Lute (material)
Encyclopedia
Lute was a substance used to seal
and affix apparatus employed in chemistry
and alchemy
, and to protect component vessels against heat damage by fire; it was also used to line furnace
s. Lutation was thus the act of "cementing vessels with lute".
, which required airtight vessels and connectors to ensure that no vapours were lost; thus it was employed by chemists and alchemists
, the latter being known to refer to it as "lutum sapientiae" or the "lute of Wisdom".
The earthen and glass vessels commonly employed in these processes were very vulnerable to cracking, both on heating and on cooling; one way of protecting them was by coating the vessels with lute and allowing it to set. One mixture for this purpose included "fat earth" (terra pinguis), Windsor loam
, sand, iron filings
or powdered glass
, and cow's hair.
Another use for lute was to act as a safety valve
, preventing the build up of vapour pressure from shattering a vessel and possibly causing an explosion. For this purpose, a hole was bored in the flask and covered with luting material of a particular composition, which was kept soft so that excessive build up of vapour would cause it to come away from the vessel, thus releasing the pressure safely. This process could also be performed manually by the operator removing and reaffixing the lute as required. Lute was also used to effect repairs to cracked glass vessels.
Lute was frequently applied to the joints between vessels (such as retorts
and receivers), making them airtight and preventing vapour from escaping; this was especially important for more penetrating "spiritous" vapours and required a mixture that would set hard - such as a mix of quicklime and either egg white
or size
etc. However a stronger lute had to be used to confine acid vapours, and for this purpose fat earth and linseed oil
were mixed to form "fat lute", which could be rolled into cylinders of convenient size, ready for use. Where the vapour was more "aqueous", and less penetrating, strips of paper affixed with sizing
would suffice or "bladder long steeped in water".
Another related use for lute was for lining furnaces, and was described as far back as the 16th century by Georg Agricola
in his "De re metallica
".
mixed with oil and beaten until it had the consistency of putty
. It could be stored in a sealed earthenware
vessel, which retained moisture and kept the material pliable. An alchemical writer of the 16th century recommended a lute made up of "loam mixed to a compost with horse dung
" while the French chemist Chaptal
used a similar mixture of "fat earth" and horse dung, mixed in water and formed into a soft paste.
Linseed meal or Almond meal
could be made into a lute by mixing with water or dissolved starch
or weak glue, and used in combination with strips of rag
or moistened bladder
; however, it was combustible which limited its range of applications.
Lime
could be made into an effective lute by mixing it with egg white or glue; for sealing joints it was used in conjunction with strips of rag.
Linen
rags mixed with paste, or strips of Bladder soaked in warm water, then coated with paste or egg white, also served as a lute.
Fire Lute was used to protect vessels from heat damage. It consisted of clay mixed with sand and either horse-hair
or straw
or tow (coarse, broken fibre of crops such as flax
, hemp
, or jute
). It had to be allowed to dry thoroughly before use to be effective.
Fusible lute was used to coat earthenware vessels to ensure impermeability. A mixture of Borax
and slaked lime, mixed with water into a fine paste, served this purpose.
Parker's Cement
, Plaster of Paris and Fusible fluxes (a clay and Borax mixture in 10:1 proportion, mixed to a paste in water) could all be used as lutes, rendering heat protection and air-tightness. Stourbridge
clay mixed with water could withstand the highest heat of any lute.
Hard cement was also commonly used to join glass vessels and fix cracks; it was composed of resin
, beeswax
and either brick dust or "bole earth", or red ochre or venetian red
. Soft cement, made of yellow wax
, turpentine
and venetian red, was also used for repair.
Sealant
A sealant may be viscous material that has little or no flow characteristics and stay where they are applied or thin and runny so as to allow it to penetrate the substrate by means of capillary reaction...
and affix apparatus employed in chemistry
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....
and alchemy
Alchemy
Alchemy is an influential philosophical tradition whose early practitioners’ claims to profound powers were known from antiquity. The defining objectives of alchemy are varied; these include the creation of the fabled philosopher's stone possessing powers including the capability of turning base...
