Chloe Zhang
Ivory is a valuable material that has traditionally been used to make figures, buttons, combs, chess boards, and more. It is sourced from the tusks or teeth of animals such as elephants, hippopotamuses, narwhal whales, and wild boars. With the increasing restrictions on the use of ivory, distinguishing it from plastic has become a challenging task. Some of the ways to identify genuine ivory include examining its weight, texture, and reaction to light and heat. Plastic ivory substitutes often exhibit jagged-edged pits and broken bubbles on their surfaces, and they tend to be lighter and less dense than genuine ivory. Under black light, plastic ivory fluoresces blue or blue-white, and when a hot needle is pressed against it, it gives off a chemical smell. On the other hand, genuine ivory is heavy and cold to the touch, and it may have Schreger lines, which are rows of microscopic tubes that appear as cross-hatching or circular rings.
| Characteristics | Values |
|---|---|
| Weight | Ivory is heavy and dense, whereas plastic is usually lighter. |
| Texture | Ivory has a smooth texture with Schreger lines, which are rows of microscopic tubes. Plastic has jagged-edged pits and broken bubbles on its surface. |
| Colour | Ivory is off-white, whereas plastic may be translucent. |
| Fluorescence | Plastic and resin artificial ivories fluoresce blue or blue-white under black light. |
| Feel | Ivory is cold to the touch. |
| Seam | Plastic often has a seam that can be detected. |
| Sound | Plastic makes a distinct sound when tapped. |
| Reaction to hot needle | Ivory does not press in when a hot needle is pressed against it and may smell slightly of bone. Plastic will press in easily and smell like chemicals. |
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What You'll Learn
Use a magnifying glass to check for Schreger lines
To distinguish ivory from plastic, one of the tests you can perform is to use a magnifying glass to check for Schreger lines.
Schreger lines are a unique pattern of cross-hatching that appears in cross-sections of elephant tusks. They are rows of microscopic tubes that form what are known as Schreger angles where they intersect. These lines have never been replicated in artificial plastics or resins, so their presence always indicates elephant ivory.
The Schreger lines can be seen most easily at the bases of figures and anywhere cuts are made at right angles to the grain. However, they may not always be obvious, and depending on how the ivory was cut, they may not always be visible. Therefore, it is a myth that ivory will always have these lines, and their absence does not necessarily indicate that the substance is not ivory.
To check for Schreger lines, you can use a standard-strength, handheld magnifying glass, which can be purchased online or at specialty and hobby retailers. Hold the magnifying glass a few inches away from the surface of the object you are examining. If the object is made of ivory, you should see lines on its surface. These lines can appear in various forms, including straight, cross-hatched, or circular.
It is important to note that the presence of Schreger lines is not the only factor in determining whether an object is made of ivory. Other tests, such as fluorescence under black light and the hot needle test, can also be used in conjunction with the magnifying glass test to help identify ivory more conclusively.
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Weigh the item—plastic is usually lighter than ivory
One of the easiest ways to distinguish ivory from plastic is by weighing the item. Plastic is usually lighter than ivory. Hold the item in your hand and assess its weight. If it feels lightweight, it is most likely not ivory, although it could be bone. Ivory is heavy and dense, similar in weight to a billiard ball. However, bone and ivory can weigh the same, so this is not a definitive test. If you are unsure, use a scale to weigh the item.
To further aid your assessment, examine the item under a magnifying glass. Ivory will have lines on its surface, which can appear straight, cross-hatched, or in a circular motion. These are known as Schreger Lines and are rows of microscopic tubes. Plastic, on the other hand, will not have these lines and will appear non-descript upon magnification.
Another test you can perform is the hot needle test. Press the tip of a hot needle to the surface of the item. If it is ivory, it will not press in and may slightly smell of bone. If it is plastic, the needle will press in easily and emit a chemical odour. However, this test can damage or ruin your piece, so it is not recommended by experts.
Finally, observe the item closely for any seams or joints. Ivory carvings are typically made from a single piece of solid ivory, whereas plastic items often have seams that are detectable under inspection.
