Harry Bass was the president of the American Numismatic Society during the late 1970's and early '80's. The ANA now houses the Bass Gallery, a learning center for children, named for their deceased president. Earlier in his career, Bass served in the navy and as Dallas county chairman for the Republican Party in the late 1950's. Bass spent over three decades assembling one of the single most highly regarded coin collections in world history. Beginning in 1966 and collecting until his death in 1998, he put together a 6,000-piece collection of the world's finest coins and specialized in gold coin collection. He owned a total of 635 gold dollars. This set is debatably both the most complete, and in the best condition of any in the world. One of the most impressive facts about the set is that contains every known gold coin The United States Mint ever struck, and each is in extraordinary condition. Bass also owned a comprehensive and mint quality collection of $3 gold coins.

Most experts on gold in the US would agree that Bass's collection is one of the most impressive but Doug Winter argues, in an article called "The Bass Collection: Dirty Little Secrets," that the way in which Bass preserved the coins is problematic. Bass did the bulk of his collecting during the 1960's and 1970's. Coins shipped to collectors during this period of time inside of polyvinylchloride (PVC) flaps, popular during the time period for transporting precious objects. This material is based on petroleum and for this reason, it tends to leave a residue which is commonly referred to as "grime" on a coin collection.

Winter says that many of the original coins from Bass's coin collection will read "Harry W. Bass Collection" on their flaps. These are the coins with the most visible amount of grime, or residue, on them. At some point, PCGS attempted to upgrade the wrappers to non-PVC holders. The Bass coins from PCGS placed in the newer holders only say "Bass" on the packaging. NGC, another major coin collection verification service, also certifies a number of coins from the Bass collection. No NGC coins from the collection appear, as far as Winter can see, to bear any evidence of PVC grime on them.

By no means does Winter consider PVC grime to be the end of the world for a collectable coin. Luckily, Bass's collection consist primarily of gold coins which, in comparison to other metals such as copper or silver, do not sustain as much permanent or irreversible damage from bad storing practices. The principle concern Winter expresses is an aesthetic one for this reason. His suggestion is simply that if you happen to possess any coins from the recent Bass collection sales in Baltimore, or those that took place during 1999 and 2,000, you might consider taking them to a specialist to check from PVC grime.