<unk>  is a popular strong base used in industry.<unk>  is used in the manufacture of<unk>  salts and detergents, pH regulation, and organic synthesis. In bulk, it is most often handled as an aqueous solution, since solutions are cheaper and easier to handle.<unk>  is used in many scenarios where it is desirable to increase the alkalinity of a mixture, or to neutralize acids. For example, in the petroleum industry,<unk>  is used as an additive in drilling mud to increase alkalinity in bentonite mud systems, to increase the mud viscosity, and to neutralize any acid gas (such as hydrogen sulfide and carbon dioxide) which may be encountered in the geological formation as drilling progresses. Another use is in Salt spray testing where pH needs to be regulated.<unk>  is used with hydrochloric acid to balance pH. The resultant salt, NaCl, is the corrosive agent used in the standard neutral pH salt spray test. Poor quality crude oil can be treated with<unk>  to remove sulfurous impurities in a process known as caustic washing. As above,<unk>  reacts with weak acids such as hydrogen sulfide and mercaptans to yield non-volatile<unk>  salts, which can be removed. The waste which is formed is toxic and difficult to deal with, and the process is banned in many countries because of this. In 2006, Trafigura used the process and then dumped the waste in Ivory Coast. Other common uses of<unk>  include: *for making soaps and detergents.<unk>  is used for hard bar soap while potassium<unk>  is used for liquid soaps.sodium<unk>  is used more often than potassium<unk>  because it is cheaper and a smaller quantity is needed. *as drain cleaners that contain<unk>  convert fats and grease that can clog pipes into soap, which dissolves in water. (see cleaning agent) *for making artificial textile fibres (such as Rayon). *in the manufacture of paper. Around 56% of<unk>  produced is used by industry, 25% of which is used in the paper industry. (see chemical pulping) *in purifying bauxite ore from which aluminium metal is extracted. This is known as Bayer process. (see dissolving amphoteric metals and compounds) *in de-greasing metals, oil refining, and making dyes and bleaches. *in water treatment plants for pH regulation. *to treat bagels and pretzel dough, giving the distinctive shiny finish. Chemical pulping<unk>  is also widely used in pulping of wood for making paper or regenerated fibers. Along with<unk>  sulfide,<unk>  is a key component of the white liquor solution used to separate lignin from cellulose fibers in the kraft process. It also plays a key role in several later stages of the process of bleaching the brown pulp resulting from the pulping process. These stages include oxygen delignification, oxidative extraction, and simple extraction, all of which require a strong alkaline environment with a pH > 10.5 at the end of the stages. Tissue digestion In a similar fashion,<unk>  is used to digest tissues, as in a process that was used with farm animals at one time. This process involved placing a carcass into a sealed chamber, then adding a mixture of<unk>  and water (which breaks the chemical bonds that keep the flesh intact). This eventually turns the body into a liquid with coffee-like appearance, and the only solid that remains are bone hulls, which could be crushed between one's fingertips.<unk>  is frequently used in the process of decomposing roadkill dumped in landfills by animal disposal contractors. Due to its availability and low cost, it has been used by criminals to dispose of corpses. Italian serial killer Leonarda Cianciulli used this chemical to turn dead bodies into soap. In Mexico, a man who worked for drug cartels admitted disposing of over 300 bodies with it.<unk>  is a dangerous chemical due to its ability to hydrolyze protein. If a dilute solution is spilled on the skin, burns may result if the area is not washed thoroughly and for several minutes with running water. Splashes in the eye can be more serious and can lead to blindness. Dissolving amphoteric metals and compounds Strong bases attack aluminium.