Presentation is loading. Please wait.

Presentation is loading. Please wait.

Introduction to ivory identification Developed by the CITES Secretariat GreenCustoms Knowledge Series No. 12.

Similar presentations


Presentation on theme: "Introduction to ivory identification Developed by the CITES Secretariat GreenCustoms Knowledge Series No. 12."— Presentation transcript:

1 Introduction to ivory identification Developed by the CITES Secretariat GreenCustoms Knowledge Series No. 12

2 2 Questions to answer What is ivory? How long has ivory been used? What kinds of ivory are in trade? How to differentiate between different kinds of ivory? How to identify substitutes? How to spot counterfeit ivory?

3 3 What is ivory? The word “ivory” was traditionally applied only to the tusks of elephants However, the chemical structure of the teeth and tusks of mammals is the same regardless of the species of origin, and the trade in certain teeth and tusks other than elephant is well established and widespread Items from species other than mammals have also been called “ivory”

4 4 What is ivory? Tusks are extremely large teeth projecting beyond the lips Teeth of most mammals consist of a root, a neck and a crown, and a tusk consists of a root and the tusk proper Teeth and tusks have the same physical structures: pulp cavity, dentine, cementum and enamel

5 5 What is ivory? Tooth and tusk ivory can be carved into an almost infinite variety of shapes and objects Tusks can be carved in a way that retains their characteristic shape Warthog tusks, teeth from sperm whales, killer whales and hippos can be superficially carved, and also retain their original shapes

6 6 What is ivory? Ivory can also be found in less-recognizable form, such as inlays and small items

7 7 Ivory in trade Ivory has been valued for a long time, with the first recorded use in carving by Cro-Magnons living from about 40,000 to 10,000 years ago in the Upper Paleolithic period of the Pleistocene epoch

8 8 Ivory in trade Egypt, 2600 BC Europe, 12 th -14 th Centuries

9 9 Ivory in trade Japanese artists starting in the 17th century cleverly invented the miniature sculptures known as netsuke to serve a very practical function (kimonos did not have pockets !) Modern copies of old netsuke designs are popular as art objects, and are often made from ivory

10 10 Ivory in trade Netsuke carvings will have two small holes through which a braided silk cord was passed Genuine items and well-made copies will have holes of different sizes, as the larger hole will accommodate the knot Modern netsuke created as tourist items generally have holes of similar size, or holes that do not connect

11 11 Ivory in trade Modern use and trade –D–Decoration, art –C–Cultural objects –M–Musical instruments –N–Name seals

12 12 Ivory in trade Modern use and trade –D–Decoration, art –C–Cultural objects –M–Musical instruments –N–Name seals

13 13 Ivory in trade Modern use and trade –D–Decoration, art –C–Cultural objects –M–Musical instruments –N–Name seals

14 14 Ivory in trade Modern use and trade –D–Decoration, art –C–Cultural objects –M–Musical instruments –N–Name seals

15 15 Kinds of ivory Elephant (Asian, African) Mammoth (fossil ivory) Hippopotamus Walrus (including fossil walrus ivory) Narwhal Sperm whale Warthog Hornbill Natural substitutes –Bone –Composites –Shell –Vegetable ivory Synthetics, fake ivory –Plastics –Polyester resins –Synthetics –Casein –Celluloid

16 16 Real or fake...? It is not so straightforward, or easy to tell... Ivory identification... and in which CITES Appendix? Bone Celluloid Warthog Synthetic III Walrus II Hippo I Hornbill

17 17 Ivory identification Elephant and Mammoth –Polished cross-sections of elephant and mammoth ivory dentine display uniquely characteristic Schreger lines, commonly referred to as cross-hatchings, engine turnings, or stacked chevrons –The intersections of Schreger lines form angles, which are on average deg. (obtuse) in Asian/African elephant ivory

18 18 Ivory identification Elephant and Mammoth –Polished cross-sections of elephant and mammoth ivory dentine display uniquely characteristic Schreger lines, commonly referred to as cross-hatchings, engine turnings, or stacked chevrons –The intersections of Schreger lines form angles, which are on average deg. (obtuse) in Asian/African elephant ivory Mammoth Elephant

19 19 Mammoth (non-CITES)

20 20 Elephant

21 21 Mammoth (non-CITES)

22 22 Ivory identification Remember, Schreger lines appear in cross-section In a three-dimensional carving, it is usually possible to find a side that corresponds to a cross-section However, items that are cut length-wise in thin layers (such as piano keys) will not have these lines, and may exhibit wavy or parallel lines on their surface

23 23 Ivory identification Mammoth ivory will occasionally display intrusive brownish or blue-green coloured blemishes caused by an iron phosphate called vivianite When the discolouration is barely perceptible to the eye, the use of a hand-held ultraviolet light source causes the blemished area to stand out with a dramatic purple velvet-like appearance Even if discoloured, elephant ivory will not have the characteristic fluorescence of vivianite

