Cadmium is a chemical element; it has symbol Cd and atomic number 48. This soft, silvery-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Like zinc, it demonstrates oxidation state +2 in most of its compounds, and like mercury, it has a lower melting point than the transition metals in groups 3 through 11. Cadmium and its congeners in group 12 are often not considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states. The average concentration of cadmium in Earth's crust is between 0.1 and 0.5 parts per million (ppm). It was discovered in 1817 simultaneously by Stromeyer and Hermann, both in Germany, as an impurity in zinc carbonate.
Paint is a liquid pigment that, after applied to a solid material and allowed to dry, adds a film-like layer, in most cases to create an image, known as a painting. Paint can be made in many colors and types. Most paints are either oil-based or water-based, and each has distinct characteristics.
A pigment is a powder used to add color or change visual appearance. Pigments are completely or nearly insoluble and chemically unreactive in water or another medium; in contrast, dyes are colored substances which are soluble or go into solution at some stage in their use. Dyes are often organic compounds whereas pigments are often inorganic. Pigments of prehistoric and historic value include ochre, charcoal, and lapis lazuli.
Gesso, also known as "glue gesso" or "Italian gesso", is a white paint mixture used to coat rigid surfaces such as wooden painting panels or masonite as a permanent absorbent primer substrate for painting. It consists of a binder mixed with chalk, gypsum, pigment, or any combination of these.
Toxic waste is any unwanted material in all forms that can cause harm. Mostly generated by industry, consumer products like televisions, computers, and phones contain toxic chemicals that can pollute the air and contaminate soil and water. Disposing of such waste is a major public health issue.
Titanium dioxide, also known as titanium(IV) oxide or titania, is the inorganic compound with the chemical formula TiO
2. When used as a pigment, it is called titanium white, Pigment White 6 (PW6), or CI 77891. It is a white solid that is insoluble in water, although mineral forms can appear black. As a pigment, it has a wide range of applications, including paint, sunscreen, and food coloring. When used as a food coloring, it has E number E171. World production in 2014 exceeded 9 million tonnes. It has been estimated that titanium dioxide is used in two-thirds of all pigments, and pigments based on the oxide have been valued at a price of $13.2 billion.
Saponification is a process of cleaving esters into carboxylate salts and alcohols by the action of aqueous alkali. Typically aqueous sodium hydroxide solutions are used. When the carboxylate is long chain, its salt is called a soap. The saponification of ethyl acetate gives sodium acetate and ethanol:
Cadmium pigments are a class of pigments that contain cadmium. Most of the cadmium produced worldwide has been for use in rechargeable nickel–cadmium batteries, which have been replaced by other rechargeable nickel-chemistry cell varieties such as NiMH cells, but about half of the remaining consumption of cadmium, which is approximately 2,000 tonnes annually, is used to produce colored cadmium pigments. The principal pigments are a family of yellow, orange and red cadmium sulfides and sulfoselenides, as well as compounds with other metals.
Oil paint is a type of slow-drying paint that consists of particles of pigment suspended in a drying oil, commonly linseed oil. The viscosity of the paint may be modified by the addition of a solvent such as turpentine or white spirit, and varnish may be added to increase the glossiness of the dried oil paint film. The addition of oil or alkyd medium can also be used to modify the viscosity and drying time of oil paint. Oil paints were first used in Asia as early as the 7th century AD and can be seen in examples of Buddhist paintings in Afghanistan. Oil-based paints made their way to Europe by the 12th century and were used for simple decoration, but oil painting did not begin to be adopted as an artistic medium there until the early 15th century. Common modern applications of oil paint are in finishing and protection of wood in buildings and exposed metal structures such as ships and bridges. Its hard-wearing properties and luminous colors make it desirable for both interior and exterior use on wood and metal. Due to its slow-drying properties, it has recently been used in paint-on-glass animation. The thickness of the coat has considerable bearing on the time required for drying: thin coats of oil paint dry relatively quickly.
