"scavenger agent, to treat water being fed to steam boilers to avoid corrosion problems, in the photographic industry to protect developer solutions from oxidation and (as hypo clear solution) to wash fixer (sodium thiosulfate) from film and photo-paper emulsions, in the textile industry as a bleaching, desulfurizing and dechlorinating agent and in the leather trade for the sulphonation of tanning extracts. It is used in the purification of TNT for military use. It is used in chemical manufacturing as a sulfonation and sulfomethylation agent. It is used in the production of sodium thiosulfate. It is used in other applications, including"
"salts, later developed by William Willis. Herschel coined the term ""photography"" in 1839. Herschel was also the first to apply the terms ""negative"" and ""positive"" to photography. He discovered sodium thiosulfate to be a solvent of silver halides in 1819, and informed Talbot and Daguerre of his discovery that this ""hyposulphite of soda"" (""hypo"") could be used as a photographic fixer, to ""fix"" pictures and make them permanent, after experimentally applying it thus in early 1839. His ground-breaking research on the subject was read at the Royal Society in London in March 1839 and January 1840. Herschel wrote many papers"
"ammonium thiosulfate—commonly used in modern rapid fixer formulae. Fixation involves these chemical reactions (X = halide, typically Br): Fixer is used for processing all commonly used films, including black-and-white films, Kodachrome, and chromogenic films. In chromogenic films, the remaining silver must be removed by a chemical mixture called a bleach fix, sometimes shortened to ""blix"". This mixture contains ammonium thiosulphate and ferrous EDTA, a powerful chelating agent. After fixation, washing is important to remove the exhausted chemicals from the emulsion. Otherwise they cause image deterioration. Other treatments of the remaining silver-based image are sometimes used to prevent ""burning"". Photographic fixer"
"Ammonium thiosulfate Ammonium thiosulfate (ammonium thiosulphate in British English) is an inorganic compound with the formula (NH)SO. It is white crystalline solid with ammonia odor, readily soluble in water, slightly soluble in acetone and insoluble in ethanol and diethyl ether. It is produced by treating ammonium sulfite with sulfur: Ammonium thiosulfate is used in photographic fixer. It is a so-called rapid fixer, acting more quickly than sodium thiosulfate fixers. Fixation involves these chemical reactions (illustrated for silver bromide): Ammonium thiosulfate is also used for leaching of gold and silver. It works with presence of copper as a catalyst here. This"
"least three times. This is not needed when non-hardening fixers are used. Over-washing can actually reduce the archival properties of film, as thiosulfate in very small concentrations has been shown to have a beneficial effect on film image stability. Washing (photography) In photography, washing is an important part of all film processing and printmaking processes. After materials have been fixed, washing removes unwanted and exhausted processing chemicals which, if left in situ, may cause deterioration and destruction of the image. A disadvantage of the use of thiosulfate as a fixer is its ability to dissolve elemental silver at a very"
"Thiosulfate Thiosulfate () (IUPAC-recommended spelling; sometimes thiosulphate in British English) is an oxyanion of sulfur. The prefix thio- indicates that the thiosulfate ion is a sulfate ion with one oxygen replaced by sulfur. Thiosulfate has a tetrahedral molecular shape with C symmetry. Thiosulfate occurs naturally and is produced by certain biochemical processes. It rapidly dechlorinates water and is notable for its use to halt bleaching in the paper-making industry. Thiosulfate is also useful in smelting silver ore, in producing leather goods, and to set dyes in textiles. Sodium thiosulfate, commonly called ""hypo"" (from ""hyposulfite""), was widely used in photography to"
"Washing (photography) In photography, washing is an important part of all film processing and printmaking processes. After materials have been fixed, washing removes unwanted and exhausted processing chemicals which, if left in situ, may cause deterioration and destruction of the image. A disadvantage of the use of thiosulfate as a fixer is its ability to dissolve elemental silver at a very slow rate. If films or papers are inadequately washed after fixing, any residual fixer can slowly bleach or stain the photographic image. For prints on high grade fibre papers, a period of continuous washing in clean, cold water for"
"making them relatively insensitive to additional exposure to light. In 1839, John Herschel pointed out his earlier published discovery that hyposulphite of soda (now known as sodium thiosulfate but still nicknamed ""hypo"") dissolved silver halides. This allowed the remaining light-sensitive silver salts to be completely washed away, truly ""fixing"" the photograph. Herschel also found that in the case of silver nitrate, a thorough washing with plain water sufficed to remove the unwanted remainder from paper—at least, the type of paper Herschel used—but only if the water was very pure. In 1885, Samuel Highley, an early photography historian, published an article"
