Leather Cleaning and Restoration Glossary - Commonly use Industry Terms and Definitions

Abrasion
The wearing-away of a solid surface or coating material by friction.

Abrasion Resistance
The abilities of a solid surface or coating material to resist abrasive wear.

Absorb
To take or draw within, usually resulting in a physical change of the absorbing material.

Absorption
The property of leather or fabric or other material which enables it to attract and hold gases or liquids within its pores by capillary, osmotic, solvent or chemical action. See adsorption.

Acetone
A volatile, flammable dry solvent used primarily to dissolve synthetic resins, such as nail polish, airplane glue, acrylic paints, etc.

Acid
Any chemical that undergoes dissociation in water with the formation of hydrogen ions. Its properties include the ability to react with bases or alkalis to form “salts”. Acids have a bitter or sour taste and may cause severe skin burns. Acids turn litmus paper red and have a pH values that are less than “7” on the pH scale.

Acid Dyes
Negatively charged coloring material used for dyeing.

Active Ingredient
Those components of a compound or solution that enable it to perform a specific function, as opposed to inert ingredient that serves as fillers or extenders.

Adsorbent
A material capable of adsorption.

Aesthetics
In textile, properties perceived by touch and sight, such as the hand, color, luster, drape and texture of leather.

Agent
An ingredient that causes activity or reaction to take place (e.g. a cleaning agent that causes cleaning to occur.

Alcohol
A class of colorless, volatile flammable organic dry solvents containing one or more hydroxyl groups (OH-). Alcohols are used as co-solvents in some cleaning or spotting compounds.

Aliphatic Solvent
A non-polar dry solvent classification that includes solvents produced by refining petroleum products (e.g. odorless mineral spirit).

Alkali
Any soluble chemical substance that forms soluble soap when mixed with fatty acids. Alkalis are also referred as “bases” and they may caused severs skin burns. Alkalis turn litmus paper blue and have a pH value that is above seven “7”.

Alkalinity
The property of water-soluble substances that causes the concentration of hydroxyl ions (OH-) in water based solution to be higher than the concentration of hydrogen ions (H+). Soap is mild alkaline and detergent may be formulated with any desire degree of alkalinity.

Alum Leather
Tanning process using a combination of alum, salt, egg yolk and other substances, known as baseball leather or white leather.

Ammonia
An alkaline gas composed of nitrogen and hydrogen to form ammonium hydroxide. Ammonia is included in some hard surface cleaner formulations to assist in degreasing, wax stripping and general soil removal. It denatures leather.

Angora
The soft hair of the Angola goat, native to Anatolia and Turkey, often called mohair.

Aniline Dye
In general, the term refers to an organic dye; however, it means an oily, poisonous, liquid amine, C6H5NH2, obtained chiefly by the reduction of nitrobenzene and used chiefly in making dyes.

Aniline Dyed
Process of coloring leather throughout using transparent non-toxic dyes.

Aniline Dyed Leather
Full grain leather colored with nontoxic aniline dye, rather than pigments or other opaque materials. Aniline dyes completely penetrate the hide so that color is almost uniform on both sides.

Animal Fibers
A term used to distinguish protein or natural fibers obtain from animals. Examples include alpaca, angora, goat hair, camel hair, cashmere, cow hair, horse hair, fur, mohair, rabbit hair, silk, vicuna, etc.

Anion
Negative charged ion.

Anionic Surfactant
A surface active agent usually derived from reacting aliphatic hydrocarbons and alkali to form salt, and in which detergency and other properties depend in part on the negatively charged ion of the molecule. Anionic surfactants are sensitive to water hardness and are particularly effective in emulsifying oily soils and in suspending particulates. Anionic surfactants are widely used in high-foaming detergents.

Antique Finish
Full grain leather that generally is hand rubbed with black dye after the base coat has dried. This technique is used to bring out the natural markings in the hide and highlight the grain.

Appearance
A description of a substance at normal room temperature and atmospheric conditions. Appearance may include the color, size, and consistency of a material.

Appearance Retention
The ability of a fabric to retain its original aesthetic, color and construction integrity.

Beamhouse Operation
The steps in the production of leather between curing and tanning are collectively referred to as beamhouse operations.

