Rosin, (also called 'colophony' or 'Greek pitch') is a solid form of resin. It is got from pines and some other plants, mostly conifers. Heating fresh liquid resin vaporizes light volatiles like terpenes.
Rosin is semi-transparent and yellow to black in colour. The term "colophony" comes from "colophonia resina" or "resin from the pine trees of Colophon", an ancient Ionic city.
Rosin has hundreds of uses, of which only a few can be mentioned here. These uses fall into groups, such as:
Varnish
Varnish is a transparent, hard, protective finish or film primarily used in wood finishing but also for other materials. Varnish is traditionally a combination of a drying oil, a resin, and a solvent.
Most resin or "gum" varnishes are made of a natural substance dissolved in a solvent. The two main types of natural varnishes are "spirit varnish" (which uses alcohol as a solvent) and turpentine or petroleum-based varnish. Some resins are soluble in both alcohol and turpentine.
Shellac is a very widely used single component resin varnish that is dissolved in alcohol. It is not used outdoors or where it will touch water several times, such as around a sink or bathtub. insects in South Asia make it.
Secretion
Secretion is the process of releasing chemicals from a cell, or from a gland.
Eukaryotic cells have a highly evolved process of secretion.
Adhesive
An adhesive is a compound that sticks or bonds two items together. Adhesives may come from either natural or man-made material. Some modern adhesives are extremely strong, and are becoming increasingly important in modern construction and industry. Examples of adhesives include adhesive tape, glue, and sticky-tac. Some adhesives are for temporary use, like sticky-tac or the adhesive on sticky notes. Others are for more permanent bonding of small items like gluing paper or building large pieces of furniture using construction adhesive.
The first adhesives were natural gums and other plant resins. Archaeologists have found 6000-year-old ceramic vessels that had broken and been repaired using plant resin.
The earliest known use of adhesives was discovered in central Italy when two stone flakes partially covered with birch-bark tar. This is thought to be the oldest discovered human use of adhesives.
In Europe, glue was not used until the 1500–1700s. At this time, cabinet and furniture makers such as Thomas Chippendale and Duncan Phyfe started to use adhesives to hold their products together. In 1690, the first commercial glue plant was established in The Netherlands. This plant produced glues from animal hides. In 1750, the first British glue patent was issued for fish glue. In the 1800s, casein glues were invented and made in German and Swiss factories. In 1876, the first US patent was issued to the Ross brothers for the production of casein glue.
In 1910, a thermoset plastic known as Bakelite phenolic was made. In 1912, phenolic resin was applied to plywood as a coating varnish.
In 1920s–1940s, there was great advances in the development and production of new plastics and resins because of the First and Second World Wars.
Adhesives are usually classified by the method of adhesion. These are then classified into reactive and non-reactive adhesives, which refers to whether the adhesive chemically reacts in order to harden. They can also be classified by whether it is made from natural, or synthetic materials.
There are two types of adhesives that harden by drying. They are solvent-based adhesives and polymer dispersion adhesives. They are also known as emulsion adhesives. Solvent-based adhesives are a mixture of ingredients (usually polymers) dissolved in a solvent. White glue, contact adhesives and rubber cements are drying adhesives. As the solvent evaporates, the adhesive hardens.
A polymer based adhesive is a milky white coloured mixture that is based on polyvinyl acetate (PVA). They are used in the woodworking and packaging industries. They are also used with fabrics and and in engineered products such as loudspeakers.
"Pressure-sensitive adhesives" (PSA) stick to materials when pressure is applied. The bond forms because the adhesive is soft enough to flow to the adherend. The bond is very strong because the adhesive is hard enough to resist flow.
PSAs are made for either permanent or removable applications. Examples of permanent applications include safety label for power equipment, foil tape for HVAC duct work.
Removable adhesives are made to form a temporary bond, and can be removed after months or years without leaving residue on the adherend. Removable adhesives are used in applications such as surface protection films, masking tapes, bookmark and note papers, barcode labels and price marking labels.
Contact adhesives are used in strong bonds with high shear-resistance like laminates, such as bonding Formica to a wooden counter, and in footwear. Natural rubber and polychloroprene (Neoprene) are commonly used as contact adhesives.
Contact adhesives must be applied to both surfaces. It must be allowed some time to dry. Once the surfaces are pushed together, the bond forms very quickly.
Hot adhesives, are thermoplastics applied in melted form which turns into a solid when it cools to form strong bonds between. Ethylene-vinyl acetate-based hot-melts are mainly used for crafts.
Anaerobic adhesives hardens when in comes in contact with metal, in the absence of oxygen.
"Multi-component adhesives" harden by mixing two or more chemical which react together.
There are several commercial combinations of multi-component adhesives in use in industry. Some of these combinations are:
Gum
A number of different things are called "gum":
"See also:" GUM
Natural gum
Natural gums are polysaccharides of natural origin, that can change the viscosity of a material in solution, even at small concentrations.
Mineralization
Mineralization may mean:
Ali
Ali ibn Abi Talib (‘Alī ibn Abī Tālib) () (Approximately March 17, 599- January 28, 661) was an early Islamic leader. He was the fourth Sunni caliph and the first Shia imam.
The Prophet, Mohammad, took him as his brother in the pact of brotherhood in Medina, and he is said to be the first to accept Mohammed's teaching of Islam.
Zakarid Armenia
The Zakarid Armenia describes territories of Armenia given to the Zakarid-Mxargrzeli princes as a fief by Tamar, the queen of the Kingdom of Georgia.
Women and Islam
The complex relationship between women and Islam is shown by both Islamic texts and the history and culture of the Muslim world. Islamic scholars maintain that the Qur'an, the holy book of Islam, affirms women's religious and moral equality.
However, sharia (Islamic law) shows the marked differences between women's and men's roles, rights, and obligations, and many Muslim-majority countries give women different rights than men with regard to marriage, divorce, civil rights, legal status, dress code, and education.
Islamic feminism is a type of feminism that focuses on women in Islam. Nawal El Saadawi is an Egyptian feminist who has written many books about women in Islam.
Chador
A chador (Persian چادر) is a piece of clothing. It is for Muslim women. In Iran, women wear a chador in public. The Chador covers all the body except the face. However some religious women, cover their faces with their chador too.
A chador is a full-length semi-circle of fabric open down the front. It is thrown over the head and held shut in front. A chador has no hand openings or closures but is held shut by the hands or by wrapping the ends around the waist.
Vortex mixer
A vortex mixer is small machine used in laboratories to mix small beakers of liquids.