Whitewash
Encyclopedia
Paint
Paint is any liquid, liquefiable, or mastic composition which after application to a substrate in a thin layer is converted to an opaque solid film. One may also consider the digital mimicry thereof...
made from slaked lime (calcium hydroxide) and chalk
Chalk
Chalk is a soft, white, porous sedimentary rock, a form of limestone composed of the mineral calcite. Calcite is calcium carbonate or CaCO3. It forms under reasonably deep marine conditions from the gradual accumulation of minute calcite plates shed from micro-organisms called coccolithophores....
(whiting). Various other additives are also used. The incident of Tom Sawyer
Tom Sawyer
Thomas "Tom" Sawyer is the title character of the Mark Twain novel The Adventures of Tom Sawyer . He appears in three other novels by Twain: Adventures of Huckleberry Finn , Tom Sawyer Abroad , and Tom Sawyer, Detective .Sawyer also appears in at least three unfinished Twain works, Huck and Tom...
whitewashing a fence as punishment is a famous image in American literature (written in 1876).
Whitewash
Whitewash cures through a reaction with carbon dioxideCarbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
in the atmosphere to form calcium carbonate
Calcium carbonate
Calcium carbonate is a chemical compound with the formula CaCO3. It is a common substance found in rocks in all parts of the world, and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural lime,...
in the form of calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
, a reaction known as carbonatation
Carbonatation
Carbonatation is a chemical reaction in which calcium hydroxide reacts with carbon dioxide and forms insoluble calcium carbonate:The process of forming a carbonate is sometimes referred to as "carbonation", although this term usually refers to the process of dissolving carbon dioxide in...
.
When the paint initially dries it is uncured and has almost no strength. It takes up to a few days, depending on climate, to harden.
It is usually applied to exteriors; however, it is traditionally used internally in food preparation areas, particularly rural dairies
Dairy
A dairy is a business enterprise established for the harvesting of animal milk—mostly from cows or goats, but also from buffalo, sheep, horses or camels —for human consumption. A dairy is typically located on a dedicated dairy farm or section of a multi-purpose farm that is concerned...
, for its mildly antibacterial properties. Occasionally it is coloured and used on structures such as the hallways of apartment buildings, but it is not popular for this as it can rub off onto clothing
Clothing
Clothing refers to any covering for the human body that is worn. The wearing of clothing is exclusively a human characteristic and is a feature of nearly all human societies...
to a small degree. In Britain and Ireland whitewash was used historically, both externally and internally, in workers' cottages, and still retains something of this association with rural poverty. In the United States, a similar attitude is expressed in the old saying: "Too proud to whitewash and too poor to paint", with the connotation that whitewash is a cheap imitation of "real" paint.
Whitewash is especially effective on adobe
Adobe
Adobe is a natural building material made from sand, clay, water, and some kind of fibrous or organic material , which the builders shape into bricks using frames and dry in the sun. Adobe buildings are similar to cob and mudbrick buildings. Adobe structures are extremely durable, and account for...
-like materials because it is absorbed easily and the resultant chemical reaction hardens the medium. Also, whitewash and adobe
Adobe
Adobe is a natural building material made from sand, clay, water, and some kind of fibrous or organic material , which the builders shape into bricks using frames and dry in the sun. Adobe buildings are similar to cob and mudbrick buildings. Adobe structures are extremely durable, and account for...
are both very low cost building materials.
Farming applications
Sun scald (flora)
Sun scald is the freezing of bark following high temperatures in the winter season, resulting in permanent visible damage to bark. Fruits may also be damaged.-Causes of Sun scald:...
. Some also claim that it helps prevent insect damage. Most often only the lower trunk is painted. In Poland painting the whole trunk is also said to help keep the body of the tree cool in late winter/ early spring months and hence help prevent fruit trees from blooming too soon i.e. when warm sunny days could promote rapid tree warming, rising sap and bloom and intermittent frosty nights could damage outer tree rings and destroy the young buds and blossoms.
