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DuPont Packaging Graphics - North America

Flexo Glossary

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- N -

Nanometer A unit in which wavelengths of light are expressed. One nanometer is one-billionth of a meter.

Naphthas Alipathic hydrocarbon solvent derived from petroleum such as hexane, V M & P naphtha, etc. Characterized by low K.B. values. Will swell natural or butyl rubber and will have slight effect on Buna-N or Neoprene.

Negative A photographic image of originals on film in reverse from that of the original copy. Dark areas appear light and vice versa.

Neutral The absence of acid or alkaline activity in a material. The presence of an equal concentration of hydrogen and hydroxyl ions. Materials have a pH of 7.

Nip Line of contact between two rolls.

- O -

Offset The transfer of an improperly or incompletely dried ink from the face of the print to the back of the stock on top of it in the roll or pile. The accidental transfer of ink from the idler or other rolls in a press to the web.

Offset Printing A planographic printing process where hydrocarbon based inks are transferred from an aluminum printing to plate, to a rubber printing blank and then to the printing substrate. Offset printing is a high quality, high speed printing process that is usable with a limited range of paper based printing substrates.

Opaque Impervious to light rays. A paint, exhibiting light obstructive qualities, used to block out areas on a photographic negative not wanted on the plate. To apply opaque materials.

Organic Solvent The medium used to dissolve a substance which contains compounds in the field of chemistry containing carbon.

Out-Of-Contact An air bubble/pocket between the film and plate during exposure. This leaves an unsharp image and/or loss of image detail. Insufficient vacuum or matte level of the film can contribute to this defect.

Ozone A form of oxygen generated by electric motors and corona discharge units which attacks double bonds in photopolymer plates. This causes cracking of the plates and reduces the plate life.