NGC Collection Management & Storage 2

Question 1

Which environmental condition poses the greatest long-term risk to silver coins stored in a home collection?

Accepted Answer

Hydrogen sulfide gas from rubber or wool

Answer

Hydrogen sulfide gas, emitted by rubber bands, wool, and certain plastics, reacts with silver to form silver sulfide toning and tarnish.

Question 2

What does the term 'PVC damage' refer to in numismatic coin storage?

Accepted Answer

Green slime residue from plasticizers in soft vinyl holders

Answer

PVC (polyvinyl chloride) flips contain plasticizers that leach out over time, leaving a green, oily residue on coin surfaces that can etch the metal.

Question 3

When building a type set of U.S. coinage, what organizational principle is typically followed?

Accepted Answer

Collecting one coin of each design type regardless of denomination

Answer

A type set consists of one representative coin for each major design type, emphasizing design variety over complete date-and-mint runs.

Question 4

Which of the following is the safest long-term storage medium for paper currency and banknotes?

Accepted Answer

Archival polyester (Mylar) currency sleeves

Answer

Archival-grade polyester (Mylar/Melinex) sleeves are chemically inert, acid-free, and non-reactive, making them ideal for long-term banknote preservation.

Question 5

A collector discovers that an old 2x2 cardboard flip has left a ring impression on a coin's surface. What caused this?

Accepted Answer

Acid migration from the cardboard staple area

Answer

Acids in non-archival cardboard can migrate to the coin's surface, leaving a ghost ring or stain corresponding to the flip's window or edge.

(NGC) Numismatic Guaranty Corporation Certified Professional Practice Test

(NGC) Numismatic Guaranty Corporation Certified Professional Practice Test

NGC Collection Management & Storage 2