In the middle of the 20th century, when family farms with dairy barns were common in the Upper Midwest
Upper Midwest
The Upper Midwest is a region in the northern portion of the U.S. Census Bureau's Midwestern United States. It is largely a sub-region of the midwest. Although there are no uniformly agreed-upon boundaries, the region is most commonly used to refer to the states of Minnesota, Wisconsin, and...
of the USA, whitewash was a necessary part of routine barn maintenance
Maintenance, Repair and Operations
Maintenance, repair, and operations or maintenance, repair, and overhaul involves fixing any sort of mechanical or electrical device should it become out of order or broken...
. A traditional animal barn contains a variety of extremely rough surfaces that are difficult to wash and keep clean, such as stone and brick masonry, and also rough-cut lumber for the ceiling. Left alone these surfaces collect dust, dirt, insect debris and wastes, and can become very dirty. Whitewash aids in sanitation by coating and smoothing over the rough surfaces. Successive applications of whitewash build up layers of scale which flake off and in the process remove surface debris with it. The coating also has antimicrobial properties that provide hygienic and sanitary benefits for animal barn
Barn
A barn is an agricultural building used for storage and as a covered workplace. It may sometimes be used to house livestock or to store farming vehicles and equipment...
s.
Typically the farm whitewash application is an annual process and has the following steps:
- Surfaces that are to be protected from whitewashing are enclosed in plastic sheeting or bags, such as windows, light fixtures, and the milk pipeline in a dairy barn.
- The interior is stripped of all removable equipment leaving walls, floors, and ceiling as bare as possible.
- A high volume compressed air wand (often supplied from a very large engine-driven air compressorAir compressorAn air compressor is a device that converts power into kinetic energy by compressing and pressurizing air, which, on command, can be released in quick bursts...
suitable for driving a jackhammerJackhammerA jackhammer is a pneumatic tool that combines a hammer directly with a chisel that was invented by Charles Brady King. Hand-held jackhammers are typically powered by compressed air, but some use electric motors. Larger jackhammers, such as rig mounted hammers used on construction machinery, are...
) is used to blast away loose whitewash scale from the walls and ceiling. This loose debris is swept into the barn gutter and goes into the manure handling system where it eventually contributes to soil fertility. - A mobile whitewashing trailer is used to mix the quicklime into a thick liquid, which is then sprayed as a thick even coating over the interior walls, ceiling, and posts, into all accessible nooks and crevasses.
- The coating is allowed a few hours to dry and stop dripping from the ceiling, and the protective plastic coverings are removed. Eventually after the walls and ceilings have dried sufficiently, equipment is brought back into the barn.
Nonremovable electric equipment is often enclosed in protective outer shells that prevent whitewash intrusion. For example circuit breaker
Circuit breaker
A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and, by interrupting continuity, to immediately discontinue electrical flow...
panels may be enclosed within wooden cabinetry which keeps the whitewash spray coating from entering the panel.
Limewash
Lime wash is pure slaked lime in water. It produces a unique surface glow due the to refractionRefraction
Refraction is the change in direction of a wave due to a change in its speed. It is essentially a surface phenomenon . The phenomenon is mainly in governance to the law of conservation of energy. The proper explanation would be that due to change of medium, the phase velocity of the wave is changed...
of calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
crystals. Limewash and whitewash both cure to become the same material.
When limewash is initially applied it has very low opacity
Opacity (optics)
Opacity is the measure of impenetrability to electromagnetic or other kinds of radiation, especially visible light. In radiative transfer, it describes the absorption and scattering of radiation in a medium, such as a plasma, dielectric, shielding material, glass, etc...
, which can lead novices to overthicken the paint. Drying increases opacity, and subsequent curing increases opacity again.
Additives
Additives that have been used include water glass, glueAnimal glue
An animal glue is an adhesive that is created by prolonged boiling of animal connective tissue.These protein colloid glues are formed through hydrolysis of the collagen from skins, bones, tendons, and other tissues, similar to gelatin. The word "collagen" itself derives from Greek κόλλα kolla, glue...
, 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...
, Portland cement
Portland cement
Portland cement is the most common type of cement in general use around the world because it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout...
, salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...
, soap
Soap
In chemistry, soap is a salt of a fatty acid.IUPAC. "" Compendium of Chemical Terminology, 2nd ed. . Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford . XML on-line corrected version: created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN...
, milk
Milk
Milk is a white liquid produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals before they are able to digest other types of food. Early-lactation milk contains colostrum, which carries the mother's antibodies to the baby and can reduce the risk of many...