"fix black and white negatives and prints after the developing stage; modern 'rapid' fixers use ammonium thiosulfate as a fixing salt because it acts three to four times faster. Some bacteria can metabolise thiosulfates. Thiosulfate is produced by the reaction of sulfite ion with elemental sulfur, and by incomplete oxidation of sulfides (pyrite oxidation), sodium thiosulfate can be formed by disproportionation of Sulfur dissolving in sodium hydroxide (similar to phosphorus). Thiosulfates are stable only in neutral or alkaline solutions, but not in acidic solutions, due to disproportionation to sulfite and sulfur, the sulfite being dehydrated to sulfur dioxide: This reaction"
"window in Lacock Abbey, one of a number of camera photographs he made in the summer of 1835, may be the oldest camera negative in existence. British chemist John Herschel made many contributions to the new field. He invented the cyanotype process, later familiar as the ""blueprint"". He was the first to use the terms ""photography"", ""negative"" and ""positive"". He had discovered in 1819 that sodium thiosulphate was a solvent of silver halides, and in 1839 he informed Talbot (and, indirectly, Daguerre) that it could be used to ""fix"" silver-halide-based photographs and make them completely light-fast. He made the first"
"a hair waving agent. Ammonium based hair products have been made to replace sodium hydroxide based products due to the destructive nature of sodium hydroxide on hair. The most common food product with ammonium sulfite is caramel coloring. According to the FDA, caramel coloring contains ammonium, potassium, or sodium sulfite. Ammonium sulfite is used as a preservative for fixers in photography. When film photographs are being developed ammonium sulfite can be one of the reducing agents used to preserve the hypo (Sodium or Ammonium Thiosulfate). Examples are given in Modern Photographic Processing, Volume I by Doctor Grant M. Haist of"
"is used to reduce the size of color dots without reducing their number, as a kind of manual color correction called dot etching. It is also used in black-and-white photography with sodium thiosulfate (hypo) to reduce the density of a negative or gelatin silver print where the mixture is known as Farmer's reducer; this can help offset problems from overexposure of the negative, or brighten the highlights in the print. The compound is also used to harden iron and steel, in electroplating, dyeing wool, as a laboratory reagent, and as a mild oxidizing agent in organic chemistry. Potassium ferricyanide is"
"synthesis of hydantoins, which can be useful synthetic intermediates, when reacted with a carbonyl compound such as an aldehyde or ketone in the presence of ammonium carbonate. KCN is used as a photographic fixer in the wet plate collodion process. The KCN dissolves silver where it has not been made insoluble by the developer. This reveals and stabilizes the image, making it no longer sensitive to light. Modern wet plate photographers may prefer less toxic fixers, often opting for the less toxic Sodium thiosulphate, but KCN is still used. In gold mining, KCN forms the water-soluble salt potassium gold cyanide"
"°C. The resulting visible image was then ""fixed"" (made insensitive to further exposure to light) by removing the unaffected silver iodide with concentrated and heated salt water. Later, a solution of the more effective ""hypo"" (hyposulphite of soda, now known as sodium thiosulfate) was used instead. The resultant plate produced an exact reproduction of the scene. The image was laterally reversed—as images in mirrors are—unless a mirror or inverting prism was used during exposure to flip the image. To be seen optimally, the image had to be lit at a certain angle and viewed so that the smooth parts of"
"The image as a whole therefore appeared to be a dull-toned positive. This ability to employ underexposed images allowed shorter exposure times to be used, a great advantage in portraiture. To obtain as light-toned an image as possible, potassium cyanide, a very dangerous and powerful deadly poison, was normally employed as the photographic fixer. It was perhaps the most acutely hazardous of all the several highly toxic chemicals originally used in this and many other early photographic processes. One unusual piece of tintype equipment was a twelve-lensed camera that could make a dozen ""gem"" portraits with one exposure, developed in"
"hyposulphite of soda to fix daguerreotype images, despite clear indications that he was aware of prior art demonstrated and published by Sir John Herschel. John Thomas Cooper John Thomas Cooper (1790–1854) was an English chemist notable as a lecturer, chemical supplier and chemical analyst, at a time when interest was burgeoning in chemistry as a discipline of study and application. Cooper was born in Greenwich and studied and for a short while practised medicine. Finding the life of general practitioner stressful and tiring, he turned instead to chemistry, to which he applied himself with zeal. Until 1842 he lectured in"
"its resistance to pitting (AISI 316L hMo). In alkaline aqueous conditions and medium temperature (60 °C), carbon steel and stainless steel (AISI 304L, 316L) are not attacked, even at high concentration of base (30%w KOH), thiosulfate (10%w) and in presence of fluoride ion (5%w KF). The natural occurrence of the thiosulfate group is practically restricted to a very rare mineral sidpietersite, Pb(SO)O(OH), as the presence of this anion in the mineral bazhenovite was recently disputed. Thiosulfate extensively forms complexes with transition metals hence a common use is dissolving silver halides in film photography developing. Thiosulfate is also used to extract"