, and to protect component vessels against heat damage by fire; it was also used to line furnace
Furnace
A furnace is a device used for heating. The name derives from Latin fornax, oven.In American English and Canadian English, the term furnace on its own is generally used to describe household heating systems based on a central furnace , and sometimes as a synonym for kiln, a device used in the...
s. Lutation was thus the act of "cementing vessels with lute".
Uses
Lute was commonly used in distillationDistillation
Distillation is a method of separating mixtures based on differences in volatilities of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....
, which required airtight vessels and connectors to ensure that no vapours were lost; thus it was employed by chemists and alchemists
Alchemy
Alchemy is an influential philosophical tradition whose early practitioners’ claims to profound powers were known from antiquity. The defining objectives of alchemy are varied; these include the creation of the fabled philosopher's stone possessing powers including the capability of turning base...
, the latter being known to refer to it as "lutum sapientiae" or the "lute of Wisdom".
The earthen and glass vessels commonly employed in these processes were very vulnerable to cracking, both on heating and on cooling; one way of protecting them was by coating the vessels with lute and allowing it to set. One mixture for this purpose included "fat earth" (terra pinguis), Windsor loam
Loam
Loam is soil composed of sand, silt, and clay in relatively even concentration . Loam soils generally contain more nutrients and humus than sandy soils, have better infiltration and drainage than silty soils, and are easier to till than clay soils...
, sand, iron filings
Iron filings
Iron filings are very small pieces of iron that look like a light powder. They are very often used in science demonstrations to show the direction of a magnetic field. Since iron is a ferromagnetic material, a magnetic field induces each particle to become a tiny bar magnet...
or powdered glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
, and cow's hair.
Another use for lute was to act as a safety valve
Safety valve
A safety valve is a valve mechanism for the automatic release of a substance from a boiler, pressure vessel, or other system when the pressure or temperature exceeds preset limits....
, preventing the build up of vapour pressure from shattering a vessel and possibly causing an explosion. For this purpose, a hole was bored in the flask and covered with luting material of a particular composition, which was kept soft so that excessive build up of vapour would cause it to come away from the vessel, thus releasing the pressure safely. This process could also be performed manually by the operator removing and reaffixing the lute as required. Lute was also used to effect repairs to cracked glass vessels.
Lute was frequently applied to the joints between vessels (such as retorts
Retort
In a chemistry laboratory, a retort is a glassware device used for distillation or dry distillation of substances. It consists of a spherical vessel with a long downward-pointing neck. The liquid to be distilled is placed in the vessel and heated...
and receivers), making them airtight and preventing vapour from escaping; this was especially important for more penetrating "spiritous" vapours and required a mixture that would set hard - such as a mix of quicklime and either egg white
Egg white
Egg white is the common name for the clear liquid contained within an egg. In chickens it is formed from the layers of secretions of the anterior section of the hen's oviduct during the passage of the egg. It forms around either fertilized or unfertilized egg yolks...
or size
Sizing
Sizing or size is any one of numerous specific substances that is applied to or incorporated in other material, especially papers and textiles, to act as a protecting filler or glaze....
etc. However a stronger lute had to be used to confine acid vapours, and for this purpose fat earth and linseed oil
Linseed oil
Linseed oil, also known as flaxseed oil, is a clear to yellowish oil obtained from the dried ripe seeds of the flax plant . The oil is obtained by cold pressing, sometimes followed by solvent extraction...
were mixed to form "fat lute", which could be rolled into cylinders of convenient size, ready for use. Where the vapour was more "aqueous", and less penetrating, strips of paper affixed with sizing
Sizing
Sizing or size is any one of numerous specific substances that is applied to or incorporated in other material, especially papers and textiles, to act as a protecting filler or glaze....
would suffice or "bladder long steeped in water".