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Check for jagged pits and bubbles—typical in plastic
One of the key ways to distinguish ivory from plastic is to look for jagged pits and bubbles, which are typical of plastic. Plastic and resin substitutes for ivory are usually moulded, and the trapped air and expanding gas from impurities almost always cause rounded smooth-backed holes in the finished surface. These jagged pits and bubbles are not found in genuine ivory.
Plastic ivory imitations are often made from resin or some form of plastic, and these materials are almost always moulded. The process of moulding plastic often results in these jagged pits and bubbles, which are a tell-tale sign of a fake. Genuine ivory, on the other hand, does not have these imperfections and usually has a smooth, uniform surface when viewed from a distance.
When examining a piece for these imperfections, it is advisable to use a magnifying glass or microscope to get a detailed view of the surface. This will allow you to see any irregularities in the surface structure that could indicate the presence of plastic. The naked eye may not always be able to detect these subtle differences, so magnification can be a useful tool.
It is important to note that not all plastics will have these pits and bubbles, and some higher-quality imitations may have a more uniform surface. However, the presence of these imperfections is a strong indicator of plastic, and their absence does not necessarily confirm genuine ivory. Other tests, such as examining the weight, colour, and texture of the piece, should also be conducted to comprehensively identify the material.
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Use black light—plastic fluoresces blue or blue/white
Black lights emit ultraviolet (UV) light that is invisible to humans. When exposed to UV light, certain fluorescent substances absorb the light and re-emit it at a different wavelength, making the light visible and causing the material to appear to glow. This phenomenon is called fluorescence.
Virtually all plastic and resin artificial ivories fluoresce blue or blue/white under black light. Therefore, a black light can be used to distinguish ivory from plastic. If the object in question fluoresces blue or blue/white under a black light, it is likely plastic.
Other substances that fluoresce under black light include tonic water, which glows blue-white; quinine, which also glows blue-white; vitamin A and B vitamins thiamine, niacin, and riboflavin; scorpion species, such as the emperor scorpion, which normally appears dark brown or black but glows bright blue-green under black light; and many plastics, such as neon-coloured acrylic, plastic water bottles, and white paper.
Some other objects that glow under black light are fingernails, laundry detergent, highlighters, money, and teeth.
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Feel for a seam, often detectable in moulded plastic
One of the ways to distinguish ivory from plastic is by feeling for a seam. According to Jeanenne Bell, owner of Jewelry Box Antiques in Kansas City, Missouri, you can often rely on your senses to test your ivory. She recommends using your hands, eyes, and even your teeth. One of the ways to do this is by feeling for a seam that is often detectable in moulded plastic.
When examining a piece of ivory, it is important to look for any seams or joints that could indicate it is made of plastic. Virtually all old ivory carvings are made of single pieces of solid ivory, whereas plastic imitations often have seams where two pieces of plastic have been joined together. These seams can be felt by running your fingers over the surface of the object. If you detect a seam, it is likely that the object is made of plastic rather than ivory.
However, it is important to note that the absence of a seam does not necessarily mean that the object is made of ivory. Some plastic imitations may not have seams, or the seams may be well-hidden. Therefore, it is important to use other tests in conjunction with feeling for a seam to determine whether an object is made of ivory or plastic.
One such test is the weight test. Ivory is typically heavier than plastic, so picking up an object and feeling its weight can be a good indicator of whether it is made of ivory or plastic. Another test is the hot needle test, which involves pressing the tip of a hot needle to the surface of the object. If the needle presses in easily and smells like chemicals, it is likely plastic. If it does not press in and smells like bone, it may be ivory. However, this test can char and damage the object, so it is not recommended by experts.
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Frequently asked questions
Ivory is heavy and cold to the touch when you put it to your cheek. It will usually have Schreger lines, which can be straight, cross-hatched, or in a circular motion. Plastic is usually lighter than ivory and will not have these lines.
Schreger lines are rows of microscopic tubes that appear in cross sections of elephant tusks. They are unique to elephant ivory and have never been duplicated in artificial plastics or resins.
Yes, you can use a magnifying glass or microscope to examine the item more closely. Plastic is non-descript upon magnification, whereas ivory will have visible cross-hatches on its surface.