<unk>  reacts with aluminium and water to release hydrogen gas. The aluminium takes the oxygen atom from<unk> , which in turn takes the oxygen atom from the water, and releases the two hydrogen atoms. The reaction thus produces hydrogen gas and<unk>  aluminate. In this reaction,<unk>  acts as an agent to make the solution alkaline, which aluminium can dissolve in. :<unk>  aluminate is an inorganic chemical that is used as an effective source of aluminium<unk>  for many industrial and technical applications. Pure<unk>  aluminate (anhydrous) is a white crystalline solid having a formula variously given as , , , or . Formation of<unk>  tetrahydroxoaluminate(III) or hydrated<unk>  aluminate is given by: : This reaction can be useful in etching, removing anodizing, or converting a polished surface to a satin-like finish, but without further passivation such as anodizing or alodining the surface may become degraded, either under normal use or in severe atmospheric conditions. In the Bayer process,<unk>  is used in the refining of alumina containing ores (bauxite) to produce alumina (aluminium oxide) which is the raw material used to produce aluminium metal via the electrolytic Hall-Héroult process. Since the alumina is amphoteric, it dissolves in the<unk> , leaving impurities less soluble at high pH such as iron oxides behind in the form of a highly alkaline red mud. Other amphoteric metals are zinc and lead which dissolve in concentrated<unk>  solutions to give<unk>  zincate and<unk>  plumbate respectively. Esterification and transesterification reagent<unk>  is traditionally used in soap making (cold process soap, saponification). It was made in the nineteenth century for a hard surface rather than liquid product because it was easier to store and transport. For the manufacture of biodiesel,<unk>  is used as a catalyst for the transesterification of methanol and triglycerides. This only works with anhydrous<unk> , because combined with water the fat would turn into soap, which would be tainted with methanol.<unk>  is used more often than potassium<unk>  because it is cheaper and a smaller quantity is needed. Due to production costs,<unk> , which is produced using common salt is cheaper than potassium<unk> . Food preparation Food uses of<unk>  include washing or chemical peeling of fruits and vegetables, chocolate and cocoa processing, caramel coloring production, poultry scalding, soft drink processing, and thickening ice cream. Olives are often soaked in<unk>  for softening; Pretzels and German lye rolls are glazed with a<unk>  solution before baking to make them crisp. Owing to the difficulty in obtaining food grade<unk>  in small quantities for home use,<unk>  carbonate is often used in place of<unk> . It is known as E number E524. Specific foods processed with<unk>  include: *German pretzels are poached in a boiling<unk>  carbonate solution or cold<unk>  solution before baking, which contributes to their unique crust. *Lye-water is an essential ingredient in the crust of the traditional baked Chinese moon cakes. *Most yellow coloured Chinese noodles are made with lye-water but are commonly mistaken for containing egg. *One variety of zongzi uses lye water to impart a sweet flavor.<unk>  is also the chemical that causes gelling of egg whites in the production of Century eggs. *Some methods of preparing olives involve subjecting them to a lye-based brine. *The Filipino dessert (kakanin) called kutsinta uses a small quantity of lye water to help give the rice flour batter a jelly like consistency. A similar process is also used in the kakanin known as pitsi-pitsi or pichi-pichi except that the mixture uses grated cassava instead of rice flour. *The Norwegian dish known as lutefisk (from lutfisk, "lye fish"). *Bagels are often boiled in a lye solution before baking, contributing to their shiny crust. *Hominy is dried maize (corn) kernels reconstituted by soaking in lye-water. These expand considerably in size and may be further processed by frying to make corn nuts or by drying and grinding to make grits. Hominy is used to create Masa, a popular flour used in Mexican cuisine to make Corn tortillas and tamales. Nixtamal is similar, but uses calcium<unk>  instead of<unk> . Cleaning agent<unk>  is frequently used as an industrial cleaning agent where it is often called "caustic". It is added to water, heated, and then used to clean process equipment, storage tanks, etc. It can dissolve grease, oils, fats and protein-based deposits. It is also used for cleaning waste discharge pipes under sinks and drains in domestic properties. Surfactants can be added to the<unk>  solution in order to stabilize dissolved substances and thus prevent redeposition. A<unk>  soak solution is used as a powerful degreaser on stainless steel and glass bakeware. It is also a common
Sodium hydroxide
Sodium hypochlorite
Amylmetacresol
Barium sulfate suspension
Silver nitrate
Chlorhexidine
Silver diammine fluoride
Perchloryl fluoride