, flour
Flour
Flour is a powder which is made by grinding cereal grains, other seeds or roots . It is the main ingredient of bread, which is a staple food for many cultures, making the availability of adequate supplies of flour a major economic and political issue at various times throughout history...
, soil
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
.
Whitewash is sometimes coloured with earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
s to achieve colours spanning the range of broken white
White
White is a color, the perception of which is evoked by light that stimulates all three types of color sensitive cone cells in the human eye in nearly equal amounts and with high brightness compared to the surroundings. A white visual stimulation will be void of hue and grayness.White light can be...
, cream
Cream (colour)
Cream is the colour of the cream produced by cattle grazing on natural pasture with plants rich in yellow carotenoid pigments, some of which are incorporated into the cream, to give a yellow tone to white. Cream is the pastel colour of yellow, much like as pink is to red. Cream is used as a skin...
, yellow
Yellow
Yellow is the color evoked by light that stimulates both the L and M cone cells of the retina about equally, with no significant stimulation of the S cone cells. Light with a wavelength of 570–590 nm is yellow, as is light with a suitable mixture of red and green...
and a range of brown
Brown
Brown is a color term, denoting a range of composite colors produced by a mixture of orange, red, rose, or yellow with black or gray. The term is from Old English brún, in origin for any dusky or dark shade of color....
s.
Historically pig's blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
was added to give the colour Suffolk pink, a colour still widely used on house exteriors in some areas of the UK. Animal blood also further reinforces the earth based medium to some degree.
Pozzolan
Pozzolan
A pozzolan is a material which, when combined with calcium hydroxide, exhibits cementitious properties. Pozzolans are commonly used as an addition to Portland cement concrete mixtures to increase the long-term strength and other material properties of Portland cement concrete, and in some cases...
ic materials are occasionally added to give a much harder wearing paint finish. This addition, however, creates a short open time, and therefore requires timely application of the altered paint.
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...
is sometimes added (typically 0.5-2%) to improve adhesion on difficult surfaces.
Cement
Cement
In the most general sense of the word, a cement is a binder, a substance that sets and hardens independently, and can bind other materials together. The word "cement" traces to the Romans, who used the term opus caementicium to describe masonry resembling modern concrete that was made from crushed...
addition makes a harder wearing paint in white
White
White is a color, the perception of which is evoked by light that stimulates all three types of color sensitive cone cells in the human eye in nearly equal amounts and with high brightness compared to the surroundings. A white visual stimulation will be void of hue and grayness.White light can be...
or grey
Grey
Grey or gray is an achromatic or neutral color.Complementary colors are defined to mix to grey, either additively or subtractively, and many color models place complements opposite each other in a color wheel. To produce grey in RGB displays, the R, G, and B primary light sources are combined in...
. Open time is short, so this is added at point of use. However, the use of cement restricts the breathable aspects of the limewash; Cement should not be applied to historic buildings in general.
Dilute glue
Glue
This is a list of various types of glue. Historically, the term "glue" only referred to protein colloids prepared from animal flesh. The meaning has been extended to refer to any fluid adhesive....
s improve paint toughness.
Wheat flour
Wheat flour
Wheat flour is a powder made from the grinding of wheat used for human consumption. More wheat flour is produced than any other flour. Wheat varieties are called "clean," "white," or "brown" if they have high gluten content, and they are called "soft" or "weak" flour if gluten content is low...
has been used as a strength enhancing binder. Salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...
is usually added to prevent the flour going mouldy later in damp
Moisture
Humidity is the amount of moisture the air can hold before it rains. Moisture refers to the presence of a liquid, especially water, often in trace amounts...
conditions. The use of salt brings its own issues, such as deterioration of brick and stone.
Cost
Simple lime paints are very low cost. A 25 kg bag of lime makes around 100 kg of paint, and costs around £6 in the UK (2008).External links
- Farm recipe for whitewash, with details
- Lighthouse keeperLighthouse keeperA lighthouse keeper is the person responsible for tending and caring for a lighthouse, particularly the light and lens in the days when oil lamps and clockwork mechanisms were used. Keepers were needed to trim the wicks, replenish fuel, wind clockworks and perform maintenance tasks such as cleaning...
's formula for White Wash at Crisp Point Light.