Nail

Hard, keratinous, pointed or more or less oval, epidermal growth at the tip of a finger or a toe.

Nail (v); nailing

Nail leather to frames or boards to dry.

Nanofiltration (NF)

Process based on separation by membranes which retains particles of between 1 nanometre and 10 nanometres and results in the production of extremely pure drinking water.

Nappa

Soft, full grain gloving or clothing leather made from unsplit sheep, lamb, goat or kid skins. It is usually tanned with chromium salts and dyed throughout its substance.

Note: In France and Germany also made from side leather for footwear and leather goods purposes.

Nappalan

Woolled sheep or lambskins bearing the characteristics of nappa on the flesh side.

Natural dyestuff

Organic dyestuffs obtained from animal or vegetable matter, with very little, or no chemical processing.

Natural feel

Sensation felt by handling a material that has no artificial treatment. For example, a leather without any finishing.

Natural glue

Glue made from gelatine extracted from hides, bones or glue-stock.

Natural grain

Grain without any finishing coat showing its natural design and feel.

Natural grease

Natural fatty matter in hides and skins which is more or less removed during conversion to leather.

Near-Infrared Differential (NIR)

Spectrophotometry at wavelengths in the near-infrared region of the spectrum.

Neatsfoot oil

Oil from the washed split feet of cattle, as well as sheep and horses.

Neck

Part of the hide or skin nearest to the head.

Nephelometric Turbidity Unit (NTU)

Unit used in measuring the scattering function at various angles of particles suspended in a medium.

Neutralisation

Process of raising pH towards neutral from acidic zone, of a mineral-tanned leather after tanning by treatment with a solution of alkaline salt or buffer mixture.

Neutralise (v); neutralising

Raise pH towards neutral from acidic zone, of a mineral-tanned leather after tanning by treatment with a solution of an alkaline salt or buffer mixture.

Neutralising agent

Organic or inorganic alkaline salt, or alkaline buffer mixture, used to raise the pH of a mineral-tanned leather after tanning.

NF

See: Nanofiltration.

NIR

See: Near-Infrared Differential.

Nitrate (NO₃)

See: Nitrogen (total).

Nitrite (NO₂)

See: Nitrogen (total).

Nitrocellulose finish

Type of finish in leather production. The film-forming material is cellulose nitrate dissolved in organic solvents. Nitrocellulose is made from waste cotton by treatment with nitric acid. It is also know as collodion.

Nitrocellulose lacquer

Finish agents used in solvent-soluble dye and pigment preparations and as top coats. The basic product of these agents is nitrocellulose.

Nitrogen (total)

Total Nitrogen (TN) applies to all forms of nitrogen in water including the reduced forms and the oxidised forms.

·    The reduced forms correspond to Kjeldahl nitrogen (TKN): Organic nitrogen and ammonia nitrogen (-NH₄^-).

·    The oxidised forms correspond to the nitrous nitrogen (Nitrite NO₂) and the nitric (Nitrate NO₃).

NMR

See: Nuclear Magnetic Resonance.

No Observed Acute Effect Concentration (NOAC)

Acute exposure level at which there are no statistically or biological significant differences in the frequency or severity of any effect in the exposed or control populations. Acute exposures are usually characterised as lasting no longer than a day, as compared to longer, continuing exposure over a period of time.

No Observed Effect Concentration (NOEC)

Exposure level at which there are no statistically or biological significant differences in the frequency or severity of any effect in the exposed or control populations.

NO₂

See: Nitrite.

NO₃

See: Nitrate.

NOAC

See: No Observed Acute Effect Concentration.

NOEC

See: No Observed Effect Concentration.

Non tannin (NT)

Water soluble constituents of a vegetable or synthetic tanning material not taken up by the hide powder in the course of tannin analysis and hence regarded as incapable of tanning.

Non-ionic emulsifier

Emulsifier which, when dissolved in water, does not ionise.

Non-ionic surfactant

Surface active agent which produces electrically neutral colloid particles in solution.

Nonyl Phenol Ethoxylate (NPE)

Chemical compound often found in emulsifiers and wetting agents.

NOx

See: Oxides of nitrogen.

NPE

See: Nonyl Phenol Ethoxylate.

NT

See: Non tannin.

NTU

See: Nephelometric Turbidity Unit.

Nubuck

White or coloured, usually chrome-tanned leather, mainly used for uppers, made from cattle hides and calf, and sometimes pig skins, buffed on the grain side to give a fine, velvety surface.

Nuclear Magnetic Resonance (NMR)

Phenomenon exhibited by a large number of atomic nuclei, in which nuclei in a static magnetic field absorb energy from a radio-frequency field at certain characteristic frequencies. It gives information about the molecular structure.