Belly
Leather terminology indicating that part of a hide from the underside of an animal.

Bleach
A cleaning, sanitizing and color removing material that functions through a chemical reaction called oxidation. Bleaches are often used with detergent, or by themselves to break chemical, rather than physical bonds, as detergent do. Examples include Bleach-9.9.

Bleeding
The migration or transfer of dyes within or from wet leather, usually due to improper dyeing (fixing), from the use of poor dyestuff, or from exposure to high pH chemicals. Leather that bleed when wet may stain fabric that comes in contact with them; or color may be transferred from one portion of a multi-colored leather to another.

Blue (In the blue)
Leather terminology that applied to hides or skins that have been chrome-tanned, but not finish.

Body
The firm, full feel of leather, See also “hand”.

Bolster
A loose pillow.

Cation
Positive charged ion

Cattle Hides
Leathers made from the hides of cows, steers and bulls.

Chrome Tanned
Leather tanned with chromium salt, resulting in soft mellow upholstery leather.

Chrome Tanning
Leather tanned using chromium salts, most widely used tanning process.

Cleanability
The ability of a leather or fabric to release soil and stains without damages to the leather, fiber, color or backings when clean using appropriate processes.

Cleaning
The traditional activities of removing contaminants, pollutants and undesired substances from surface to reduce damages or harm to human health of valuable materials. Cleaning is the process of locating, removing and properly disposing of unwanted substances from leather or fabric material.

Color Matching
The proper coordination of color hue and shade depth. Critical to color matching are: the light which the color is compared; the surface texture of the object being and the surface luster of the object being matched.

Color Removal
Oxidizing or reducing agents that is sufficiently reactive to remove color or stains from leather without destroying it.

Combination Tanning
The use of both vegetable and chromium is an example of combination tanning.

Compound
A combination of substance which results in a reaction that forms new substances that differ from either of its components.

Concentrate
The undiluted form of a product that is normally cut or mixed with water.

Concentration
The relative amount of a substance when combine or mixed with other substances.

Corrected Grain
1 - Leather on which the outer surface of the grain has had another grain pattern embossed.
2 - Leather on which the outer surfaced of the grain has been lightly removed by sanding.

Cowhide leather
A term applied specifically to leather made from hides of cows, although it also is generally used to designate any leather tanned from hides of animals of the bovine species.

Crocking
Term used to describe the wet or dry transfer of excess color, rubbing off as the result of improper dye penetration or fixation, the use of improper dyes or dyeing methods or insufficient washing (rinsing) and treatment after dye application. Generally, dyes are transfer from the crocking leather especially suede and nubuck to another fabric or surface. Crocking is easily detected by wiping a clean, white cloth over an unused portion of the leather 10-12 times.

Crushed leather
Leather, which has had the natural grain accentuated during manufacture by plating, boarding or other mechanical processes.

Crust
Leather that has been tanned, dyed and dried but not finished.

Deflocculation
In cleaning, this term refers to separation of soil from a surface on which it is deposited, normally accomplished with detergent action.

Degrade
To impair with respect to some physical properties of a material.

Degreaser
A degreasing detergent compound designed to be used primarily on penetrated heavy, oily soils.

Dehairing
The removal of hair and epidermis before tanning by chemically soaking the hide

Deliming
Returning the skin from strong alkalinity towards neutral.

Detergent
A cleaning agent. Usually the term detergents refers to a prepared compound that ma\y include surfactants, builders, dry solvent, softeners, brighteners, fragrances, etc.

Dilute
Making a substance less concentrate by addition of water.

Dilution Ratio
The ration at which a cleaning agent is diluted in water for its recommended effective usage, often expressed as a number such as 1: 80, referring to parts of the chemical dissolved in parts of ( e.g. 1: 80 = 1 part chemical to 80 parts water).

Discoloration
A condition in which existing dye structure have been altered or removed.

Distortion
Any of alternations in the appearance of leather surfaces.

Do-It-Yourself (DIY) Cleaning
Cleaning done by non-professional leather owners.

Drum Dyed
A dyeing process in which leather is immersed in dye then tumbled in a rotating drum, ensuring maximum dye dispersion throughout.