"produce a white precipitate: Alkylation of sodium thiosulfate gives ""S""-alkylthiosulfates, which are called Bunte salts. The alkylthiosulfates are susceptible to hydrolysis, affording the thiol. This reaction is illustrated by one synthesis of thioglycolic acid: Sodium thiosulfate Sodium thiosulfate (sodium thiosulphate) is a chemical and medication. As a medication it is used to treat cyanide poisoning and pityriasis versicolor. It is an inorganic compound with the formula NaSOHO. Typically it is available as the white or colorless pentahydrate, NaSO·5HO. The solid is an efflorescent (loses water readily) crystalline substance that dissolves well in water. It is also called sodium hyposulfite or"
"or leach gold (sodium thiosulfate) and silver from their ores as a less toxic alternative to cyanide. Thiosulfate is an acceptable common name (but used almost always); functional replacement IUPAC name is sulfurothioate; the systematic additive IUPAC name is trioxidosulfidosulfate(2−) or trioxido-1""κ""""O""-disulfate(""S""—""S"")(2−). The external sulfur has an oxidation state of –2 (−II) while the central sulfur atom has an oxidation number of +6 (+VI). The enzyme rhodanase catalyzes the detoxification of cyanide by thiosulfate: CN + → SCN + . Sodium thiosulfate has been considered as an empirical treatment for cyanide poisoning, along with hydroxocobalamin. It is most effective in"
"form is a mild irritant and should be handled with gloves. Chronic overexposure can have adverse effects on the thyroid. Potassium iodide is a possible teratogen. KI is used with silver nitrate to make silver iodide (AgI), an important chemical in film photography. KI is a component in some disinfectants and hair treatment chemicals. KI is also used as a fluorescence quenching agent in biomedical research, an application that takes advantage of collisional quenching of fluorescent substances by the iodide ion. However, for several fluorophores addition of KI in µM-mM concentrations results in increase of fluorescence intensity, and iodide acts"
"(ZnS) is the inorganic pigment called lithopone. In photography it is used as a coating for certain photographic papers. A thin layer of barium sulfate called baryta is first coated on the base surface of most photographic paper to increase the reflectiveness of the image, with the first such paper introduced in 1884 in Germany. The light-sensitive silver halide emulsion is then coated over the baryta layer. The baryta coating limits the penetration of the emulsion into the fibers of the paper and makes the emulsion more even, resulting in more uniform blacks. (Further coatings may then be present for"
"the developer in a second bath. Once development is complete, the undeveloped silver salts must be removed by ""fixing"" in sodium thiosulphate or ammonium thiosulphate, and then the negative or print must be ""washed"" in clean water. The final image consists of metallic silver embedded in the gelatin coating. All gelatin silver photographic materials are subject to deterioration. The silver particles that comprise the image are susceptible to oxidation, leading to yellowing and fading of the image. Poor processing can also result in various forms of image degradation, due to residual silver-thiosulfate complexes. Toning increases the stability of the silver"
"is used as a tartar control agent in toothpastes. Disodium pyrophosphate Disodium pyrophosphate or sodium acid pyrophosphate (SAPP) is an inorganic compound consisting of sodium cations and pyrophosphate anion. It is a white, water-soluble solid that serves as a buffering and chelating agent, with many applications in the food industry. When crystallised from water, it forms a hexahydrate, but it dehydrates above room temperature. Pyrophosphate is a polyvalent anion with a high affinity for polyvalent cations, e.g. Ca. Disodium pyrophosphate is produced by heating sodium dihydrogen phosphate: Disodium pyrophosphate is a popular leavening agent found in baking powders. It combines"
"of any photographic print media will depend upon the processing, display and storage conditions of the print. Fixing must convert all non-image silver into soluble silver compounds that can be removed by washing with water. Washing must remove these compounds and all residual fixing chemicals from the emulsion and paper base. A hypo-clearing solution, also referred to as Hypo Clearing Agent, HCA, or a washing aid, and which can consist of a 2% solution of sodium sulfite, can be used to shorten the effective washing time by displacing the thiosulfate fixer, and the byproducts of the process of fixation, that"
"employed as a pigment to provide whiteness and opacity to products such as paints, coatings, plastics, papers, inks, foods, medicines (i.e. pills and tablets) as well as most toothpastes. In paint, it is often referred to offhandedly as ""brilliant white"", ""the perfect white"", ""the whitest white"", or other similar terms. Opacity is improved by optimal sizing of the titanium dioxide particles. When deposited as a thin film, its refractive index and colour make it an excellent reflective optical coating for dielectric mirrors; it is also used in generating decorative thin films such as found in ""mystic fire topaz"". Some grades"
