Oo

obliteration
the ability of an opaque overprint to hide completely the color underneath; also sometimes referred to as obliterating power.

object
a graphic or picture that is embedded in a document file using object linking and embedding (OLE).

object linking and embedding (OLE)
a standard method for inserting an object into a document, where the document retains a connection or link with its original program.

object oriented
a graphic image that is created with mathematical descriptions instead of pixels.

obscure
glass that has been made translucent by grinding, sandblasting, or acid etching.

observer, standard
spectral response characteristics of the average observer defined by CIE.

obsidian
a natural glass that is produced by volcanic action.

occupational exposure limit
minimum allowable concentration of toxic substances in workroom air to protect workers who are exposed to toxic substances over a working limfetime.

Occupational Safety and Health Act (OSHA)
a US federal law enacted in 1970 to protect workers from industrial hazards.

ochre
a naturally occurring yellow iron oxide used as a pigment in ink formuations.

OBR
acroynm for optical bar reader or optical bar recognition; refer to optical mark reader (OMR).

OCR
acronym for optical character reader or optical character recognition; a scanner that provides a means of reading printed characters on documents and converting them into digital codes that can be read by a computer.

OCR ink
ink that is composed of low reflectance pigments such as carbon black that can be read by OCR equipment.

OD
outside dimension of an item.

ODB
acroynm for outdoor board.

ODC
acroynm for ozone depleting chemical or compound.

ODC (On-Demand Color)
this term typically refers to short run color printing. These processes include ink-jet, electrostatic and direct-to-press.

OEL
acroynm for occupational exposure limit.

OEM
acroynm for original equipment manufacturer.

off color
color variation from a sample or specification.

off contact distance
the space between the bottom of the screen and the top of the substrate; also refer to snap-off.

off contact printing
screen printing with the print screen adjusted slightly above the substrate so that it does not make contact with the substrate except during printing.

off square
a material where two or more corners deviate from an exact 90º angle.

offset
(1) an indirect printing form; (2) the unintentional transfer of ink to the bottom of the printing screen, the back of a succeeding sheet, or other undesired surface.

offset paper
a grade of paper manufactured in a range of weights in white or light colors with good dimensional stability, cleanliness, and pick resistance; alterative term for uncoated book paper.

offset printing
planographic printing by indirect image transfer.

offset stock
paper manufactured to accept offset printing ink; also referred to as offset paper and uncoated book paper.

offsetting
refer to offset.

ogee
a distortion of an image using an S-shaped curve as one baseline, gives image a wavy look.

ohm
unit of electrical resistance used for measuring or testing the capacity of resistance; the unit of resistance equivalent to the resistance of a conductor in which one volt produces a current of one ampere.

Ohm’s Law
the current in a curcuit is directly proportional to the voltage E, and inversely proportional to the resistance R: E=IR, I=E/R. R=E/I.

ohmeter
an instrument used for measuring electrical resistance in ohms.

ohms per square
a means of evaluating the resistance value of an ink mixture, or the resistance value of a square of ink one mil thick.

oil absorption
the quantity of oil required to completely wet a definite weight of a given pigment, forming a paste.

oil-in-water emulsion
an emulsion that has water as the external phase and an oil as the internal phase.

oil soluable resin
a resin that will dissolve in a drying oil at slightly elevated temperature to yield an homogenous film.

oiticica
a drying oil used in ink formulations made from seeds of licahia rigida tree; similar in properties to tung oil.

OJT
acroynm for on-the-job.

OK sheet
a press sheet that closely matches the original proof and has been approved by the customer, used as a guide to judge print quality as production run progresses.

OLE
acroynm for object linking and embedding.

olefin
a chemical family of unsaturated hydrocarbons; also refer to polyolefin.

oleo resinous
describes solvents or inks derived from crude oil, or having vehicles compounded from crude oil derivatives.

olephilic
oil receptive.

olephobic
oil repellent.

oligomer
(1) a multiple unit molecule consisting of several monomeric units in chemical union; (2) base resin used in UV ink formulations.

OMR
acroynm for optical mark reader.

on-contact printing
screen printing with the print screen in contact with the substrate both during and after printing.

one-man squeegee
a squeegee mounted on a counter balanced device so that the operation of very large squeegees can be accomplished with a minimum of effort.

one-side finish
paper finished on one side only.

one-way screen
a halftone screen having lines running in one direction only.

oozing adhesive
adhesive that is forced out from between the face film and backing sheet of pressure sensitive laminates by pressure in die or guillotine cutting.

