Machine damage

Damage caused to hides and skins by the mechanical process of leather making.

Note: Fleshing, shaving and splitting machines.

MAK

See: Maximum Admissible Concentration.

Malpighian layer

Bottom and living epidermal layer, consisting of layers of closely-packed, cylindrical cells, connected by fibre-like processes (prickles) and constantly dividing, forming new cellular layers, thus pushing the older layers outwards.

Note: Stratum Malpighii or mucosum, or germinat(iv)um; Rete Malpighii.

Mange

Skin disease of animals caused by microscopic parasitic mites. Psoroptes and chorioptes species are non-burrowing mites and are relatively easy to treat. Scarcoptes and demodex species penetrate the skin, requiring repeated treatments to clear infestations.

Manufacturing bend

Sole leather bend produced primarily for the manufacture of new footwear.

Note: It is usually lighter in substance and more flexible, than a bend used for the repair of footwear.

Maple

Tree of the Acer species, such as Manchurian or Korean Maple, yielding the crystalline gallotannin “Acertannin”.

Note: Acer ginnala.

Marbled grain

Leather grain surface showing lighter coloured, indented pattern, resembling the veins on marble and corresponding to that of the finer underlying blood vessels. Suspected to be caused by climatic conditions and typical examples come from certain South American hides.

Marine salt

Common salt obtained by evaporation of sea water; contains calcium sulphate and magnesium chloride and may also contain halophilic bacteria, causing red heat and other defects.

Mark off (v); marking off

Displace, transmit or transfer the colour from a dyed material to a second material in contact with it.

Masking

Suppression of the reactivity of a complex, by the addition to its solution of a ligand capable of being more or less firmly held; thereby the metallic ion is less easily precipitated by alkali and the entry of the complex-active groups of collagen is hindered.

Mass spectrometry

See: Mass Spectrometry Detector Gas Chromatography (GC-MS).

Mass Spectrometry Detector Gas Chromatography (GC-MS)

Gas chromatography whose detection system is based on mass spectrometry.

Mass Spectrophotometer

Analytical device breaking down the sample into a series of ions with a specific mass which characterises the sample.

Material Safety Data Sheet (MSDS)

Sheet providing all relevant information about the risks associated with a chemical substance or a chemical preparation (physical and chemical properties, toxicity, eco-toxicity, safety prevention measures, etc.).

It is generally provided by the chemical supplier.

Matting

Production of a dull surface appearance without lustre.

Matting agent

Agent applied to leather in a finish process, which produces a matt surface.

Mature keratin,  (hard)

Harder, more highly condensed and more chemically resistant form of keratin, composing the hair and wool shaft, nails, horns, etc., and the outermost epidermal layers.

Maturity

State of being mature; fullness or perfection of natural development or growth; ripeness. When animals are raised under conditions that encourage rapid growth, a greater proportion of collagen is immature; the term maturity used in this context, refers to the stability of the crosslinks in the collagen molecule.

Maximum Admissible Concentration (MAK)

The maximal quantity/dose of specified substance or effect that is not considered an undue risk to human health.

Mechanical de-salting

Elimination of solid salt from hides or skins by mechanical means.

Mechanical screening unit

Fir First treatment station of effluent, its purpose is to protect the structure downstream against large objects which could create obstructions in some of the facility’s units. Also to easily separate and remove large matter carried along by the raw water which might negatively affect the efficiency of later treatment procedures or make their implementation more difficult.

Melamine

White crystalline high melting organic base; six-membered, carbon-nitrogen cyclic compound, with three amino groups.

Reacted with formaldehyde to make certain resin retanning agents.

Melanin

One of a group of reddish-brown to black substances forming the pigments in certain hair and epidermal cells.

Mellow (v); mellowing

To render a liquor gentle in action by passing several packs of hides through it.

Note: Lime liquor.

Mellow lime liquor

Lime liquor through which several packs of hides and skins have passed and which has good depilatory action, but does not produce excessive plumping.

Mellow tanning

Tanning the hide slowly, to produce a supple leather.

Membrane

Thin flexible, more or less permeable, sheet-like material, enveloping cell or organs, lining organs, or separating or connecting adjacent parts of an organism.