Another related use for lute was for lining furnaces, and was described as far back as the 16th century by Georg Agricola
Georg Agricola
Georgius Agricola was a German scholar and scientist. Known as "the father of mineralogy", he was born at Glauchau in Saxony. His real name was Georg Pawer; Agricola is the Latinised version of his name, Pawer meaning "farmer"...
in his "De re metallica
De re metallica
De re metallica is a book cataloguing the state of the art of mining, refining, and smelting metals, published in 1556. The author was Georg Bauer, whose pen name was the Latinized Georgius Agricola...
".
Composition
Fat Lute was made of ClayClay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
mixed with oil and beaten until it had the consistency of putty
Putty
Putty is a generic term for a plastic material similar in texture to clay or dough typically used in domestic construction and repair as a sealant or filler. Painter's Putty is typically a linseed oil based product used for filling holes, minor cracks and defacements in wood only...
. It could be stored in a sealed earthenware
Earthenware
Earthenware is a common ceramic material, which is used extensively for pottery tableware and decorative objects.-Types of earthenware:Although body formulations vary between countries and even between individual makers, a generic composition is 25% ball clay, 28% kaolin, 32% quartz, and 15%...
vessel, which retained moisture and kept the material pliable. An alchemical writer of the 16th century recommended a lute made up of "loam mixed to a compost with horse dung
Manure
Manure is organic matter used as organic fertilizer in agriculture. Manures contribute to the fertility of the soil by adding organic matter and nutrients, such as nitrogen, that are trapped by bacteria in the soil...
" while the French chemist Chaptal
Jean-Antoine Chaptal
Jean-Antoine Claude, comte Chaptal de Chanteloup was a French chemist and statesman. He established chemical works for the manufacture of the mineral acids, soda and other substances...
used a similar mixture of "fat earth" and horse dung, mixed in water and formed into a soft paste.
Linseed meal or Almond meal
Almond meal
Almond meal, almond flour or ground almond is made from ground sweet almonds. Almond flour is usually made with blanched almonds , whereas almond meal can be made both with whole or blanched almonds...
could be made into a lute by mixing with water or dissolved starch
Wheatpaste
Wheatpaste is a liquid adhesive made from vegetable starch and water. It has been used since ancient times for various arts and crafts such as book binding, decoupage, collage, and papier-mâché...
or weak glue, and used in combination with strips of rag
Textile
A textile or cloth is a flexible woven material consisting of a network of natural or artificial fibres often referred to as thread or yarn. Yarn is produced by spinning raw fibres of wool, flax, cotton, or other material to produce long strands...
or moistened bladder
Pig bladder
Pig bladder is the bladder of a domestic pig, similar to the human urinary bladder. Today, this hollow organ has various applications in medicine, and in traditional cuisines and customs...
; however, it was combustible which limited its range of applications.
Lime
Calcium hydroxide
Calcium hydroxide, traditionally called slaked lime, is an inorganic compound with the chemical formula Ca2. It is a colourless crystal or white powder and is obtained when calcium oxide is mixed, or "slaked" with water. It has many names including hydrated lime, builders lime, slack lime, cal, or...
could be made into an effective lute by mixing it with egg white or glue; for sealing joints it was used in conjunction with strips of rag.
Linen
Linen
Linen is a textile made from the fibers of the flax plant, Linum usitatissimum. Linen is labor-intensive to manufacture, but when it is made into garments, it is valued for its exceptional coolness and freshness in hot weather....
rags mixed with paste, or strips of Bladder soaked in warm water, then coated with paste or egg white, also served as a lute.
