Polymer clay

Last updated December 24, 2024

Polymer clay is a type of hardenable modeling clay based on the polymer polyvinyl chloride (PVC). It typically contains no clay minerals, but like mineral clay a liquid is added to dry particles until it achieves gel-like working properties. Similarly, the part is put into an oven to harden, hence its colloquial designation as clay.^[1] Polymer clay is generally used for making arts and craft items, and is also used in commercial applications to make decorative parts. Art made from polymer clay can now be found in major museums.^[2]

History

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 eventually 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, who was known in the family as "Fifi", who successfully used it as modeling clay. The formulation was later sold to Eberhard Faber and marketed under the name "FIMO" (FIfi's MOdeling compound).^[3]

Composition

Polymer clays contain a basis of PVC resin and a liquid plasticizer,^[4] making it a plastisol. Polymer clay plastisol is also categorized as a plastigel because of its rheological properties.^[5] It is a high yield thixotropic material: when a sufficient force is applied, the material yields, flowing like a viscous liquid until that force is removed, whereupon it returns to being a solid. This plasticity is what makes it useful as modeling clay as opposed to putty or paste. Plastigels retain their shape even when heat is applied, which is why polymer clay does not melt or droop when oven cured.^[5] Various gelling agents are added to give it this property, such as aminated bentonite, metallic soaps, or fumed silica.^[6]

The base resin can be modified in various ways. Mineral oil, lecithin, 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, phosphorescent, and faux "pearls", "metallics", and "stone."

Use

Polymer clay remains workable until cured. Curing occurs at temperatures from 265 °F (129 °C) to 275 °F (135 °C) sustained for 15 minutes per 1⁄4 inch (6.4 mm) of thickness.^[1] This temperature is significantly less than for mineral clays and can be achieved using a home oven. Professional polymer clay brands shrink very little when cured^[7] Brands of polymer clay include Cernit, Oytra, Fimo, Kato Polyclay, Sculpey, PVClay Brasil, Crafty Argentina and Cosclay.

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 create variegated sheets, and to condition (soften) the clay.^[1] Polymer clay generally needs to be conditioned before 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 eventually re-adhere.^[8]

Oven-hardenable PVC plastisol, "liquid polymer clay," is a complement to polymer clay that can be used as an adhesive to combine pieces, or to create various effects. Pigments, chalk pastel, and regular polymer clay can be added to make colored liquid clay. The liquid can also be poured into molds to produce cast parts. ^{[ citation needed ]}

Health and safety

Polymer clay safety is the subject of concern specifically regarding the long-term effects of exposure to certain phthalate plasticizers that have been classified as endocrine disruptors.^[9] When used as a toy or child care item, in the United States, it should not contain more than 0.1% of any of the six phthalates restricted or banned by the safety regulatory board according to the Consumer Product Safety Improvement Act (CPSIA). These six phthalates are: DEHP (Di-2-ethylhexyl phthalate), DBP (Dibutyl phthalate), BBP (Benzyl butyl phthalate), DINP (Di-isononyl phthalate), DIDP (Di-isodecyl phthalate), and DnOP (Di-n-octyl phthalate). If the instructions on the package are followed (i.e. low temperatures and brief baking times) 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.^[10]

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. 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.^[11] Not all phthalates pose a health hazard and some are approved for medical applications.^[12]

Related Research Articles

Bakelite, formally polyoxybenzylmethyleneglycolanhydride, is a thermosetting phenol formaldehyde resin, formed from a condensation reaction of phenol with formaldehyde. The first plastic made from synthetic components, it was developed by a Belgian, Leo Baekeland in Yonkers, New York, in 1907, and patented on December 7, 1909.He beat his Scottish rival, James Swinburne, to the patent office by one day.

Polyvinyl chloride (alternatively: poly(vinyl chloride), colloquial: vinyl or polyvinyl; abbreviated: PVC) is the world's third-most widely produced synthetic polymer of plastic (after polyethylene and polypropylene). About 40 million tons of PVC are produced each year.

<span class="mw-page-title-main">Thermoplastic</span> Plastic that softens with heat and hardens on cooling

A thermoplastic, or thermosofteningplastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling.

Epoxy is the family of basic components or cured end products of epoxy resins. Epoxy resins, also known as polyepoxides, are a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide functional group is also collectively called epoxy. The IUPAC name for an epoxide group is an oxirane.

In materials science, a thermosetting polymer, often called a thermoset, is a polymer that is obtained by irreversibly hardening ("curing") a soft solid or viscous liquid prepolymer (resin). Curing is induced by heat or suitable radiation and may be promoted by high pressure or mixing with a catalyst. Heat is not necessarily applied externally, and is often generated by the reaction of the resin with a curing agent. Curing results in chemical reactions that create extensive cross-linking between polymer chains to produce an infusible and insoluble polymer network.

<span class="mw-page-title-main">Phthalates</span> Any ester derived from phthalic acid

Phthalates ( ), or phthalate esters, are esters of phthalic acid. They are mainly used as plasticizers, i.e., substances added to plastics to increase their flexibility, transparency, durability, and longevity. They are used primarily to soften polyvinyl chloride (PVC). While phthalates are commonly used as plasticizers, not all plasticizers are phthalates. The two terms are specific, unique, and not used interchangeably.

