Glossary

Please click on the letters for more information

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

UL

Underwriters’ Laboratories. USA.

ULTIMATE ADHESION

The maximum adhesion possible from a pressure sensitive adhesive. Refer LM.

ULTIMATE STRENGTH

The maximum stress a material is capable of withstanding under specified load or tension. Refer NS & LM.

ULTRA VIOLET - ULTRAVIOLET - UV

Zone of visible radiation(s) beyond the violet end of the spectrum of visible radiations. Since UV wave lengths are shorter than the visible, their photons have more energy, enough to initiate some chemical reactions. Radiation from a source such as a high pressure mercury vapour lamp made of quartz, emits UV light in the 315 to 400 nanometre range (just below visible light). This light is used to trigger a chemical reaction in the ink on a press, and causes the ink to cure. Curing time is usually 1/40th of 1 second. Refer IM.

UNBLEACHED

A term applied to paper or pulp which has not been treated with bleaching agents.

UNDER CURE

Degree of cure less than optimum. May be evidenced by tackiness, softness, off-colour or inferior physical properties of a coating.

UNDERCUT ANVIL - Also STEPPED ANVIL

Die station base roller that has had the ‘bearer’ area diameter reduced in order to allow the blades of a rotary die to cut deeper than was originally intended.

UNDERCUT PLATE CYLINDER - See PLATE CYLINDER

UNDER-RUN

Production or delivery of labels which falls short of the quantity specified by the client order. Refer NS.

UNWIND

Mandrel and brake device from which a roll of labelstock is unwound and fed into a web press.

UNWIND ADHESION

The force required to unwind self wound laminating film from a roll under prescribed conditions.

UPC SYMBOLS - See BAR CODES

UV - See ULTRA VIOLET

The part of the spectrum wherein the wavelength of light is shorter than that of visible light.

UV CURING

A system which uses ultra violet rays to affect a curing process.

UV INHIBITOR

A chemical additive that increases resistance to degradation caused by UV light.

UV INK

Solvent-less, 100% solids ink that is cured by ultra violet radiation and then becomes chemically inert. Refer IM.

UV RESISTANCE

The ability of any material to withstand extended exposure to sunlight without degradation, hardening or excessive discolouration.

UV STABILISER

Any chemical compound which, when mixed with a thermoplastic resin, selectively absorbs UV rays.

UV VARNISH

Lacquer or varnish usually applied over printed web used as a protective layer that is cured by exposure to a high intensity UV light source. Refer IM.