Dry Cleaning
A cleaning process in which inorganic solvents, such as chlorinated or aliphatic hydrocarbons and other dry solvent compatible detergents, are used as the cleaning medium, rather than water.

Dry Foam Cleaning
A minimum-moisture cleaning method in which foam is used, following by dry soil removal (vacuuming).

Dry Rot
The slow, progressive deteriorating effect of microorganism (fungi) over a period of time under minimum-moisture conditions on organic (especially cellulose) textile fibers. Eventually, dry rot causes a loss of strength and fabric integrity.

Dry Solvent
A non-water liquid (hydrocarbon) that has the ability to dissolve oils and grease.

Dust Cover
An inexpensive spun or plain woven fabric that covers the bottom of upholstery furniture or box springs.

Dwell Time
See “soil suspension principle”.

Dye
A soluble, color absorbing/reflecting material. Dyes differ in: their resistance to sunlight, perspiration, cleaning agents, atmospheric gases, their solubility; their affinity for different fibers; and their method of application.

Dyeing
Coloring by means of soluble dyes.

Dyestuffs
A water-soluble or insoluble, highly colored substance that is capable of permanent physical or chemical attachment to leather. Most dyestuffs are applied from water-based solution.

Embossed leather
Hides or skins finish with designs stamped on by etched, engraved or electrotyped plates or rollers. Embossing is used extensively on fancy pocketbook leather, upholstery and bag leathers, as well as splits and on shoe upper leather. Embossed designs may be an imitation of the natural grain of different animal skins or designs of an artificial nature.

Epidermal
Layer closest to the hair.

Epidermis
It is the outer epithelial layer of a skin. The epidermis is the non sensitive, nonvascular layer that covers the dermis.

Fading
Gradual, irreversible loss of color intensity, usually due to exposure to light (actinic radiation, especially direct sunlight); or from contrast between dyes and various soils or oxidizing gases (ozone); or fumes from certain liquids (oxides of nitrogen, sodium hypochlorite), etc. Fading may occur locally or throughout the entire leather, depending on exposure to outside agents and airflow. Windows and the general orientation of the structure may be a contributing factor, since the greatest potential for sun fading is from a south west exposure with the least from a north or northwest exposure.

Fahrenheit (F)
A scale for measuring temperature. On the Fahrenheit scale, water boils at 212° and freeze at 32°. Fahrenheit is converted to degrees centigrade (Celsius) by subtracting 32, and multiplying by 5.

Fake Fur
Fake, simulated or manmade furs are fabric that appears to be like animal skins. Most are woven or knitted fabrics made of mohair, wool, rayon, acrylic and blends of fibers.

Fastness
The property of a dye which allows it to retain its color when the dyed textile is exposed to light, abrasion, atmospheric gases, cleaning or other color destroying agents.

Fat Wrinkles
Natural wrinkles only visible in the top grain leathers that are part of the unique beauty caused by fat deposits in the animal.

Fatliquoring
The process of replacing oils that have been removed from the hide during processing and which also gives the leather its final pliability and increase in tensile strength.

Fingerprints
The natural markings of a hide.

Fleshing
The method prior to tanning where the excess tissue and fat are removed from the flesh side of raw hides.

Full Aniline
Leather receiving its color from transparent dyes, though it may receive a topical stain and or water repellent.

Full Grain
The outer layer taken from the hair side, with only the hair and surface debris removed. Also it is referred to as “full top grain”.

Fundamentals of Cleaning
Fundamentals of cleaning includes Chemical Action (preconditioner/chemical application); Temperature (to excite chemical molecules and speed activity in suspending soil; Agitation (for maximum distribution of cleaning chemicals); and Time (“dwell” time required for cleaning agents to fully suspend soils).

Furniture condition report form
A form used to list conditions that may adversely affect the outcome of the cleaning procedure. It is filled out by the technician during the inspection and signed by the customer prior to the beginning of the cleaning.

Grain
A reference to the outer or hair side of a hide or skin. Grain also refers the pattern of the outer surface after the hair or wool and epidermal tissues have been removed.

Grained Leather
Leather on which the original natural grain has been highlighted by a finishing process.

Grooming
The process of nap setting following cleaning or after treatment application.