Op art
art form using arbitrary patterns of shape, color, and value to create optical illusions or effects that suggest movement.

opacifier
a chemical agent added to a material to make it opaque.

opacimeter
a test instrument used to measure the degree of opacity or show through.

opacity
a state where a printed film or a substrate does not permit the passage of light; the state of being opaque.

opaque
(1) an area or material that completely blocks out unwanted light; (2) red or black liquid used to blockout or cover unwanted clear or gray areas on a negative; (3) white liquid used to cover unwanted black images in an original copy; (4) to paint out areas on a negative that are not to print, refer to blockout; (5) the property of paper that makes it less transparent.

opaque edge (safe edge)
the edge of a sheet of photoscreen stencil film that has been covered with opaque tape or other opaque instrument, where during exposure develops and washes out with the design portions of the stencil, thus providing a narrow space for handling of the sheet in order to minimize handling damage.

opaque ink
a screen printing ink that conceals the color beneath it.

opaque vinyl
a vinyl that is pigmented, so no light passes through it.

opaquing
refer to opaque.

open area
refer to aperture percentage.

open circuit
the lack of electrical contact in any part of the measuring circuit, usually indicated by rapid large jumps in potential, followed by an off-scale reading.

open cutter and creaser
a platen press used for die cutting and creasing.

open end envelope
an evelope that opens on the short dimension.

open end yarn
yarn produced without being spun; a hard, uniformly blended yarn considered inferior to ring-spun yarn.

open gold
a nondrying gold.

open kiln
a kiln that exposes the ware directly to the flame.

open side envelope
an envelope that opens on the long dimension.

operating force
the force required to achieve contact resistance; the amount of force required to complete a switch closure in a membrane switch.

operational characteristic curve
a graph that dispalys the probability of accepting a sample lot as a function of the quality of the lot in process.

OPS
acroynm for oriented polystyrene film.

optical axis
an imaginary line that runs through the focus and center of the lens of a camera.

optical brightener
a chemical used to make white garments whiter.

optical character recognition (OCR)
electronic equipment that converts printed, handwritten, and graphic information into a form that can be read, interpreted, and displayed by a computer.

optical center
the center of a rectangle as it appears to the human eye, usually a point slightly above the geometric center or about 2/5 from the top of the rectangle.

optical comparator
a visual inspection device that uses large ground glass screens for imaging; offers a much larger view than a mircoscope.

optical mark reader (OMR)
electronic equipment that scans, interprets, and converts bar coded information into a machine readable form.

optical registration
a register system employing an optical scanner for obtaining the correct positioning of substrate on a press.

optical resolution
the maximum physical resolution of a device. Optical resolution provides better quality than interpolated resolution of the same number, which uses software to create additional image information.

optical reverse
the use of mirrors to reverse a camera image.

optical sampling rate
the number of samples in pixels per inch that are taken by a scanner per linear distance, as determined by the CCD array, the optical system, and the motion of the carriage.

optimum tension level
the most favorable screen tension required for a given set of printing conditions.

optimum thickness
the best, most desirable thickness allowable by specification.

orange peel
very small elevations and valleys in an ink film, coating, or glaze that failed to flow out properly, surface characteristics resemble the texture of an orange peel.

organdy
a multifilament woven cotton mesh once used for screen mesh; no longer used in the industry.

organic
derived from living organisms; pigment or chemical compound comprised of raw material from animal, plant, or carbon origin.

organic color
raw materials derived from animal or vegetable origin.

organic peroxide
an organic compound that contains a structural deviation of hydrogen peroxide, where one or both of the hydrogen atoms has been repaced by an organic radical.

organic pigment
raw material colorant that is derived from coal tar or its derivatives,usually stronger and brighter than inorganic pigments.

organic solvent
organic material including diluent and thinner that are liquid at standard conditions and are used as dissolvers, viscosity reducer or cleaning agent.

organosol
a suspension of resin particles in origanic solvent typically made with vinyl resin or plasticizers.

orientation
(1) the direction a page is printed, horizontal (landscape), vertical (portrait); (2) the condition of polymers being positioned in a direction parallel to the fiber length, as in a polyester mesh fiber that has been highly tensioned.

oriented polystyrene (OPS)
a transparent glass-like polymerized styrene material, not modified for impact, heat resistance, solvent and chemical resistance.

origin
place marking the zero coordinate on the x, y, or z axis.

original
a design, material, or subject to be copied or reproduced.

original equipment manufacturer (OEM)
(1) a company that sells goods to another company for use as components in their own equipment or for resale to end user; (2) a firm that licenses other companies to sell their products.

orthochromatic (film)
(1) photographic surface insensitive to red but senstive to ultraviolet blue, green and yellow rays; (2) electromagnetic wavelengths between 375 and 560 nanometers.

orthotropic
having three mutually perpendicular planes of elastic symmetry.