Fire Lute was used to protect vessels from heat damage. It consisted of clay mixed with sand and either horse-hair
Horsehair
Horsehair is the long, coarse hair growing on the manes and tails of horses. It is used for various purposes, including upholstery, brushes, the bows of musical instruments, a hard-wearing fabric called haircloth, and for horsehair plaster, a wallcovering material formerly used in the construction...
or straw
Straw
Straw is an agricultural by-product, the dry stalks of cereal plants, after the grain and chaff have been removed. Straw makes up about half of the yield of cereal crops such as barley, oats, rice, rye and wheat. It has many uses, including fuel, livestock bedding and fodder, thatching and...
or tow (coarse, broken fibre of crops such as flax
Flax
Flax is a member of the genus Linum in the family Linaceae. It is native to the region extending from the eastern Mediterranean to India and was probably first domesticated in the Fertile Crescent...
, hemp
Hemp
Hemp is mostly used as a name for low tetrahydrocannabinol strains of the plant Cannabis sativa, of fiber and/or oilseed varieties. In modern times, hemp has been used for industrial purposes including paper, textiles, biodegradable plastics, construction, health food and fuel with modest...
, or jute
Jute
Jute is a long, soft, shiny vegetable fibre that can be spun into coarse, strong threads. It is produced from plants in the genus Corchorus, which has been classified in the family Tiliaceae, or more recently in Malvaceae....
). It had to be allowed to dry thoroughly before use to be effective.
Fusible lute was used to coat earthenware vessels to ensure impermeability. A mixture of Borax
Borax
Borax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is an important boron compound, a mineral, and a salt of boric acid. It is usually a white powder consisting of soft colorless crystals that dissolve easily in water.Borax has a wide variety of uses...
and slaked lime, mixed with water into a fine paste, served this purpose.
Parker's Cement
James Parker (cement maker)
James Parker was a British clergyman and cement manufacturer who invented one of the pioneering new cements of the late eighteenth century.In 1791, he was granted a patent "Method of Burning bricks, Tiles, Chalk"...
, Plaster of Paris and Fusible fluxes (a clay and Borax mixture in 10:1 proportion, mixed to a paste in water) could all be used as lutes, rendering heat protection and air-tightness. Stourbridge
Stourbridge
Stourbridge is a town within the Metropolitan Borough of Dudley, in the West Midlands of England. Historically part of Worcestershire, Stourbridge was a centre of glass making, and today includes the suburbs of Amblecote, Lye, Norton, Oldswinford, Pedmore, Wollaston, Wollescote and Wordsley The...
clay mixed with water could withstand the highest heat of any lute.
Hard cement was also commonly used to join glass vessels and fix cracks; it was composed of resin
Resin
Resin in the most specific use of the term is a hydrocarbon secretion of many plants, particularly coniferous trees. Resins are valued for their chemical properties and associated uses, such as the production of varnishes, adhesives, and food glazing agents; as an important source of raw materials...
, beeswax
Beeswax
Beeswax is a natural wax produced in the bee hive of honey bees of the genus Apis. It is mainly esters of fatty acids and various long chain alcohols...
and either brick dust or "bole earth", or red ochre or venetian red
Venetian red
Venetian red is a light and warm pigment that is a darker shade of scarlet, derived from nearly pure ferric oxide of the hematite type. Modern versions are frequently made with synthetic red iron oxide.-Venetian red:...
. Soft cement, made of yellow wax
Beeswax
Beeswax is a natural wax produced in the bee hive of honey bees of the genus Apis. It is mainly esters of fatty acids and various long chain alcohols...
, turpentine
Turpentine
Turpentine is a fluid obtained by the distillation of resin obtained from trees, mainly pine trees. It is composed of terpenes, mainly the monoterpenes alpha-pinene and beta-pinene...
and venetian red, was also used for repair.
Further reading
- Antoine-Laurent Lavoisier. Elements of chemistry etc. (Courier Dover Publications, 1790) ch. 7, "Of the composition and application of lutes".
- Samuel Frederick Gray & Arthur Livermore Porter. The chemistry of the arts etc. (Carey & Lea, 1830) p. 217 ff., "Chemical lutes".