Membrane filtration

Generic  process of separation of suspended and dissolved solids from a liquid by means of a membrane.

Membrane stretching (Dynavac)

Stretching method for finished leather. The leather is laid flat on a rubber membrane and a second membrane is super-imposed mechanically over the first membrane and a vacuum is applied to bond both membranes tightly together. Radial stretching of both membranes gives increased area to the finished leather.

Memel

Black or brown curried hide leather, heavily embossed, frequently used for a heavy boot upper.

Mercapto compound unhairing

Removal of hair and wool from hides or skins by mercapto compounds.

Metal complex tanning agent

Tanning agent whose action depends upon the presence of complex metallic compounds, which are polynuclear and usually cationic, but also may be anionic.

Metal-complex dyestuff

Class of anionic dyestuffs containing complex-bound metal atoms (Cr, Cu, Fe).

Metallised leather

Leather given a metallic lustre by the application of metallic foils or powders.

Metamerism

Occurs when a coloured surface is examined under different lighting conditions and a marked change in its colour can be observed. Similarly, when two objects viewed under one particular illumination may have identical colour appearance, yet appear different when viewed under different illumination. This effect is known as illuminant metamerism.

MIC

See: Minimum inhibitory concentration.

Microfiltration

Process based on separation by membranes which retains particles of between 0,1 microns and 10 microns.

Microscopy

Interpretative application of microscope magnification to the study of materials that cannot be properly seen by unaided eye.

Microwave drying

Drying method using microwave energy. As water absorbs microwave energy, molecular friction causes evaporation of water inside the fibres of the leather by oscillation of water molecules. As the sticking effect of the leather fibres during drying is reduced, softer leathers are obtained.

Mid-sole leather

Bottom leather produced from bends or more usually shoulders or bellies of cattle hides and used in footwear construction between the inner and outer sole.

Note: The use of middle soles is mainly confined to heavy footwear.

Migrate (v); migrating

Move a substance in the structure of a material from one part of a system to another, by the effect of physical properties such as temperature and/or pressure.

Note: As the plasticiser in a finish layer moves into the leather.

Migration

Passage of a component in solution from the interior of a solid onto the surface, or onto another solid in contact with it, such as

dye from leather into a resin top finish.

See: Bleeding.

Milk kidskin

Soft fine-grained skin of a young unweaned kid; area up to 2½  square feet (sq. ft.).

Milk of lime

Suspension of calcium hydroxide in a saturated solution of calcium hydroxide.

Milk protein

See: Casein and modified casein.

Milling

Mechanical softening of damp or dry leather in a rotating dry drum. Mainly used for garment leather and soft upholstery leather.

Mineral tannage

Tannage with basic salts of chromium, zirconium, aluminium, iron, titanium, etc.

Minimum inhibitory concentration (MIC)

The bacteriostatic activity of a disinfectant is determined by an evaluation of the minimum inhibitory concentration (MIC). This is the simplest method of measuring inhibition of bacterial growth, and is similar to the test time serial dilution method for determining susceptibility to antibiotics.

Mis-shape

Damage caused to a hide or skin resulting in the shape being abnormal.

Note: Missing shank or neck/shoulder etc.

Mixed (vegetable) tannage

Combination of a (accelerated) pit tannage, a drum tannage and also a vegetable tannage employing a mixture of materials, such as myrabolams, algarobilla, valonia and chestnut and oak woods.

Mixed Liquor Suspended Solid (MLSS)

Suspended solids in activated sludge.

Mixed Liquor Volatile Suspended Solid (MLVSS)

Volatile part of the suspended solids in activated sludge.

MLSS

See: Mixed Liquor Suspended Solid.

MLVSS

See: Mixed Liquor Volatile Suspended Solid.

Mocha

Gloving leather with a fine silky suede finish on the grain side, made from the skin of hair sheep, originally the Arabian blackhead, but now also from other types of hair sheep; the usual method of removing the grain being by frizing in the limed state. Generally alum or aldehyde tanned.

Modified casein

Casein, a protein obtained from milk, modified by means of a polyamide. The use of modified casein improves desired properties of finish preparations.

