED PIGMENT - A name given the inks made by us that incorporate both dye and pigment colorants. This is done to give the beneficial characteristics of both colorants to the ink.MIS Associates quadtone inks are said to be enhanced pigments

FEATHERING/WICKING - A term used to describe the tendencies of an ink to travel in uneven patterns into a given substrate. Excess feathering or wicking in a printed character is perceived by the user to be fuzzy and unclear.

FILTERING - A procedure to remove particles from an ink- These particles could plug one or more of the orifices in a print head.

FLOCCULATION - Undesirable coagulation or clumping of pigment particles in an ink formulation. Would quickly lead to nozzle clogging.

FREQUENCY - This term describes the speed at which a print head can print or shoot drops of ink at any given time. A typical frequency or drop rate for inkjet cartridges would be 2-5 Khz (2000-5000 drops/second).

HEXACHROME - The set of six process colors (cyan, magenta, yellow, orange, green and black) designed to widen significantly the color combinations possible when compared to the combinations available with the standard four process colors (cyan, magenta, yellow, black).

IMPULSE INK JET - A description given the piezo drop-on-demand inkjet print heads to delineate them from the valve jet drop-on-demand systems. It was meant to accentuate these newer technologies.

KOGATION - (Cogation) The term used to describe the deposit of dried ink on a thermistor in a print head. It was first thought that the impurities in the water caused this but newer studies found that it was, in fact, residual dye left from the continuous heating and cooling of the thermistor. These deposits can build and reduce the performance of the thermistor. Thermal heads are found on Hewlett Packard and Canon printers, among others.

L*a*b VALUES - A series of coordinates obtained from a Colorimeter that describes any color as a set of three values. The L coordinate designates a value from light to dark, the a coordinate designates a value from red to green and the b coordinate designates a value from blue to yellow. These three numbers position any color in the 3 axis area and allows a comparison to be made to match any particular color standard.

LIGHTFASTNESS - The durability of a print when exposed to light. When an ink is lightfast, it has fade resistance. It is generally thought that pigments have improved fade resistance over dyes. Archival prints strive to be lightfast.

MASSTONE - A large area of a substrate evenly covered with one color. It is usually obtained by printing an entire page with one color and is one of the methods used to determine a color match.

MENISCUS - This term describes the interface of a liquid to its container. It is caused by the degree of attraction a liquid has to the material of the container. The surface tension of the liquid is the major contributor to the shape and stability of this interface. It is one of the primary areas of research toward the functionality of an ink jet printer and relates to the ink presentation in the orifice.

NOZZLE - The area in some inkjet systems that directs the flow of ink immediately before the opening or orifice of the print head. It acts as a channel for the ink to use as it leaves the reservoir.

ORIFICE - The opening of the ink jet print head where ink shoots onto the substrate. Printheads contain a multiple of these openings and are arranged to give a set area of coverage as the print head moves along the print cycle. This is where the meniscus is located.

OPTICAL DENSITY - A measure of the blackness of a printed image. Optical density is also referred to as jetness.

PANTONE - A company that prints precise color match material used by the ink industry as standards for research and manufacturing.

PARTICULATES - Pieces of material or contaminants from various sources found in an ink. These can plug an orifice and cause lines in the print and is the reason for filtering the ink.

PENETRANT - An ingredient added to the ink that assists in the penetration or setting of the impression into the substrate. It assists giving the impression a smooth, even appearance.

pH - A measure of the acid or basic character of the ink. The pH values are in a range of 0-14 with a low pH being acidic and a high pH being basic. Some ingredients in certain inks need a set pH range to assist in their solubility.

PHOTOQUALITY - This term is used in the printer industry to describe the photographic type quality being addressed by some printers. Manufacturers are trying to achieve this quality in a number of ways including smaller dots, improved dpi, and coated substrates.

PIEZO - A shortened term for Piezoelectric Ceramic Crystal. This material has the ability to expand and contract with the application of electric current. This ability allows a piezo to be the engine in a very small pump. Since it has no moving parts, the durability of the material is extremely good. Found in Epson printers with 90% of the piezo market.

PIGMENT - A solid colorant used in various inks. Unlike dye, this material does not dissolve in the inks solvent but remains a particle. Because of this, it gives improved coverage over certain substrates and usually has improved fade resistance.

PRINT DISTANCE (GAP) - The distance between the orifice of an ink jet printer and the substrate itself This distance is important because as the inkjet drop travels, it can lose velocity and drift from its intended target.

RESERVOIR - The container or storage area for the ink in an inkjet system as is waiting to be used. It can vary greatly in size, content and construction.

REVERSE OSMOSIS - The process of forcing water through a semi-permeable membrane for the removal of particulates and other matter. It is one of the significant steps taken to purify water for use.

SATELLITE - A term used to describe a extraneous dot of ink that travels away from the primary drop as it is shot from an inkjet engine. They are called satellites because they travel around the primary drop of ink.

SOLVENT (Also Cosolvent)- The primary ingredient in an ink that is used to dissolve the dye. In inkjet cartridges, the solvent is water.

SOLUBILITY - The ability of a dye to be dissolved in a specific solvent. This ability varies greatly with the dye and solvent chosen.

STRIKE THROUGH - A term used to describe an ink that penetrates through a substrate. The effects can be seen by looking at the back of the substrate to visibly see any color on the other side. Some substrates are specifically designed to hold the maximum ink and keep it from going through to the other side.

SURFACE MODIFICATION - A proprietary technique utilized by Cabot in which specific chemical groups are attached to the surface of pigments through a covalent bond. The nature of these chemical groups and the precision with which they are attached allow for the high stability, reliability, ease of use, and print performance properties that Cabot's pigment dispersions are known for.

SURFACE TENSION - The attraction of a liquid for any material with which it has contact. A high surface tension means low attraction and a low surface tension means a high degree of attraction. Water has a high surface tension so it beads on wax paper. If you add soap to the water it reduces the surface tension and causes the water to penetrate the wax paper.

SURFACTANT - A material added to an ink to adjust the surface tension to the point needed. Usually, it lowers the surface tension. Surfynol 465 may be used.

TAILING - Each drop of ink printed out of an ink jet printer has a tail or portion of the drop that is traveling slower than the main body. As the drop travels farther from the print head, the tail gets longer. If the tail gets too long or if the substrate is traveling too fast, the drop does not hit in just one spot but is spread out along the path of travel.

THERMAL - See definition for BUBBLE JET THERMISTOR - A heating element located inside a thermal print head that heats the water-based ink very quickly thereby forming the bubble that ejects the ink out of the orifice. (see ORIFICE definition for drawing)

UV VISIBLE SPECTROPHOTOMETER - An analytical instrument used to measure the absorption of light by a colorant at certain wavelengths. The instrument emits light wavelengths from the Ultraviolet to the Visible ranges through a sample and measures how much is absorbed. This is a common and practical way to measure the quality of a dye and characterize its spectra.

VISCOSITY - A measure of the relative thickness of a liquid. Lower viscosities are like water while higher viscosities are like syrup. Viscosities are usually measured in CPS.

WATERFASTNESS - The resistance of an impression to dilution or removal by water. A waterfast ink has a reduced tendency to wick, feather or be washed away.


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