The concept of the conservation of amber using a vacuum embedding process is based on the polymerization of certain synthetic resins bonding with the surface of the amber. These synthetic resins are mixed in two parts and use a polymerization/catalyzing agent for hardening. When amber is embedded in these synthetic resins under vacuum, the reduced pressure allows the embedding medium to fill fractures in the amber’s surface (mostly microscopic). This greatly improves the optical clarity of the amber under the microscope, and completely stabilizes the amber for scientific study and long term preservation in private/museum collections.The idea of vacuum embedding amber for study is not a new concept. This process was first developed and used to work with the extremely fragile Lebanese amber in the 1970’s. This process was further refined, and has been used extensively in recent years by the American Museum of Natural History; and others for scientific study of amber inclusions. Research on various embedding mediums is ongoing. Most of the embedding mediums being researched at the present time are epox-ides. However, since this research is ongoing; there may be other synthetic resins that may be useful for vacuum embedding amber. 
One synthetic resin of interest is clear polyester resin, due to its superior clarity to epoxy and low cost. Polyester resin has been successfully used for embedding amber, but has only been used experimentally. It is currently known that polyester resin chemically does not polymerize as much as epoxides, and theoretically does not adhere to the amber as well. More research may be needed to fully understand which synthetic resins are best used for the conservation of amber. It is useful to note that vacuum embedding is regularly used by museums for preparing amber with scientifically valuable inclusions; however it may also be a valuable tool for searching very fragile rough amber for inclusions. To begin this process, it is useful to adhere the sample to the bottom of the mold with a fast setting epoxy. (Because this does not harden to be of the same clarity as the embedding medium, the adhesive is needed to be sanded away from the finished embedding. Therefore, only a small amount is recommended to be used.) Adhering the amber to the bottom of the mold allows you to orient the piece of amber in a way that is best suited for the preparation of the sample. The two part synthetic resin is mixed thoroughly, but in a way in which air is not heavily introduced into the resin. (Allowing the mixed resin sit undisturbed for a few minutes before pouring may allow some of the air to evaporate out of the resin. This may vary upon embedding mediums). This is then poured into the mold containing the piece of amber, and air bubbles are moved away with a pin. The embedding is then placed into the vacuum bell jar at 3-4psi of pressure. After 5-10 minutes under vacuum (depending on embedding medium; hardening time of different resins vary), the embedding is then removed. Air bubbles are then moved away with a pin (avoid scratching the ambers surface), and the embedding is allowed to harden under normal conditions. This finished embedding is then cut, sanded, and polished to a very fine surface. This is the standard method for vacuum embedding amber. (Please note that one side of the amber will be exposed to the surface of the embedding, this is a “single embedding”). This “single embedding” can then be embedded a second time. A “double embedding” completely surrounds the amber, with no surfaces of the sample exposed to the surface. The amber is completely sealed from atmospheric oxygen in a double embedding. Therefore, the piece of amber is perfectly centered inside a block of resin, with all surfaces of the sample preserved inside the embedding. Vacuum embedding is a beneficial tool for preserving class I ambers, but has only been used with limited success with class II ambers. Vacuum embedding class II Amber with epoxides is long been known for the embedding pulling away from the sample in a very short period of time. This short period of time does not allow for the thorough research of the sample. Recently Borneo amber from the Merit-Pila Coal mine in Sarawak, Malaysia (class II amber; 15-17 MA) has been successfully double embedded using polyester resin as the embedding medium. The life of this preparation is not known, ageing tests are needed to confirm the life of this embedding. Synthetic resins for the most part suffer the same deterioration as amber over time. Since they are both resins, over time they will darken, craze, develop surface oxidation, etc. The basic principle behind vacuum embedding for the long term conservation of amber is that the embedding will oxidize and decay faster than the amber itself. Vacuum embedding physically improves amber in many ways. Samples are preserved from further deterioration over time, and are far easier to handle during study. The world’s treasure of amber inclusions and window to ancient life must be preserved for future scientists to study.
Kevin Chomicki