Hairiness
The extension of fibers above the normal level of the used surface or pile or texture fabrics (suede). Hairiness usually is not removed by brushing or vacuuming.

Hand
Term used to describe the softness and sense of leather.

Hide
Skins of large animals over 35 sq. ft., usually from cattle.

Hides
Pelts of large animals, almost always meaning cattle, in contrast to “skins”, which refer to the pelt of young or small animals.

Imitation
Varieties of materials that have been made to resemble leather, mostly rubber or plastic-coated fabrics.

Imitation Leather
Materials made and finished to resemble leather. Included are coated fabrics, rubber and rubber compositions and plastic materials.

Ion
A molecule-size particle that has either a positive or negative charge.

Leather
A hide or skin of a mammal, bird, fish or reptile that has been tanned into a non-perishable material, either with or without the hair removed. Leather is also made from a hide or skin that has been split into layers before or after tanning. But if the tanned hide or skin is disintegrated into fibrous particles, either mechanically and /or chemically or into small pieces or powders and then, with or without the combination of binding agent, is make into sheets or forms, such materials are not leather. Leather may have surface coatings of a reasonable amount, but beyond this, the resulting products shall be described as a laminate or composite. The term “laminated leather” should not be used if the leather content is less than two-thirds of the total thickness.

Liming
The process of removing hair from a raw hide through the use of chemicals.

Love Seat
A small sofa or sleeper that accommodates two people.

Maintenance Cleaning
This includes routine procedures such as vacuuming, attending to spots and polishing surfaces as required. Maintenance helps to keep the furnishing in a more attractive and healthy state, while preventing premature wear.

Material Safety Data Sheet (MSDS)
Document that chemical manufacturer must supply with their hazardous products to describe the general properties, its hazards, and how to safely use, handle and store it.

Migration
Gradual movement of moisture, usually on a horizontal plane, as it is absorbed by material outwards from its source or point of origin. See also “wicking”.

Mildew Resistant
Fabric treated to make it resistant to fungi; e.g. mold and mildew.

Mixture
Any combination of two or more chemicals, if the combination is not, in whole or part, the result of chemical reaction (in which a “compound” is formed).

Mohair
The long, lustrous, strong hair of an Angora goat.

Nap
The surface of suede or nubuck.

Native Hides
Hides from steers, cows or bulls which are free of brand marks.

Natural Grain
Leather whose grain has not been altered in any way and the natural appearance of the grin is evident. (See Full Grain).

Neutral
A chemical state that is neither acid or alkali; seven in pH value.

Neutral Cleaner
A cleaning agent having a pH of 7 and which is, therefore neither acid nor alkaline. In a less technical sense, a “neutral” cleaner has a pH between 6 and 8.

Neutralize
To eliminate potential hazards by inactivating strong acids, alkalis, caustics or oxidizers. For example, acid spills can be neutralized by adding an appropriate amount of caustic substance to the spill. A neutralizer is a chemical used to bring the pH of leather to approximately 4.

Normal Cleaning
Normal cleaning is the process of thorough cleaning using industry acceptable methods. It must be perform periodically, approximately every 12 to 24 months, depending on the furniture location, use, and exposure to soiling. Normal cleaning should be accomplished before soiling causes permanent damage to leather, dyes or finishing.

Nubuck
Top grain aniline dyed leather with a “suede-like” nap effect created by removing the top hair cell layer through a buffing process.

Nude Finish
Leather that is usually vat-dyed, but has little or no protective topcoat to prevent crocking or staining.

Offal
Offal refers to the part cut off, usually referring to the piece that falls off when a panel is cut to size. It also could refer to portions of hides or skins not normally used for making the finest grades of leather; not necessary waste. However, during the tanning process, offal are the excess edging of head, legs and tail parts that are trimmed off as waste to round up the hide.

Oil Tanned
Procedure of tanning that generally used fish oils. This produces very supple leathers.

Oleophilic
Literally “oil loving”. A reference to a material’s ability to attract oily substance.

Oleophobic
Literally “oil fearing”. A substrate that repels oily substances.

Oxidizing Bleach
An agent that removes color by adding oxygen to a dye structure rendering it colorless.