<span class="mw-page-title-main">Polyacrylamide</span> Chemical compound

Polyacrylamide (abbreviated as PAM or pAAM) is a polymer with the formula (-CH₂CHCONH₂-). It has a linear-chain structure. PAM is highly water-absorbent, forming a soft gel when hydrated. In 2008, an estimated 750,000,000 kg were produced, mainly for water treatment and the paper and mineral industries.

Fimo is a brand of polymer clay made by German company Staedtler. Fimo is sold worldwide. Its main U.S. competitor is the American brand Sculpey. The material comes in many different colors; there are many finishes to choose from, and even a softener to use with it because it can be hard to work. It is used for making many objects, including jewelry, accessories, and small ornaments. Once shaped, Fimo is baked in a standard or toaster oven for about 30 minutes at 130 °C (265 °F) to harden it. Once baked, it can be cut, drilled, painted, sanded, and sliced thinly. According to information from Staedtler, Fimo contains polyvinyl chloride (PVC), but has not contained any phthalates since 2006.

A plasticizer is a substance that is added to a material to make it softer and more flexible, to increase its plasticity, to decrease its viscosity, and/or to decrease friction during its handling in manufacture.

Nail polish is a lacquer that can be applied to the human fingernails or toenails to decorate and protect the nail plates. The formula has been revised repeatedly to enhance its decorative properties, to be safer for the consumer to use, and to suppress cracking or peeling. Nail polish consists of a mix of an organic polymer and several other components that give it colors and textures. Nail polishes come in all color shades and play a significant part in manicures and pedicures.

Sculpey is the brand name for a type of polymer clay that can be modeled and put into a conventional oven to harden, as opposed to typical modeling clays, which require a much hotter oven, such as a kiln. Until it is baked, Sculpey has a consistency somewhat like Plasticine. Its main competitor is the German brand Fimo. It is sold in many colors, but can also be painted once it’s baked. Sculpey has become popular with modeling artists, jewellery makers, and other craft work.

Powder coating is a type of coating that is applied as a free-flowing, dry powder. Unlike conventional liquid paint, which is delivered via an evaporating solvent, powder coating is typically applied electrostatically and then cured under heat or with ultraviolet light. The powder may be a thermoplastic or a thermosetting polymer. It is usually used to create a thick, tough finish that is more durable than conventional paint. Powder coating is mainly used for coating of metal objects, particularly those subject to rough use. Advancements in powder coating technology like UV-curable powder coatings allow for other materials such as plastics, composites, carbon fiber, and medium-density fibreboard (MDF) to be powder coated, as little heat or oven dwell time is required to process them.

Synthetic resins are industrially produced resins, typically viscous substances that convert into rigid polymers by the process of curing. In order to undergo curing, resins typically contain reactive end groups, such as acrylates or epoxides. Some synthetic resins have properties similar to natural plant resins, but many do not.

Curing is a chemical process employed in polymer chemistry and process engineering that produces the toughening or hardening of a polymer material by cross-linking of polymer chains. Even if it is strongly associated with the production of thermosetting polymers, the term "curing" can be used for all the processes where a solid product is obtained from a liquid solution, such as with PVC plastisols.

Kato polyclay is a brand of oven-hardening polymer clay. The concept of Kato Polyclay was created by the collaboration of Donna Kato, a polymer clay artist, and Van Aken International, a manufacturer of modeling compounds. The material is intended for decorative use such as jewelry, dolls, boxes or vases.

<span class="mw-page-title-main">Plastic bottle</span> Narrow-necked container

A plastic bottle is a bottle constructed from high-density or low density plastic. Plastic bottles are typically used to store liquids such as water, soft drinks, motor oil, cooking oil, medicine, shampoo or milk. They range in sizes, from very small bottles to large carboys. Consumer blow molded containers often have integral handles or are shaped to facilitate grasping.

<span class="mw-page-title-main">Plastisol</span> Suspension of polymer particles in a liquid plasticizer

A plastisol is a colloidal dispersion of small polymer particles, usually polyvinyl chloride (PVC), in a liquid plasticizer. When heated to around 180 °C (356 °F), the plastic particles absorb the plasticizer, causing them to swell and fuse together forming a viscous gel. Once this is cooled to below 60 °C (140 °F) it becomes a flexible, permanently plasticized solid product. This process is called 'curing'.

Artificial nails, also known as fake nails, false nails, acrylic nails, press ons, nail extensions or nail enhancements, are extensions placed over fingernails as fashion accessories. Many artificial nail designs attempt to mimic the appearance of real fingernails as closely as possible, while others may deliberately stray in favor of an artistic look.

Resin casting is a method of plastic casting where a mold is filled with a liquid synthetic resin, which then hardens. It is primarily used for small-scale production like industrial prototypes and dentistry. It can be done by amateur hobbyists with little initial investment, and is used in the production of collectible toys, models and figures, as well as small-scale jewellery production.

Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be molded, extruded or pressed into solid objects of various shapes. This adaptability, plus a wide range of other properties, such as being lightweight, durable, flexible, and inexpensive to produce, has led to their widespread use. Plastics typically are made through human industrial systems. Most modern plastics are derived from fossil fuel-based chemicals like natural gas or petroleum; however, recent industrial methods use variants made from renewable materials, such as corn or cotton derivatives.

References

1 2 3 Roche, Nan (1992). The New Clay . Gaithersburg, MD 20883 USA: Flower Valley Press. ISBN 0-9620543-4-8.{{cite book}}: CS1 maint: location (link)
↑ Moses, Monica (October–November 2011). "How Polymer Hit the Big Time". American Craft Magazine. Archived from the original on 31 August 2017. Retrieved 3 May 2014.
↑ "STAEDTLER® FIMO® - The history". 2011-05-10.
↑ Stopford W, Turner J, Cappellini D (2003-08-03). "Determination of the Magnitude of Clay to Skin and Skin to Mouth Transfer of Phthalates Associated with the Use of Polymer Clays" (PDF). Division of Occupational & Environmental Medicine. Archived (PDF) from the original on 2012-02-22.
1 2 Sarvetnick HA. (1972). Plastisols and organosols. New York: Van Nostrand Reinhold.
↑ Severs ET, Lebanon M, Frechtling AC (1956-07-03). "Composition comprising a gelling agent and a dispersion of a vinyl resin in a plasticizer". United States Patent Office, patent 2,753,314.
↑ Cahill, Phyllis. "Does Polymer Clay Shrink?". Polymer Clay Journey. Retrieved 13 December 2018.
↑ Cheraghian, Goshtasp (1 January 2017). "Synthesis and properties of polyacrylamide by nanoparticles, effect nanoclay on stability polyacrylamide solution". Micro & Nano Letters. 12 (1): 40–44. doi:10.1049/mnl.2016.0419.
↑ Miller S. (2012). "Health Impacts of Toxins in Polymer Clays". Archived from the original on 2012-12-15. Retrieved 2012-12-19.
↑ Zhang, Mengmei; Buekens, Alfons; Jiang, Xuguang; Li, Xiaodong (July 2015). "Dioxins and polyvinylchloride in combustion and fires". Waste Management & Research. 33 (7): 630–643. doi:10.1177/0734242X15590651. PMID 26185164.
↑ Consumer Product Safety Improvement Act
↑ FDA (2012). "Guidance for Industry Limiting the Use of Certain Phthalates as Excipients in CDER-Regulated Products" (PDF). Food and Drug Administration . Archived (PDF) from the original on 2012-03-01. Retrieved 2012-01-10.

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[Roche-1] 1 2 3 Roche, Nan (1992). The New Clay . Gaithersburg, MD 20883 USA: Flower Valley Press. ISBN 0-9620543-4-8.{{cite book}}: CS1 maint: location (link)

[Moses-2] Moses, Monica (October–November 2011). "How Polymer Hit the Big Time". American Craft Magazine. Archived from the original on 31 August 2017. Retrieved 3 May 2014.

[FIMO-3] "STAEDTLER® FIMO® - The history". 2011-05-10.

[Duketox-4] Stopford W, Turner J, Cappellini D (2003-08-03). "Determination of the Magnitude of Clay to Skin and Skin to Mouth Transfer of Phthalates Associated with the Use of Polymer Clays" (PDF). Division of Occupational & Environmental Medicine. Archived (PDF) from the original on 2012-02-22.

[Plastisols-5] 1 2 Sarvetnick HA. (1972). Plastisols and organosols. New York: Van Nostrand Reinhold.

[Patent-6] Severs ET, Lebanon M, Frechtling AC (1956-07-03). "Composition comprising a gelling agent and a dispersion of a vinyl resin in a plasticizer". United States Patent Office, patent 2,753,314.

[7] Cahill, Phyllis. "Does Polymer Clay Shrink?". Polymer Clay Journey. Retrieved 13 December 2018.

[8] Cheraghian, Goshtasp (1 January 2017). "Synthesis and properties of polyacrylamide by nanoparticles, effect nanoclay on stability polyacrylamide solution". Micro & Nano Letters. 12 (1): 40–44. doi:10.1049/mnl.2016.0419.

[Hazards-9] Miller S. (2012). "Health Impacts of Toxins in Polymer Clays". Archived from the original on 2012-12-15. Retrieved 2012-12-19.

[10] Zhang, Mengmei; Buekens, Alfons; Jiang, Xuguang; Li, Xiaodong (July 2015). "Dioxins and polyvinylchloride in combustion and fires". Waste Management & Research. 33 (7): 630–643. doi:10.1177/0734242X15590651. PMID 26185164.

[11] Consumer Product Safety Improvement Act

[Approved-12] FDA (2012). "Guidance for Industry Limiting the Use of Certain Phthalates as Excipients in CDER-Regulated Products" (PDF). Food and Drug Administration . Archived (PDF) from the original on 2012-03-01. Retrieved 2012-01-10.

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