Modifier

Finishing auxiliaries added to the top coats or applied as separate top coat to give the leather desired surface handle properties.

Moellon

Water-in-oil emulsion, or a degras, containing the partially oxidised oil (hydrophilic train), extracted by pressing marine oil-tanned skins.

Mohlman index

Also called Sludge Volume Index or SVI. It is the ratio of the volume of sludge after 30 minutes of settling (cm³) and the suspended solids (SS) in grams, present in this volume. Activated sludge that settles easily has an SVI of 50 to 100 cm³.g^-1.

Moisture content

Quantity of water in a mass of a material expressed in percentage by weight of water in the mass. Note: Leather, soil, sewage, sludge or screenings.

Molasses

Residual product from the manufacture of cane sugar, in the form of a black, viscous, sugar-containing liquor; used to prepare reduced chrome liquors.

Mononuclear complex

Complex ion containing one central atom to which the ligands are attached.

Mordant (v); mordanting

Apply a substance, prior to dyeing with certain types of dyestuffs, to increase their fixation by a material to achieve a desired colour.

Mordant dyestuff

Dye that, for its fixation, needs a mordant which, in the case of leather, is a metallic salt.

Morocco

Vegetable tanned goat skin leather with characteristic grain pattern developed naturally or by hand boarding or graining only.

Note: The commonest and most characteristic grain is hard grain.

By long usage, especially in the fancy good trade, denotes goat skin of any vegetable tannage that has been hand boarded in the damp condition, but in the strict sense it should be limited to goat skin tanned exclusively with sumac. See: Hard grain goat.

Morocco

Leather made from vegetable tanned goat skin with a grain resembling that of genuine Morocco, but produced otherwise than by hand boarding, for example, by embossing or embossing followed by boarding.
Note: Should be termed "Morocco grained goat" or "Assisted Morocco".

Mottled

Drawn grain in lamb or sheepskins is often referred to as mottled. Portions of the skin are raised and between the raised areas the skin is shrunken and often darker in colour. Can be caused when skin are being giving a paddle liming after a lime/sulphide paint and the paddle speed is too fast.

Mould (v); moulding

To give the required shape to a material by introducing it in a liquified or plastic state into a mould where it solidifies, such as in the case of forming rubber soles on footwear.

Moulding injection

Method of manufacturing certain objects, in which various components, normally liquid or liquified by heating, are forced into a mould where they solidify, such as in the case of soles or whole shoes.

Moveable guard

Guard generally connected by mechanical means, such as hinges, to the machine frame or an adjacent fixed element and which can be opened without the use of tools.

MSDS

See: Material Safety Data Sheet.

Mucin

Any of various glycoproteins forming the main constituent of mucus, a slimy substance that contains mucin and other glycoproteins and is secreted by the mucous glands and membranes of animals for protection, lubrication, etc., (mucins interferon, fibrinogen).

See: Glycoprotein.

Mucopolysaccharide

Group of linear, high molecular weight saccharides, built up of repeating pairs of a hexose sugar and an N-acetylhexosamine (neutral mucopolysaccharides) or a hexuronic acid and a N-acetylhexosamine which may be esterified with sulphuric acid (acid mucopolysaccharides). May occur free or combined with covalent links with a small proportion of protein other than collagen or elastin. Present in the ground substance of connective tissues and in cartilage.

Mucoprotein

Mucoprotein = Proteoglycan, a protein that is covalently bonded to one or more glycosaminoglycan chains.

See: Glycosaminoglycans.

Mud

Deposit formed in a vegetable tan liquor, especially when containing ellagitannins.

Mud-cured

Cured by application to the flesh side of muddy salt-earth, or khari salt, and drying; it is alleged that sometimes mud completely replaces the salt (Historical interest).

See: Khari salt.

Mutagen

Substance or preparation which, by inhalation, ingestion or skin penetration can cause hereditary genetic modifications or increase their frequency.

Mutagenic

Substance known to be mutagenic to man. One which has enough elements to establish a cause and effect relationship between man’s exposure to this substance and the appearance of hereditary genetic modifications.