24 24 Ivory identification Hippopotamus

25 25 Ivory identification Hippopotamus –Upper and lower canines and incisors are the most common sources for hippo ivory Upper canine is oval to rounded in cross-section Lower canine is large, strongly curved, triangular in cross-section Incisor is peg-shaped, dot in centre of cross-section

26 26 Ivory identification Hippopotamus –Close examination of cross-section of hippo dentine with the aid of a 10X hand lens reveals a tightly packed series of fine concentric lines that can be regularly or irregularly spaced –The orientation of the lines will follow the overall shape of the particular tooth, and the centre of the tooth may display an interstitial zone

27 27 Ivory identification Walrus –Walrus tusk ivory comes from two modified upper canines, which have a rounded, irregular peg shape –The tip of a walrus tusk has an enamel coating which is worn away during the animal’s youth –Fine longitudinal cracks, which appear as radial cracks in cross- section, can be seen throughout the length of the tusk

28 28 Ivory identification Walrus –Walrus tusk ivory comes from two modified upper canines, which have a rounded, irregular peg shape –The tip of a walrus tusk has an enamel coating which is worn away during the animal’s youth –Fine longitudinal cracks, which appear as radial cracks in cross- section, can be seen throughout the length of the tusk

29 29 Ivory identification Walrus –“Fossilized” walrus ivory is also traded (carvings, musical instrument parts)

30 30 Ivory identification Old, new and ‘fossil’ walrus ivory Fossil Old New Old

31 31 Ivory identification Narwhal –Upper incisor, spiral in shape, hollow centre in cross-section

32 32 Ivory identification Sperm whale –Whole teeth –Whole teeth with scrimshaw (surface carving) –Tabua Enamel tip, dentine rings in cross-section Many good fakes, using polyester resin

33 33 Ivory identification Sperm whale –The root cavity of whale teeth is generally deep and conical (except in old animals) –The edge of a whale tooth is fairly sharp, thin, and can exhibit cracks due to age and loss of moisture –If the edge has been trimmed it is usually finished smooth, follows the outside shape of the tooth, and is usually unstained –The base cavity of most fakes is shallow and rounded, and may be discoloured from dye immersion to simulate patina on the outer surface

34 34 Ivory identification Sperm whale –The tip of a sperm whale tooth is yellowish, with a sharp line separating tip from the whiter ivory, and may also display sharp, thin and short age lines, crossing from ivory to crown –The patina is usually subtle and not uniform, and will not easily scratch off; it is also a different color than ink of the scribed image –Very few authentic antique scrimshaw have text, and even fewer are dated –With many of the resins now in use, “hot-needle” tests and UV-light examination are not as reliable as they once were

35 35 Ivory identification Warthog –Warthog ivory comes from the animal’s upper and lower canine teeth –These tusks are strongly curved and have generally squared cross-sections –Warthog ivory tends to have a mottled appearance –Examination of a cross-section with a 10X hand lens reveals that warthog dentine shows irregularly spaced concentric lines of varying thickness

36 36 Ivory identification Hornbill –Hornbill ‘ivory’ is derived from the casque of the Helmeted hornbill Rhinoplax vigil

37 37 Ivory identification Natural substitutes –Bone c an superficially look very much like ivory Bone is e xtensively permeated by Haversian pits or canals through which fluid flows These can be seen on a polished bone surface using a 10X hand lens, appearing as pits or scratch-like irregularities

38 38 Ivory identification Natural substitutes –Composites Elephant ivory dust, a by-product of carving and manufacturing, can be bound with resins and molded or cut and polished to make a commercially usable product (e.g. for piano keys) Technically it is still an ivory specimen, but it will not have the usual identification characteristics

39 39 Natural substitutes –Shell Polished calcium carbonate, for inlays and small items –Vegetable ivory (tagua palm nut) Cross-section reveals fine, regularly spaced concentric lines similar to those seen in hippopotamus ivory Vegetable ivory UV fluorescence is very similar to elephant ivory fluorescence –Sulphuric acid applied to vegetable ivory causes an irreversible pink coloring in about 12 minutes Ivory identification

40 40 Asian- style and modern tagua nut carvings

41 41 Ivory identification Synthetics, fakes –Plastics, polyester resins, synthetics, casein, celluloid –Some try to mimic the Schreger lines (such as celluloid, invented in 1869 – which means you can have old fakes)

42 42 Summary Ivory has been in use for a very long time –There is a lot of it out there...! There are different kinds of ivory, each with various morphological characteristics Preliminary identification can sometimes be done in the hand, aided by a hand lens......but you might not be able to do it without more sophisticated equipment and a laboratory, and perhaps reference material for comparison

43 43 CITES Secretariat Geneva


Download ppt "Introduction to ivory identification Developed by the CITES Secretariat GreenCustoms Knowledge Series No. 12."

Similar presentations


Ads by Google