OSHA
acronym for the Occupational Safety and Health Administration of the U.S. Department of Labor or Occupational Safety and Health Act.

Ostwald system
a method of color notation based on a central gray scale surrounded by solid colors in horizontal and vertical rows.

ounce, avoirdupois
a unit of measure of weight; an avoirdupois unit is equal to 28.350 grams, abbreviation is oz.

ounce, fluid
refer to fluid ounce.

ounce, troy
a unit of weight for precious metal materials used by glass decorators, equal to 31.1 gm. or 1.097 oz. avoirdupois.

outdoor board (ODB)
a weatherproof board or paper used for outdoor advertising signs and displays.

outdoor durability (exterior exposure resistance)
the ability of a printed product to resist change during exposure to outdoor environmental influences; also refer to weatherability.

outgas
the characteristic of a solid or liquid to vaporize under heat.

outgassing
the release of vapors from polycarbonate sheet, resulting in bubbles forming between the sheet surface and applied vinyl film or ink film.

outline halftone
a photograph shot as a halftone with an outline mask to eliminate the background.

outline positive
a film positive with all areas except the desired subject having all detail eliminated, usually by opaquing the undesired portions on the negative, produces a stencil that does not print areas beyond the outline.

outlining
(1) a photographic technique of converting solid letters to outline letters; (2) scribing or drawing the shape of an object as in tracing with a thin line.

out-of-register
refer to misregistration.

overcure
undesirable condition where an ink or coating is overexposed to the curing process.

oven dry
a condition when paper has been dried in an oven at 105 plus or minus 3 degrees Centigrade, until its weight has become constant within 0.1 percent.

overexposure
the subjection of photosensitive material to light source for a longer period than is necessary to accomplish the desired result.

overfiring
heating to a temperature that causes deformation, bending, or discoloration.

overglaze
complex compound of lead borosilicates and alkali borosilicates that is applied over previously fired glaze and then refired.

overglaze enamel
screen printing ink applied to ceramic or glassware as a finish to impart high gloss or color change.

overlaminate
a protective clear film that extends an image's outdoor life and enhances its visual quality.

overlap
to make shapes to lap one color over another to ensure that subsequently printed colors will appear in register.

overlap lock
a display lock for constructions that require placement of lock within the display rather than at its edge.

overlay
top layer graphical interface of a membrane switch.

overlay of colors
the printing of a color on top of a preceding color.

overprinting
copy or graphic printed directly over an area that already has been printed.

overprint varnish
a clear, screen printable compound printed as a protective coating over a design.

overrun
copies of printed material that exceed the number ordered by the customer.

oversampling
scanning at more than an optimum sampling rate. See also subsampling.

overshoot
the number of degrees that a process involving heat exceeds the set-point when raising to the set point temperature.

oversize
substrate made larger to allow for trimming to ordered size.

over-travel
the additional movement of a rubber key pad or metal dome after making contact with the circuit.

oxidation
the effect produced by contact with oxygen, either in the atmosphere or introduced in more concentrated form, such as drying in some screen printing inks or deterioration of photographic developers in open trays.

oxide colors
inorganic or mineral base pigments used in porcelain and vitreous glass enamel colors.

oxidize
to combine with oxygen.

oxidizer
a chemical that initiates or promotes combustion in other materials, thereby without the aid of an external ignition source causing fire either of itself or through the release of gases.

oxidizing agent
material that causes oxidation of an atom or ion and is reduced in the process; (oxygen is a common oxidixing agent).

oxidizing atmosphere
(1) sufficient oxygen content in a lehr to produce or support combustion; (2) air volume containing oxygen sufficient to promote drying of wet ink applications by oxidation; (3) an environment with an over supply of oxygen.

oxidizing ink
screen printing ink that changes from wet to dry state on contact with atmospheric oxygen.

oxy
oxidizer, any substance used to unite with oxygen, or which causes another to oxidize.

oxygen inhibition
the effect of oxygen to terminate or slow a polymerization reaction by deactivating radicals.

oz
abbreviation for ounce.

Ozalid
a tradename describing a method of copying page proofs from paper or film.

ozone
gaseous form of oxygen (O₃) containing three atoms to the molecule generated by electric spark or a high-voltage discharge across a stream of air, causing oxidation of metals and other materials.

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