Latex is a natural polymer derived from the sap of trees mainly in the Asclepiadaceae family. The Havea Brasiliensis, of Brazil is the largest latex producing plant in the world. Natural latex circulates in the branches, trunks, and other tissues of these trees, acting as an excretory system. The primary product produced from latex is rubber. Water is its base solvent. Latex is easily damaged by many different oils, ozone, and UV light. Liquid latex is a combination of water, latex sap, and ammonia. Liquid latex has many uses in the theater, toy industry, and cosmetics industry.
The base of liquid latex is natural latex. Records of natural latex use dates back to the early Mayan and Haitian civilizations. Europeans were first introduced to latex when Columbus came to the Americas in 1492 and discovered the residents of Haiti playing with a rubber ball and coating their clothing with latex. In 1770, English chemist Joseph Priestly coined the name ÒrubberÓ when he took a small ball of coagulated latex and Òrubbed offÓ pencil markings. During this time period large scale ÒtappingÓ of the latex-producing trees was put into use. The tapping process involves cutting a slit in the bark of a rubber-producing tree, allowing the latex to drip into a collection container.
>From any one slit as much as four pounds of latex can be collected. The most important discovery concerning latex occurred when Charles Goodyear mixed sulfur dust and latex, discovering vulcanization. This vulcanization process is still used today. Vulcanized rubber is more resistant to temperature fluctuations than natural latex.
Liquid latex has many uses. It is used for theater props including masks and gloves. The manufacture of gloves and latex clothing items involves dipping, dripping, or painting the object, mold, or body to be covered with latex. The latex holds to porous surfaces, making non-porous surfaces perfect molds. Medical professionals also use liquid latex molded products like gloves. Other products using liquid latex include toys, puppet heads, masks, imitation pottery, clothing, hoses, coatings for rain gear and diving gear, and hot water bottles. According to Bob Kelly, of Bob Kelly Cosmetics Inc., liquid latex can be poured onto ones skin, treated with powder, and then removed to create instant wrinkles. This is one of the more unique uses of the substance.
Most form of liquid latex are a mixture of natural latex and other products. Natural latex is a polymer of the monomer isoprene with the chemical formula:{CH2 :C(CH3 )CH:CH2}. Small concentrations of pigments and oils are often added to the crude latex. Before the crude latex is mixed with anything it goes through a masticating machine that called a Gordon Plasticator that heats and churns the hard latex into soft material. Closed cylinder mixers are then used to mix the pure latex with ammonia and water. Typical liquid latex contains 34.7% natural latex, 65% water, and .3% ammonia. Ammonia is added to the natural latex as a preservative, retaining a high pH level and preserving the latex in its liquid form. Liquid latex is prevulcanized and air-cures at room temperature. Since the ammonia is present in such a low concentration, it vents quickly. Therefore, if the latex container is not properly sealed, it will begin to air-cure in the bottle. At higher temperatures, the latex cures more rapidly because the ammonia is released at a faster rate. To increase the flexibility of cured latex, fillers or other fibers can be placed in a mold with the latex. Liquid latex can be dyed and diluted.
Currently, synthetic latex products are also being produced. Around World War I, scientists tried to create a synthetic latex by polymerizing dimethylbutadiene, but this was unsuccessful. In 1930, Carothers and Straudinger discovered that polymers consist of many monomers and are long and chainlike, so synthetic rubber could be produced out of monomers other that just isoprene. Not long after this study a synthetic rubber polymer was created from a monomer of isoprene. Different synthetic latex products include: neoprene, buna rubbers, and butyl rubber.