Patina
A surface luster that develops on pure anilines and nubuck, causing it to grow more beautiful with the passing of time.

Pelt
Describes any skin or hide that has gone through the tanning process. Also can describe any hide under 15 sq. ft. in size.

pH
The negative logarithm of the concentrations of Hydrogen Ions (H+) and Hydroxyl Ions (OH-), (parts, %) in a water-based solution; an indication of a solutions relative acidity or alkalinity. A pH of 7 is neutral. A pH above 7 indicates alkalinity (bases), and a pH below 7 indicates acidity.

Pigment Leather
Leather with a surface that is coated with pigment or other opaque solution. This process also covers imperfections on the leather’s surface.

Pigmented
Leather whose surface is coated with a material containing pigment or other opaque substances.

Preconditioner
A preparatory solution that is applied prior to soil removal activities incorporated in various cleaning methods. Preconditioners usually are built detergents whose application in the cleaning sequence allows sufficient “dwell time” for complete soil deflocculation to occur

Principles of Cleaning
Basic steps that cannot be overlooked if technically correct, aesthetically pleasing, professional results are to be accomplished. The principles of cleaning consist of: Dry Soil Removal (vacuuming); Soil Suspension (chemical action, temperature, agitation and time); Soil Extraction (towel absorption or wet vacuuming); Finishing (grooming of naps as required); Drying (promoting evaporation and dehumidification).

Principles of Spotting
Remove Excess Contaminant: (scoop, blot or use wet or dry vacuum extraction). Dissolve: (use solvent-based solution to dissolve oil-based contaminants or components of spot and water-based solution to dissolve water-soluble components). Suspend: (use solvent-based or water-based detergents to lubricate fibers and suspend insoluble components of spots or stains). Digest: (use enzyme digesters to reduce complex, long-chain amino acids (proteins) to simpler, soluble forms prior to removal). Chemically Change: (use oxidizing bleaches, or reducing agents to remove color added stains).

Pull-Up
Leather that derives its color from dyes, waxes and/or oils. When this leather is pulled, stretch or scratch, the oils and/or waxes dissipate and become lighter in those areas.

Pure Aniline
Leather that receives its only color from dyes and exhibits natural markings and characteristics.

Rawhide
Cattle hide that has been dehaired and limed, but not tanned.

Reducing Agent
In a reduction reaction, the reducing agent is the chemical or substance that: 1) combines with oxygen; 2) loses electron in the reaction. In the context of cleaning, reducing agent are used in spotting. Examples of reducing agents are d’Tannin-3.5 and d’Tarnish-1.3.

Residue
Any un-removed material that is left on a surface after cleaning.

Restorative Cleaning
Restorative or “salvage” cleaning is required when soiling has become severe and, by request of the consumer, the furnishing must be returned to a sanitary and improved condition. Restorative cleaning is not a normal cleaning process and typically is performed by technicians specially trained or skilled in restorative cleaning. Often, procedures that may go beyond those outlined in industry cleaning standard are used.

Sauvage
Sauvage is a two-tone fashion effect that adds depth and character to the leather.

Semi-Aniline
Leather receiving color from micro-pigments and a topcoat applied.

Simulated leather
A non-woven material with the appearance of leather. The base fabric may be knitted or woven, with a coating of PVC or nitrocellulose coating the surface. Simulated leather may be wet cleaned with little difficulty using mild detergents.

Simulated Suede
A luxurious woven, knitted or flocked fabric that is finished to resemble suede leather.

Skin
Skins of small animals, under 35 sq. ft. such as pigs, sheep, etc.

Soil
Any undesired substance that is deposited on, or that is foreign to, the leather. Soil results from environmental conditions (e.g. dust and particles, shed fibers, foods and oily substances).

Soil Extraction Principle
The third “principle” of cleaning in which suspension soils are physically removed from leather.

Soil Suspension Principle
The second cleaning principle that incorporates the four fundamentals of cleaning: chemical action, heat or temperature, agitation and time.

Solvent
A substance capable of dissolving or dispersing one or more other substances. The liquid component of a solution in which a substance is dissolved. The most common solvent is water.

Spew (spue)
A portion of the oily constituents of leather that comes to the grain surface in the form of white crystallized or dark gummy deposits.

