Fritted glass is finely porous glass through which gas or liquid may pass. It is made by sintering together glass particles into a porous body; this porous glass body can be called a frit. Applications in laboratory glassware include use in fritted glass filter items, scrubbers, or spargers. Other laboratory applications of fritted glass include packing in chromatography columns and resin beds for special chemical synthesis. In a fritted glass filter, a disc or pane of fritted glass is used to filter out solid particles, precipitate, or residue from a fluid, similar to a piece of filter paper; the fluid can go through the pores in the fritted glass, but the frit will stop a solid from going through. A fritted filter is part of a glassware item, so fritted glass funnels and fritted glass crucibles are available. Laboratory scale spargers as well as scrubbers, gas-washing bottles are similar glassware items which may use a fritted glass piece fused to the tip of a gas-inlet tube; this fritted glass tip is placed inside the vessel with liquid inside during use such that the fritted tip is submerged in the liquid.
To maximize surface area contact of the gas to the liquid, a gas stream is blown into the vessel through the fritted glass tip so that it breaks up the gas into many tiny bubbles. The purpose of sparging is to saturate the enclosed liquid with the gas to displace another gaseous component; the purpose of a scrubber or gas-washing bottle is to scrub the gas such that the liquid absorbs one of the gaseous components to remove it from the gas stream purifying the gas stream. Because frits are made up of particles of glass that are bonded together by small contact areas, it is wise to avoid using them in alkaline conditions, as these can dissolve the glass to some extent; this is not a problem, as the amount dissolved is minute, but the minute bonds in a frit can be rotted away, causing the frit to fall apart over time. As such, consideration should be given to using frits in such solutions and they should be and rinsed when cleaning the glass with bases like potassium hydroxide
YouTube is an American video-sharing website headquartered in San Bruno, California. Three former PayPal employees—Chad Hurley, Steve Chen, Jawed Karim—created the service in February 2005. Google bought the site in November 2006 for US$1.65 billion. YouTube allows users to upload, rate, add to playlists, comment on videos, subscribe to other users, it offers a wide variety of corporate media videos. Available content includes video clips, TV show clips, music videos and documentary films, audio recordings, movie trailers, live streams, other content such as video blogging, short original videos, educational videos. Most of the content on YouTube is uploaded by individuals, but media corporations including CBS, the BBC, Hulu offer some of their material via YouTube as part of the YouTube partnership program. Unregistered users can only watch videos on the site, while registered users are permitted to upload an unlimited number of videos and add comments to videos. Videos deemed inappropriate are available only to registered users affirming themselves to be at least 18 years old.
YouTube and its creators earn advertising revenue from Google AdSense, a program which targets ads according to site content and audience. The vast majority of its videos are free to view, but there are exceptions, including subscription-based premium channels, film rentals, as well as YouTube Music and YouTube Premium, subscription services offering premium and ad-free music streaming, ad-free access to all content, including exclusive content commissioned from notable personalities; as of February 2017, there were more than 400 hours of content uploaded to YouTube each minute, one billion hours of content being watched on YouTube every day. As of August 2018, the website is ranked as the second-most popular site in the world, according to Alexa Internet. YouTube has faced criticism over aspects of its operations, including its handling of copyrighted content contained within uploaded videos, its recommendation algorithms perpetuating videos that promote conspiracy theories and falsehoods, hosting videos ostensibly targeting children but containing violent and/or sexually suggestive content involving popular characters, videos of minors attracting pedophilic activities in their comment sections, fluctuating policies on the types of content, eligible to be monetized with advertising.