"plastics and detergents. It is a radical scavenger that terminates radical polymerization reactions and serves as an antioxidant in natural rubber. (NHOH)SO is a starting material for some insecticides, herbicides and growth regulators. It is used in photography as a stabiliser for colour developers and as an additive in photographic emulsions in colour film. At 120 °C, hydroxylammonium sulfate begins to decompose to sulfur trioxide, nitrous oxide, water, and ammonia: The reaction is exothermic above 138 °C, and is most exothermic at 177 °C. Metals (especially copper, its alloys and its salts) catalyse the decomposition of hydroxylammonium sulfate. The instability"
"are used to bleach paper and to preserve dried fruit. Many surfactants and detergents (e.g. sodium lauryl sulfate) are sulfate derivatives. Calcium sulfate, gypsum, (CaSO·2HO) is mined on the scale of 100 million tonnes each year for use in Portland cement and fertilizers. When silver-based photography was widespread, sodium and ammonium thiosulfate were widely used as ""fixing agents."" Sulfur is a component of gunpowder (""black powder""). Sulfur is increasingly used as a component of fertilizers. The most important form of sulfur for fertilizer is the mineral calcium sulfate. Elemental sulfur is hydrophobic (not soluble in water) and cannot be used"
"Ammonium thiocyanate Ammonium thiocyanate is an inorganic compound with the formula NHSCN. It is the salt of the ammonium cation and the thiocyanate anion. Ammonium thiocyanate is used in the manufacture of herbicides, thiourea, and transparent artificial resins; in matches; as a stabilizing agent in photography; in various rustproofing compositions; as an adjuvant in textile dyeing and printing; as a tracer in oil fields; in the separation of hafnium from zirconium, and in titrimetric analyses. Ammonium thiocyanate can also be used to determine the iron content in soft drinks by colorimetry. Ammonium thiocyanate is made by the reaction of carbon"
"for movie projectors and search lights. Thorium tetrafluoride Thorium(IV) fluoride (ThF) is an inorganic chemical compound. It is a white, hygroscopic powder which can be produced by reacting thorium with fluorine gas. At temperatures above 500 °C, it reacts with atmospheric moisture to produce ThOF. Despite its (mild) radioactivity, thorium fluoride is used as an antireflection material in multilayered optical coatings. It has excellent optical transparency in the range 0.35–12 µm, and its radiation is primarily due to alpha particles, which can be easily stopped by a thin cover layer of another material. Thorium fluoride was used in manufacturing carbon"
"Society on 14 March to hear Sir John Herschel's seminal paper on photography in which Herschel proposed sodium hyposulfite as a fixer. Herschel also made some observations on the light sensitivity of silver carbonate, nitrate and acetate as being superior to silver chloride. Reade began experimenting with light-sensitive substances and soon discovered that he could get much better results when the silver salt was applied not to paper but to tanned leather. Allegedly, he used his wife's mittens for experiments. Reade conjectured that the difference in sensitivity was caused by gallic acid used for tanning, and indeed by treating paper"
"Caffenol Caffenol is a photographic alternative process whereby phenols, sodium carbonate and optionally Vitamin C are used in aqueous solution as a film and print photographic developer. Other basic (as opposed to acidic) chemicals can be used in place of sodium carbonate, however sodium carbonate is the most common. There are many formulas for caffenol. All are based on preparations which contain caffeic acid (i.e. coffee or tea) and a pH modifier, most often sodium carbonate. The chemistry of caffenol developers is based on the action of the reducing agent caffeic acid (which is chemically unrelated to caffeine). The Technical"
"known by the following names. Sodium lignosulfonate Sodium lignosulfonate (lignosulfonic acid, sodium salt) is used in the food industry as a de-foaming agent for paper production and in adhesives for items that come in contact with food. It has antimicrobial and preservative properties, and is used as an ingredient in animal feeds. It is also used for construction, ceramics, mineral powder, chemical industry, textile industry (leather), metallurgical industry, petroleum industry, fire-retardant materials, rubber vulcanization, organic polymerization. It is a pepsin inhibitor. Vovac, J.A. et al., Arch. Int. Pharmacodyn. Ther., 1969, 177, 150 (pharmacol) Alphin, R.S. et al., Experientia, 1972,28, 53"
"large amounts of illumination, to mixtures that were formerly used in photography. Because of the above-mentioned instability, the combination of aluminium powder and potassium chlorate is a poor choice for flash powder that is to be stored for more than a very short period. For that reason, it has been largely replaced by the potassium perchlorate mixtures. Chlorate mixes are used when cost is the overriding concern because potassium chlorate is less expensive than perchlorate. It is critically important to exclude sulfur and any acidic components from these mixtures. Sometimes a few percent of bicarbonate or carbonate buffer is added"