Zinc white is an inorganic pigment composed of zinc oxide that has been used by painters since the late eighteenth century. Alongside lead and titanium white, it is among the three most prominent white pigments that are commercially available today. Its primary advantages are its low toxicity and the cool clarity of its color. It was initially developed in the 1780s by the French chemist and magistrate Louis-Bernard Guyton de Morveau, who struggled to popularize its use. The French Academy of Sciences approved of the invention in 1782, but artists from the French Royal Academy of Painting and Sculpture expressed skepticism. Initially, zinc white pigment was more costly to produce than lead white, but its price diminished as production methods improved over the course of the nineteenth century. While the superior safety of zinc white had been established by the end of the eighteenth century, manufacturers of lead white downplayed these differences, and lead continued to dominate the market for white paint until the early twentieth century.
White lead is the basic lead carbonate 2PbCO3·Pb(OH)2. It is a complex salt, containing both carbonate and hydroxide ions. White lead occurs naturally as a mineral, in which context it is known as hydrocerussite, a hydrate of cerussite. It was formerly used as an ingredient for lead paint and a cosmetic called Venetian ceruse, because of its opacity and the satiny smooth mixture it made with dryable oils. However, it tended to cause lead poisoning, and its use has been banned in most countries.
Fateful Harvest: The True Story of a Small Town, a Global Industry, and a Toxic Secret is a nonfiction book written by Duff Wilson, who was a reporter for the Seattle Times. The book began as a series of newspaper reports, which made the issue a "national focus".
Lead-based paint was widely used in the United States because of its durability. The United States banned the manufacture of lead-based house paint in 1978 due to health concerns.
The environmental effects of paint can vary depending on the type of paint used and mitigation measures. Traditional painting materials and processes can have harmful effects on the environment, including those from the use of lead and other additives. Measures can be taken to reduce its environmental effects, including accurately estimating paint quantities so waste is minimized, and use of environmentally preferred paints, coating, painting accessories, and techniques.
Most lead-based paint in the United Kingdom were banned from sale to the general public in 1992, except for specialist uses. Prior to this, lead compounds had been used as the pigment and drying agent in different types of paint, for example brick and some tile paints. Lead-based paint has been an important cause of lead poisoning.
British Titan Products was the manufacturer of Tioxide, a brand of white yet opaque pigment and whitening agent made from titanium dioxide. It was initially organised to replace titanium dioxide supplies that British paint manufacturers imported from Germany. This British industry was established as a joint venture in 1934 by two of the world's major mining and chemical businesses in conjunction with a major industrial consumer and a distribution business.
Lead contamination in Oakland represents a serious and persistent public health threat. Lead contamination in modern Oakland comes from three primary sources: remnants from previous industry, deposits from leaded gasoline, and paint chips from leaded paints. Significant portions of the City of Oakland, California have soil lead levels far in excess of 400 ppm, the level at which the US EPA suggests remedial action be taken, and far higher than 80 ppm, the level at which California’s Office of Environmental Health Hazard Assessment suggests action should be taken. Not all areas of Oakland are affected equally: West Oakland's contamination is especially severe, particularly near the former Oakland Army Base, and many of Oakland's poorer neighborhoods also suffer disproportionately.
Thermoplastic road marking paint, also called hot melt marking paint, is a kind of powder paint. When applied as road surface markings, a hot melt kettle is used to heat it to 200 °C (392 °F) to melt the powder, after which it is sprayed on the road surface. After cooling, the paint forms a thick polymer layer, which is wear-resistant, bright, and reflective. In recent years, practical applications tests have proved that the marking lines lack surface roughness and can easily cause wheel slip, resulting in a traffic accident in snow and rainy weather. Therefore, some countries once restricted the use of this paint or demand the use of anti-skid particles. In order to increase the antiskid performance of the line, thermoplastic paint has added reflective glass beads and other coarse fillers. Thermoplastic can be used very effectively for large anti-skid areas on roads and pedestrian walkways by adding glass beads. It can be produced in any colour and is suitable for car parks, factory walkways, and many other areas. It hardens quickly and can be driven over after just a few minutes.
Lead abatement is an activity to reduce levels of lead, particularly in the home environment, generally to permanently eliminate lead-based paint hazards, in order to reduce or eliminate incidents of lead poisoning.