YouTube was founded by Chad Hurley, Steve Chen, Jawed Karim, who were all early employees of PayPal. Hurley had studied design at Indiana University of Pennsylvania, Chen and Karim studied computer science together at the University of Illinois at Urbana–Champaign. According to a story, repeated in the media and Chen developed the idea for YouTube during the early months of 2005, after they had experienced difficulty sharing videos, shot at a dinner party at Chen's apartment in San Francisco. Karim did not attend the party and denied that it had occurred, but Chen commented that the idea that YouTube was founded after a dinner party "was very strengthened by marketing ideas around creating a story, digestible". Karim said the inspiration for YouTube first came from Janet Jackson's role in the 2004 Super Bowl incident, when her breast was exposed during her performance, from the 2004 Indian Ocean tsunami. Karim could not find video clips of either event online, which led to the idea of a video sharing site.
Hurley and Chen said that the original idea for YouTube was a video version of an online dating service, had been influenced by the website Hot or Not. Difficulty in finding enough dating videos led to a change of plans, with the site's founders deciding to accept uploads of any type of video. YouTube began as a venture capital-funded technology startup from an $11.5 million investment by Sequoia Capital and an $8 million investment from Artis Capital Management between November 2005 and April 2006. YouTube's early headquarters were situated above a pizzeria and Japanese restaurant in San Mateo, California; the domain name www.youtube.com was activated on February 14, 2005, the website was developed over the subsequent months. The first YouTube video, titled Me at the zoo, shows co-founder Jawed Karim at the San Diego Zoo; the video was uploaded on April 23, 2005, can still be viewed on the site. YouTube offered the public a beta test of the site in May 2005; the first video to reach one million views was a Nike advertisement featuring Ronaldinho in November 2005.
Following a $3.5 million investment from Sequoia Capital in November, the site launched on December 15, 2005, by which time the site was receiving 8 million views a day. The site grew and, in July 2006, the company announced that more than 65,000 new videos were being uploaded every day, that the site was receiving 100 million video views per day. According to data published by market research company comScore, YouTube is the dominant provider of online video in the United States, with a market share of around 43% and more than 14 billion views of videos in May 2010. In May 2011, 48 hours of new videos were uploaded to the site every minute, which increased to 60 hours every minute in January 2012, 100 hours every minute in May 2013, 300 hours every minute in November 2014, 400 hours every minute in February 2017; as of January 2012, the site had 800 million unique users a month. It is estimated that in 2007 YouTube consumed as much bandwidth as the entire Internet in 2000. According to third-party web analytics providers and SimilarWeb, YouTube is the second-most visited website in the world, as of December 2016.
A mosaic is a piece of art or image made from the assembling of small pieces of colored glass, stone, or other materials. It is used in decorative art or as interior decoration. Most mosaics are made of small, flat square, pieces of stone or glass of different colors, known as tesserae; some floor mosaics, are made of small rounded pieces of stone, called "pebble mosaics". Mosaics have a long history, starting in Mesopotamia in the 3rd millennium BC. Pebble mosaics were made in Tiryns in Mycenean Greece. Early Christian basilicas from the 4th century onwards were decorated with ceiling mosaics. Mosaic art flourished in the Byzantine Empire from the 6th to the 15th centuries. Mosaic fell out of fashion in the Renaissance, though artists like Raphael continued to practise the old technique. Roman and Byzantine influence led Jewish artists to decorate 5th and 6th century synagogues in the Middle East with floor mosaics. Mosaic was used on religious buildings and palaces in early Islamic art, including Islam's first great religious building, the Dome of the Rock in Jerusalem, the Umayyad Mosque in Damascus.
Mosaic went out of fashion in the Islamic world after the 8th century. Modern mosaics are made by professional artists, street artists, as a popular craft. Many materials other than traditional stone and ceramic tesserae may be employed, including shells and beads; the earliest known examples of mosaics made of different materials were found at a temple building in Abra and are dated to the second half of 3rd millennium BC. They consist of pieces of colored stones and ivory. Excavations at Susa and Chogha Zanbil show evidence of the first glazed tiles, dating from around 1500 BC. However, mosaic patterns were not used until the times of Roman influence. Bronze age pebble mosaics have been found at Tiryns. Mythological subjects, or scenes of hunting or other pursuits of the wealthy, were popular as the centrepieces of a larger geometric design, with emphasized borders. Pliny the Elder mentions the artist Sosus of Pergamon by name, describing his mosaics of the food left on a floor after a feast and of a group of doves drinking from a bowl.