Split
The under portion of a hide or skin that has been split into two or more layers. Split may be finished or embossed to simulate the full top-grain leather; however they do not possess the strength, durability or hand of top grain leather.

Spot
A foreign material adding substance or change in texture to a leather surface. The terms spot, stains and discoloration often are used interchangeably in a non-technical context.

Spotting
Using of specifically formulated agents and techniques to treat isolated spots and stains which do not respond to normal cleaning.

Stains
Stains may be left after removing of spots or the additional of color (without texture) to a surface. In a non-technical context, the term “stain” is often applied to discoloration, or color removal from surfaces, as well.

Suede
Textured leather with a soft feel resulting from the surface of the leather being “napped” or textured. Suede absorbs soil and oils and due to potential damage from water or dry solvent-based cleaners, may be difficult to clean with conventional non leather safe products.

Suede Finish
A finish produced by running the surface of leather on a carborundum or emery wheel to separate fibers to give it a nap. The grain side of leather may be suede-finished known as nubuck, but the process most often is applied to the flesh surface. The term “suede” when used alone, refers to the leather only.

Suede Splits
Leather produced form the flesh split, exhibits a velvet-like nap.

Surface Active Agent
A detergent or other material that reduces the surface tension of liquids, such as water, enabling uniform distribution of that cleaning solution among leathers for more efficient cleaning.

Surface Tension
A cohesive bond that exists between molecules of a substance.

Surfactant
A contraction for “surface active agent”. A surface active agent is used in detergents to make water “wet”, to cause lathering and, by itself, to accomplished light-duty cleaning.

Suspension
A colloidal distribution of an insoluble material in a liquid without forming a solution. A suspension is created when detergent action disperses and prevents re-deposition of soil on a surface, usually until the soil can be extracted (rinsed) or otherwise removed.

Tannin
A soluble. Complex phenolic substance (C13H11011) of plant origin used in tannin hides, in dyeing, in making ink and in medicine. Tannin stains are brownish coloration that responds well to reducing agents; commonly caused by wine, coffee, tea, etc.

Tanning
The chemical and mechanical process of converting raw hide into a stable non-perishable state

Tanning Agent
Modern tanning uses soluble chromium sulfate to preserve the leather. Synthetic tanning and natural materials (plants and wood bark) also may be used in certain combinations.

Tensile Strength
The breaking point of leather, The higher the tensile strength, the stronger the leather.

Top Grain
The top layer of a hide, after the splitting process, in which the hair and epidermis have been removed. The grain may be either natural or embossed.

Top Grain Snuffed
Upholstery leather of the same type as full top grain, except that the surface of the hide is lightly snuffed or sandpapered overall. Snuffing removes only the top of the hair follicles.

Transpiration
Natural process of leather which absorbs and release moisture.

Unfinished Leather
Normally defines as Aniline dyed, naked leathers with nothing being added to change or enhance the natural characteristics.

Upholstery Leather
Generally, leather used for furniture, airplane, bus and automotive “furniture” coverings. The staple raw material in the US consists of large or “spread” cattle hides, split at least once and, in many cases, two or three times. Top cut go into higher grade upholstery, and splits are used in lower grades.

Use-Dilution
The final concentration at which a product is applied to leather or surface during use.

Vacuuming
The act of removing soils or moisture from leather or fabric by means of mechanical suction combined with airflow.

Vegetable Tanning
A generic term that covers the process of making leather using tannins from bark, woods or other parts of plants and trees as distinguished from “mineral tanning”.

Water-Repellant Leather
Leather, which has been treated with any of several chemical compounds that inhibit absorption of external water.

Wet Blue
Chrome tanned leather turned light blue in color after tanning.

Wetting Agent
A material that reduces the surface tension of water and thus, more efficiently displaces the air within leather that might prevent the penetration of cleaning solutions.

Wicking
The upward flow of moisture. Wicking is a capillary effect dependent on the surface character of the leather.

Yellowing
Leather discoloration that arises from one of several possible sources. Potential sources include, but not limited to: dye loss, fume fading, general soiling, oily soiling, oxidizing bleaches, or alkaline over exposure.