Attempts have been made in the past to construct jewellery utilizing mammoth ivory in combination with inlaid gemstones. A variety of such jewellery pieces are known such as mammoth ivory Hanko and mosaic mammoth ivory cabochons and mosaic mammoth ivory jewellery and object d'art.
The manufacture of such jewellery pieces has been difficult due to problems such as cracking of the mammoth ivory, cracking of the inlaid gemstones and separation of joints between the constituent materials (mammoth ivory, gemstones, adhesive material, etc). For example, exposure of the mammoth ivory to elements of water, permafrost and ground minerals results in cracks in the ivory, added moisture, weakened internal strength and contamination of the ivory composition. Furthermore, the combination of different constituent materials having different expansion rates contributes to the separation of the joints therebetween. Finally, the artistic design of the jewellery often presents problems in the bonding characteristics of the adhesive.
It has been determined that the main reason for movement in mammoth ivory is that the material is capable of absorbing enough moisture to reach its saturation point which causes expansion. Thus, as with wood, the raw material has to be cured to an acceptable relative humidity before further processing can be pursued. If the relative humidity is different than the ambient humidity, then there will be a transfer from the higher humidity level to the lower humidity level. This results in expansion or contraction of the piece, causing it to crack.
Attempts have been made in the prior art to overcome the problems discussed above.
Acrylic coatings have been applied to assembled pieces in order to act as a "cocoon" for sealing and binding the composite piece. However, the acrylic coatings have been found to be merely a temporary solution for two reasons. Firstly, since the raw material contains a certain amount of moisture, the moisture escapes through osmosis and tends to crack or separate the jewellery piece. Secondly, even if the moisture has been removed, available coatings are too soft to withstand long term usage. The results using this prior art solution include surface scratching and a discolouration of the coatings.
Oils have been applied in mammoth ivory jewellery pieces to replace natural oils lost due to the exposure of the ivory to natural elements. However, such oils have proven to be an unpleasureable experience for the craftsman to apply and for the consumer to wear.
Different adhesive materials have been utilized in an attempt to eliminate separation. Such adhesive materials come in many different varieties from polymers, epoxies, fibreglass and cyano-acrylids to name a few. Most available adhesives are designed to either penetrate materials or to act as binders, but not both. To date, no suitable adhesive material has been found which provides adequate penetration and binding characteristics for use in the construction of mammoth ivory jewellery.
Internal pins have also been inserted into mammoth ivory jewellery pieces in an attempt to eliminate separation. While the internal pins do solve the problem of keeping the piece together, the pins do not allow the jewellery piece to expand and contract in its desired surface direction. Therefore, the piece tends to buckle away from the direction of the pins. Furthermore, the use of pins in the production of jewellery has been found to be unduly expensive.
A variety of curing techniques have also been used in an attempt to reduce internal stress and moisture in mammoth ivory. Many forms of curing have been applied, from microwave ovens, hot lights in a heat box, to dry warehouse storage. All of these methods have been found to either destroy the material or to require excessive curing times.
USPTO Backgrounds
USPTO Backgrounds