Both of these themes were copied. Greek figural mosaics could have been copied or adapted paintings, a far more prestigious artform, the style was enthusiastically adopted by the Romans so that large floor mosaics enriched the floors of Hellenistic villas and Roman dwellings from Britain to Dura-Europos. Most recorded names of Roman mosaic workers are Greek, suggesting they dominated high quality work across the empire. Splendid mosaic floors are found in Roman villas across North Africa, in places such as Carthage, can still be seen in the extensive collection in Bardo Museum in Tunis, Tunisia. There were two main techniques in Greco-Roman mosaic: opus vermiculatum used tiny tesserae cubes of 4 millimeters or less, was produced in workshops in small panels which were transported to the site glued to some temporary support; the tiny tesserae allowed fine detail, an approach to the illusionism of painting. Small panels called emblemata were inserted into walls or as the highlights of larger floor-mosaics in coarser work.
The normal technique was opus tessellatum, using larger tesserae, laid on site. There was a distinct native Italian style using black on a white background, no doubt cheaper than coloured work. In Rome and his architects used mosaics to cover some surfaces of walls and ceilings in the Domus Aurea, built 64 AD, wall mosaics are found at Pompeii and neighbouring sites; however it seems that it was not until the Christian era that figural wall mosaics became a major form of artistic expression. The Roman church of Santa Costanza, which served as a mausoleum for one or more of the Imperial family, has both religious mosaic and decorative secular ceiling mosaics on a round vault, which represent the style of contemporary palace decoration; the mosaics of the Villa Romana del Casale near Piazza Armerina in Sicily are the largest collection of late Roman mosaics in situ in the world, are protected as a UNESCO World Heritage Site. The large villa rustica, owned by Emperor Maximian, was built in the early 4th century.
The mosaics were covered and protected for 700 years by a landslide that occurred in the 12th Century. The most important pieces are the Circus Scene, the 64m long Great Hunting Scene, the Little Hunt, the Labours of Hercules and the famous Bikini Girls, showing women undertaking a range of sporting activities in garments that resemble 20th Century bikinis; the peristyle, the imperial apartments and the thermae were decorated with ornamental and mythological mosaics. Other important examples of Roman mosaic art in Sicily were unearthed on the Piazza Vittoria in Palermo where two houses were discovered; the most important scenes there depicted are an Orpheus mosaic, Alexander the Great's Hunt and the Four Seasons. In 1913 the Zliten mosaic, a Roman mosaic famous for its many scenes from gladiatorial contests and everyday life, was discovered in the Libyan town of Zliten. In 2000 archaeologists working
A bead is a small, decorative object, formed in a variety of shapes and sizes of a material such as stone, shell, plastic, wood or pearl and with a small hole for threading or stringing. Beads range in size from under 1 millimetre to over 1 centimetre in diameter. A pair of beads made from Nassarius sea snail shells 100,000 years old, are thought to be the earliest known examples of jewellery. Beadwork is the craft of making things with beads. Beads can be woven together with specialized thread, strung onto thread or soft, flexible wire, or adhered to a surface. Beads can be divided into several types of overlapping categories based on different criteria such as the materials from which they are made, the process used in their manufacturing, the place or period of origin, the patterns on their surface, or their general shape. In some cases, such as millefiori and cloisonné beads, multiple categories may overlap in an interdependent fashion. Beads can be made of many different materials; the earliest beads were made of a variety of natural materials which, after they were gathered, could be drilled and shaped.
