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Glossary

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HAIRLINE REGISTER
Multi color printing on which misregister allowable is 1/ 2 row of dots; also the joining or butting of two or more colors, with no color overlap. See register and commercial register.

HALFTONES
An illustration printed as dots of varying size to imitate the continuous tonal gradation of a photograph. (screened illustrations). The process in printing to impart tonal value to a printed piece with a single color of ink, created by separating the different tonal value areas into dots of varying size. This can create a full range of from 5 to 95% ink coverage of the paper area to be printed.
The term "halftone" is used to signify any printed area that has been printed with small dots, to create a tonal effect, but technically, a "halftone" is a printed area where half or 50% of the area is covered by any number of, or sized dots of ink.

HANDMADE PAPER
Paper made by hand using a mould (a frame covered with a flat, rigid screen or flexible screen). In both cases the mould is covered by a flat frame called a deckle, to contain the run-off of wet pulp, dipped into a vat of wet pulp, shaken to distribute the fibers evenly and drained of its excess water. The wet mat of fibers remaining in the newly formed sheet is then dried against blankets & may be hot pressed, cold pressed, or air dried.

HARD BOUND
See case bound.

HARD COVER
In book publishing, a term used to describe a book that has been encased with heavy chip board that is covered with vinyl, leather, paper, or fabric.

HARD SIZED
Refers to a paper which has been heavily sized, to resist moisture penetration; opposite of slack sized.

HARD-SIZED PAPER
Paper treated with considerable size to resist water and ink penetration.

HARD SPOT
See ridge.

HARDWOOD
Wood obtained from a class of trees known as Angiosperms, such as birch, maple, oak, gum, eucalyptus, and poplar. These trees are characterized by broad leaves and are usually deciduous in the temperature zones. Source of "shorter" cellulose fibers for paper making, as extracted from deciduous or leaf bearing trees.

HARDWOOD PULP
Pulp obtained from deciduous trees such as Oak, Maple, Birch, Popular, etc. These fibers are shorter and bulkier than softwood fibers. Book papers have a predominance of hardwood fiber.

HEADBOX
The first section of the paper machine, where the furnish is mixed to provide a uniform suspension to the slice for the formation of a web of paper on the wire.

HEAT-SET INKS
Inks that use as their drying mechanisms, primarily (1) the evaporation of solvents and (2) solidification, by the reduction in temperature of the thermoplastic resins in the ink vehicle. Usually associated with heat-set, web offset presses.

HEMICELLULOSE
Alkali-soluble, non-cellulosic polysaccharide portion of a wood cell wall.

HI BULK PAPER
Book paper having the highest bulk available at a given basis weight.

HICKEY
An imperfection in a printed sheet brought about by a number of causes such as dirt, coating, ink skins etc., on the blanket or plate. The defect shows up as a small dot with a halo around it. When foreign material sticks to the printing press blanket or plate in an image area, it interferes with the transfer of ink to or from the blanket surface. The printed imperfection created can appear as a hickey (a white area around a dark center); can be caused by dirt on or around the press, dried ink skin, paper or coating particles, etc.

HIGH ALPHA CELLULOSE
A very pure form of wood pulp which is considered to have the same longevity as cotton or other plant fibers.

HIGH BULK PAPERS
Antique-finished book paper bulking from 440 to 344 pages to an inch for 45 lb. other weights are in proportion.

HOLDOUT
In printing, the extent to which a paper surface resists the penetration of nonaqueous fluids like ink, lacquers, oils or waxes. 1) In paper, the ability to resist surface liquid penetration. 2) In printing, the property of the paper to have low ink absorption, allowing the ink to set on the surface with high gloss; can create set-off with slow or poor ink setting.

HOT MELTS
Materials applied to paper or paperboard to produce fluid-resistant surface with high gloss.

HUMIDITY
Moisture vapor in the air, which affects paper printability. See relative humidity.

HYDRATION
The wetting of fibers, generally to swell them, and for their increased susceptibility to refining; any process of altering fibers to increase their ability to absorb water.

HYDROGEN BONDED AIRLAID
a technique utilizing the ability of cellulose fibers to bond when naturally occuring moisture in the fiber is removed while the fibers are in close contact; hydrogen bonding is generally done under high-temperature, high-pressure conditions.

HYDROMETER
Series of flotation type instruments used to measure the specific gravity or concentration of liquids. See Baume' hydrometer.

HYDROPHILIC
Describes the surface of a material that is easily wet by and compatible with water; "water loving"; for the opposite see hydrophobic. In offset lithography, the non-image areas of the plate are very water receptive and thus hydrophilic.

HYDROPHOBIC
Describes the surface of a material that is not easily wet by and actually repels water; "water hating"; for the opposite see hydrophilic. In offset lithography, the image areas of the plate repel water and are thus hydrophobic.

HYGROEXPANSIVITY
That property of a material which causes it to expand or contract when its moisture content is changed; as in paper, when the relative humidity of the surrounding atmosphere is changed.

HYGROMETER
Instrument for the measurement of the relative humidity of air.

HYGROSCOPIC
That property of paper or other substance which makes it prone to absorb moisture.

HYMNAL PAPERS
Strong, low-finish opaque book paper.

HYSTERESIS
That property of cellulose fibers, and therefore paper, that allows the percent moisture content at equilibrium with a specified relative humidity, to be dependent upon the most recent past relative humidity exposure; as if paper had a "memory," with the equilibrium moisture content closer to the most recent higher or lower relative humidity exposure, i.e., two pieces of paper that were last exposed respectively to high and low relative humidities, will have higher and lower moisture contents when brought into equilibrium at 50% relative humidity; dimensions will also vary accordingly.


 
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