PVC Contamination on Modern Chinese Coins and the NCS Solution
Posted on 11/9/2012
Modern Chinese coinage began in 1979 with the introduction of the silver and gold commemorative coins and medals programs. This first year included four series: two coin sets and two medal sets. The coin sets were: the People’s Republic of China Anniversary set of four gold coins and the Year of the Child silver and gold coin set. The medal sets were the Fourth National Sports Meeting consisting of one issue in gold and three in silver and the Beijing Scenery Commemorative series in gold consisting of five designs. In 1982, China began its widely popular Panda precious metal bullion program. Gold Pandas (ranging in the size from 1/10 ounce to one ounce) were introduced that year, followed by the silver one ounce coin the next year.
There are several types of official packaging for these coins and medals. Many Gold Panda coins were simply sealed in soft plastic.
Others were placed in capsules first, and then sealed in this soft plastic.
Other coins and sets were put in capsules and then placed in display boxes (many of which are elaborately painted wooden boxes).
Although plastic is convenient and inexpensive, this plastic can cause serious problems with coins. The softness and pliability of the plastic is due to the use of PVC, or Polyvinyl Chloride. Unfortunately, this reacts negatively with the coin under most conditions, especially areas with high humidity or heat. As a result, many Chinese modern coins exhibit PVC residue and/or damage. Coins with active PVC residue are not eligible for NGC certification.
Thankfully, the professional conservators at Numismatic Conservation Services (NCS) can safely remove PVC residue and, in many cases, the coins can then be numerically graded by NGC. In this article, we will highlight two gold coins that best exemplify what happens to coins stored in PVC plastic, and the difference conservation by NCS can make.
The first coin is a China 1986 Panda 12 Ounce Gold 1,000 Yuan. The first four photos illustrate the poor condition of the coin when it arrived at NCS. It was still in the original plastic and was completely covered with PVC residue and numerous copper spots (red dots that are often seen on gold coins). The residue made the coin unsuitable for NGC certification.
During conservation, the PVC residue and copper spots were removed, and the coin’s surfaces neutralized to ensure long-term protection. This coin was now fit for NGC certification.
The second coin is a China 1993 Guanyin 1/10 Ounce Gold 10 Yuan, also with PVC residue and copper spots.
The residue prevents the coin from being certified, while these unsightly spots can also severely affect the eye appeal and grade of the coin. In this case, the red copper spots are far more prominent than the cloudiness caused by the residue. Following professional conservation, the coin again displays its original luster and full detail. It is now a highly collectible coin.