As humans became capable of obtaining and working with more difficult materials, those materials were added to the range of available substances. But nowadays synthetic materials were added. In modern manufacturing, the most common bead materials are wood, glass and stone. Beads are still made from many occurring materials, both organic and inorganic. However, some of these materials now undergo some extra processing beyond mere shaping and drilling such as color enhancement via dyes or irradiation; the natural organics include bone, horn, seeds, animal shell, wood. For most of human history pearls were the ultimate precious beads of natural origin because of their rarity. Amber and jet are of natural organic origin although both are the result of partial fossilization; the natural inorganics include various types of stones, ranging from gemstones to common minerals, metals. Of the latter, only a few precious metals occur in pure forms, but other purified base metals may as well be placed in this category along with certain occurring alloys such as electrum.
There are paper beads. The oldest-surviving synthetic materials used for beadmaking have been ceramics: pottery and glass. Beads were made from ancient alloys such as bronze and brass, but as those were more vulnerable to oxidation they have been less well-preserved at archaeological sites. Many different subtypes of glass are now used for beadmaking, some of which have their own component-specific names. Lead crystal beads have a high percentage of lead oxide in the glass formula, increasing the refractive index. Most of the other named glass types have their formulations and patterns inseparable from the manufacturing process. Small, fusible plastic beads can be placed on a solid plastic-backed peg array to form designs and melted together with a clothes iron. Fusible beads come in many colors and degrees of transparency/opacity, including varieties that glow in the dark or have internal glitter. Plastic toy beads, made by chopping plastic tubes into short pieces, were introduced in 1958 by Munkplast AB in Munka-Ljungby, under the brand Nabbi.
Known as Indian beads, they were sewn together to form ribbons. The pegboard for bead designs was invented in the early 1960s by Gunnar Knutsson in Vällingby, Sweden, as a therapy for elderly homes; the bead designs were used as trivets. When the beads were made of polyethylene, it became possible to fuse them with a flat iron. In 2005, Munkplast/Nabbi introduced the Photo Pearls software that converts digital photos to bead designs. Hama come in three sizes: mini and maxi. Perler beads come in two sizes called biggie. Pyssla beads only come in one size. Modern mass-produced beads are shaped by carving or casting, depending on the material and desired effect. In some cases, more specialized metalworking or glassworking techniques may be employed, or a combination of multiple techniques and materials may be used such as in cloisonné. Most glass beads are pressed glass, mass-produced by preparing a molten batch of glass of the desired color and pouring it into molds to form the desired shape; this is true of most plastic beads.
A smaller and more expensive subset of glass and lead crystal beads are cut into precise faceted shapes on an individual basis. This was once done by hand but has been taken over by precision machinery. "Fire-polished" faceted beads are a less expensive alternative to hand-cut faceted crystal. They derive their name from the second half of a two-part process: first, the glass batch is poured into round bead molds they are faceted with a grinding wheel; the faceted beads are poured onto a tray and reheated just long enough to melt the surface, "polishing" out any minor surface irregularities from the grinding wheel. There are several specialized glassworking techniques that create a distinctive appearance throughout the body of the resulting beads, which are primarily referred to by the glass type. If the glass b
Glass art refers to individual works of art that are or wholly made of glass. It ranges in size from monumental works and installation pieces, to wall hangings and windows, to works of art made in studios and factories, including glass jewelry and tableware; as a decorative and functional medium, glass was extensively developed in Assyria. Invented by the Phoenicians, was brought to the fore by the Romans. In the Middle Ages, the builders of the great Norman and Gothic cathedrals of Europe took the art of glass to new heights with the use of stained glass windows as a major architectural and decorative element. Glass from Murano, in the Venetian Lagoon, is the result of hundreds of years of refinement and invention. Murano is still held as the birthplace of modern glass art; the turn of the 19th century was the height of the old art glass movement while the factory glass blowers were being replaced by mechanical bottle blowing and continuous window glass. Great ateliers like Tiffany, Daum, Gallé, the Corning schools in upper New York state, Steuben Glass Works took glass art to new levels.
The first uses of glass were in other small pieces of jewelry and decoration. Beads and jewelry are still among the most common uses of glass in art, can be worked without a furnace, it became fashionable to wear functional jewelry with glass elements, such as pocketwatches and monocles. Starting in the late 20th century, glass couture refers to the creation of exclusive custom-fitted clothing made from sculpted glass; these are made to order for the body of the wearer. They are or made of glass with extreme attention to fit and flexibility; the result is delicate, not intended for regular use. Some of the earliest and most practical works of glass art were glass vessels. Goblets and pitchers were popular as glassblowing developed as an art form. Many early methods of etching and forming glass were honed on these vessels. For instance the millefiori technique dates back at least to Rome. More lead glass or crystal glass were used to make vessels that rang like a bell when struck. In the 20th century, mass-produced glass work including artistic glass vessels were sometimes known as factory glass.
Starting in the Middle Ages, glass became more produced, used for windows in buildings. Stained glass became common for windows in grand civic buildings; the invention of plate glass and the Bessemer process allowed for glass to be used in larger segments, to support more structural loads, to be produced at larger scales. A striking example of this was the Crystal Palace in 1851, one of the first buildings to use glass as a primary structural material. In the 20th century, glass became used for tables and shelves, for internal walls, for floors; some of the best known glass sculptures are statuesque or monumental structures such as the statues by Livio Seguso, or by Stanislav Libenský and Jaroslava Brychtová. Another example is René Roubícek's "Object" 1960, a blown and hot-worked piece of 52.2 cm shown at the "Design in an Age of Adversity" exhibition at the Corning Museum of Glass in 2005. A chiselled and bonded plate glass tower by Henry Richardson serves as the memorial to the Connecticut victims of the 9/11 terrorist attacks.
In the early 20th century, most glass production happened in factories. Individual glassblowers making their own personalized designs would do their work in those large shared buildings; the idea of "art glass", small decorative works made of art with designs or objects inside, flourished. Pieces produced in small production runs, such as the Lampwork figures of Stanislav Brychta, are called art glass. By the 1970s, there were good designs for smaller furnaces, in the United States this gave rise to the "studio glass" movement of glassblowers who blew their glass outside of factories in their own studios; this coincided with a move towards smaller production runs of particular styles. This movement spread to other parts of the world as well. Examples of 20th-century studio glass: There has been a massive explosion in the underground art scene revolving around functional glass art. Many people agree that Bob Snodgrass was the first to popularize glass smoking vessels as well as fume; as he traveled with the Grateful Dead he was able to share his techniques to many different people in many different communities before settling down in Oregon and creating the Eugene Glass School.
As time went on, more and more artists got involved with pipe making and with the introduction of social media the market exploded. Top artists such as Quave and Sagan are able to bring in upwards of one hundred thousand dollars per piece with the market only expanding as the prohibition on marijuana comes to an end. Combining many of the above techniques, but focusing on art represented in the glass rather than its shape, glass panels or walls can reach tremendous sizes; these may be hung from a ceiling. Large panels can be found for interior use. Dedicated lighting is part of the artwork. Techniques used include stained glass, frosting and gilding. An artist may combine techniques through silkscreening. Glass panels or walls may be complemented by running water or dynamic lights. Several of the most common techniques for producing glass art include: blowing, kiln-casting, slumping, pâté-de-verre, flame-working, hot-sculpting and cold-working. Cold work includes traditional stained glass work as well as other methods of
The Roman Empire was the post-Roman Republic period of the ancient Roman civilization. Ruled by emperors, it had large territorial holdings around the Mediterranean Sea in Europe, North Africa, the Middle East, the Caucasus. From the constitutional reforms of Augustus to the military anarchy of the third century, the Empire was a principate ruled from the city of Rome; the Roman Empire was ruled by multiple emperors and divided in a Western Roman Empire, based in Milan and Ravenna, an Eastern Roman Empire, based in Nicomedia and Constantinople. Rome remained the nominal capital of both parts until 476 AD, when Odoacer deposed Romulus Augustus after capturing Ravenna and the Roman Senate sent the imperial regalia to Constantinople; the fall of the Western Roman Empire to barbarian kings, along with the hellenization of the Eastern Roman Empire into the Byzantine Empire, is conventionally used to mark the end of Ancient Rome and the beginning of the Middle Ages. The previous Republic, which had replaced Rome's monarchy in the 6th century BC, became destabilized in a series of civil wars and political conflict.
In the mid-1st century BC Julius Caesar was appointed as perpetual dictator and assassinated in 44 BC. Civil wars and proscriptions continued, culminating in the victory of Octavian, Caesar's adopted son, over Mark Antony and Cleopatra at the Battle of Actium in 31 BC; the following year Octavian conquered Ptolemaic Egypt, ending the Hellenistic period that had begun with the conquests of Alexander the Great of Macedon in the 4th century BC. Octavian's power was unassailable and in 27 BC the Roman Senate formally granted him overarching power and the new title Augustus making him the first emperor; the first two centuries of the Empire were a period of unprecedented stability and prosperity known as the Pax Romana. It reached its greatest territorial expanse during the reign of Trajan. A period of increasing trouble and decline began with the reign of Commodus. In the 3rd century, the Empire underwent a crisis that threatened its existence, but was reunified under Aurelian. In an effort to stabilize the Empire, Diocletian set up two different imperial courts in the Greek East and Latin West.
Christians rose to power in the 4th century following the Edict of Milan in 313 and the Edict of Thessalonica in 380. Shortly after, the Migration Period involving large invasions by Germanic peoples and the Huns of Attila led to the decline of the Western Roman Empire. With the fall of Ravenna to the Germanic Herulians and the deposition of Romulus Augustulus in 476 AD by Odoacer, the Western Roman Empire collapsed and it was formally abolished by emperor Zeno in 480 AD; the Eastern Roman Empire, known in the post-Roman West as the Byzantine Empire, collapsed when Constantinople fell to the Ottoman Turks of Mehmed II in 1453. Due to the Roman Empire's vast extent and long endurance, the institutions and culture of Rome had a profound and lasting influence on the development of language, architecture, philosophy and forms of government in the territory it governed Europe; the Latin language of the Romans evolved into the Romance languages of the medieval and modern world, while Medieval Greek became the language of the Eastern Roman Empire.
Its adoption of Christianity led to the formation of Christendom during the Middle Ages. Greek and Roman art had a profound impact on the late medieval Italian Renaissance, while Rome's republican institutions influenced the political development of republics such as the United States and France; the corpus of Roman law has its descendants in many legal systems of the world today, such as the Napoleonic Code. Rome's architectural tradition served as the basis for Neoclassical architecture. Rome had begun expanding shortly after the founding of the republic in the 6th century BC, though it did not expand outside the Italian peninsula until the 3rd century BC, it was an "empire" long before it had an emperor. The Roman Republic was not a nation-state in the modern sense, but a network of towns left to rule themselves and provinces administered by military commanders, it was ruled, not by annually elected magistrates in conjunction with the senate. For various reasons, the 1st century BC was a time of political and military upheaval, which led to rule by emperors.
The consuls' military power rested in the Roman legal concept of imperium, which means "command". Successful consuls were given the honorary title imperator, this is the origin of the word emperor since this title was always bestowed to the early emperors upon their accession. Rome suffered a long series of internal conflicts and civil wars from the late second century BC onward, while extending its power beyond Italy; this was the period of the Crisis of the Roman Republic. Towards the end of this era, in 44 BC, Julius Caesar was perpetual dictator before being assassinated; the faction of his assassins was driven from Rome and defeated at the Battle of Philippi in 42 BC by an army led by Mark Antony and Caesar's adopted son Octavian. Antony and Octavian's division of the Roman world between themselves did not last and Octavian's forces defeated those of Mark Antony and Cleopatra at the Battle of Actium in 31 BC, ending the Final War of the Roman Republic. In 27 BC the Senate and People of Rome made Octavian princeps ("first citi
Polymer clay is a type of hardenable modeling clay based on the polymer polyvinyl chloride. It contains no clay minerals, but like mineral clay a liquid is added to dry particles until it achieves gel-like working properties, the part is put into an oven to harden, hence its colloquial designation as clay. Polymer clay is used for making arts and craft items, is used in commercial applications to make decorative parts. Art made from polymer clay can now be found in major museums. Bakelite, an early plastic, was popular with designers and was an early form of polymer clay, but the phenol base of uncured Bakelite was flammable and was discontinued. Polymer clays were first formulated as a possible replacement for Bakelite. One of these formulations was brought to the attention of German doll maker Käthe Kruse in 1939. While it was not suitable for use in her factory, Kruse gave some to her daughter Sophie, known in the family as "Fifi", who used it as modeling clay; the formulation was sold to Eberhard Faber and marketed under the name "FIMO".
Polymer clays contain a basis of a liquid plasticizer, making it a plastisol. Polymer clay plastisol is categorized as a plastigel because of its rheological properties, it is a high yield thixotropic material. This plasticity is what makes it useful as modeling clay as opposed to paste. Plastigels retain their shape when heat is applied, why polymer clay does not melt or droop when oven cured. Various gelling agents are added to give it this property such as aminated bentonite, metallic soaps, or fumed silica; the base resin can be modified in various ways. Mineral oil and odorless mineral spirits can be added to reduce its viscosity or alter its working properties. Small amounts of zinc oxide, kaolin, or other fillers are sometimes added to increase opacity, elastic modulus, or compression strength. Polymer clay is available in many colors, which can be mixed to create a wide range of colors or gradient blends. Special-effect colors and composites include translucent, fluorescent and faux "pearls", "metallics", "stone."
Polymer clay remains workable until cured generally. Curing occurs at temperatures from between 265 °F to 275 °F sustained for 15 minutes per 1⁄4 inch of thickness; this temperature is less than for mineral clays and can be achieved using a home oven. Professional clay brands shrink little when cured Brands of polymer clay include Fimo and Kato Polyclay. A home pasta-making machine is a popular multi-purpose tool for polymer clay artists, it is used to create sheets of uniform thickness, to mix colors or created variegated sheets, to condition the clay. Polymer clay needs to be conditioned prior to use; this involves kneading the clay by hand, passing it between two rollers, or using a low-shear mixer to break up any resin particle adhesions. Once conditioned, the clay will remain pliable until the particles re-adhere. Liquid polymer clay is a popular addition to polymer clay that can be used as a sort of “glue” to combine pieces, or to create different effects. Pigments, chalk pastel, regular polymer clay can be added in order to make colored liquid clay.
Liquid clay is hardened in an oven. Polymer clay safety is the subject of concern regarding the long-term effects of exposure to certain phthalate plasticizers that have been classified as endocrine disruptors; when used as a toy or child care item, it should not contain more than 0.1% of any of the six phthalates restricted or banned by the safety regulatory boards. These six phthalates are: DEHP, DBP, BBP, DINP, DIDP, DnOP (Di-n-octyl phthalate, according to the Consumer Product Safety Improvement Act. If the instructions on the package are followed one will not burn the clay. If the clay does burn because of a mistake or if the oven malfunctions, a small amount of hydrogen chloride gas could be released, which may cause odor and some eye or nose irritation; the amount of hydrogen chloride gas released from the clay could cause a health problem. Due to the testing requirements and regulations, clay products that would be used to hold or serve food or beverages are not recommended or intended for these applications.
All polymer clay products are NOT labeled as “food safe”. Plasticizers remain in the cured product and can leach out, making it a potential health hazard for both the modeler and end user. Restrictions on use of certain phthalates took effect in 2009 in both the European Union and United States. Not all phthalates pose a health hazard and some are approved for medical applications. Polymer clay can be used to make a variety of folk-crafts and jewelry. Air dry formulations, sometimes referred to as self-hardening polymer clay, contain no polymers