Are PCGS holders airtight? No, and we know it thanks to a cricket

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One of the big questions that many people ask about coin grading by companies such as PCGS is whether their famous holders, also known as slabs, are airtight or, conversely, the let air in.

Today, we know that no, the pre-2015 holders are not airtight and yes, they let air in. And one of the ways we know this is tremendously strange: at PCGS, they caught a cricket and put it in a slab.

The Legend of the Cricket

Legend has it that in 1999 or 2000, a cricket sneaked into the PCGS grading offices. And it became so annoying that they had no choice but to catch it. After a few attempts, one of the employees managed to trap it inside a holder.

Here it is (photos from September 2021):

PCGS Holder Cricket - Obverse
The front (Photo: Great Collections).
PCGS Holder Cricket - Reverse
The back (Photo: Great Collections).

Now the problem shifted: what could they do with a holder with a cricket inside?

After a meeting with the bosses, it was decided to give it as a present to one of the foremost experts in numismatic errors in the United States, Fred Weinberg.

You can listen to Weinberg himself telling the story here:

Since then, Weinberg has carefully kept it, and he has rarely shown it in public: in 20 years, he has only taken it to a couple of American numismatic conventions, and it has received a mention in David Schwager’s Sample Slabs holder label catalog.

PCGS Holder Cricket - Book Description
Page 394 of “Sample Slabs”, featuring the holder with the cricket.

In 2021, the slab with the cricket was finally auctioned off at Great Collections. The hammer price was $5,350.

Preservation of the corpse and the non-airtight slab

If you compare the photos from the book page with the auction photos, the first thing that stands out is that the position of the cricket’s corpse is not the same. I believe this to be normal: a slab is made to hold coins, not crickets.

But if you look closely, it seems that the color of the cricket in the auction images is also darker than in the book. This indicates one thing: there has been a process of oxidation inside the slab. And oxidation occurs when a material is in direct contact with oxygen.

If you remember your high school chemistry lessons, or if you look at any banana peel you’ve thrown away, you’ll remember that organic material oxidizes much more quickly than inorganic material.

Eurozone - 1 Euro Cent - Regular vs Oxidized
Regular 1 euro cent coin, and one that has undergone extreme oxidation (Photo: Pixabay/stux).

The cricket is organic material, while the metal with which any coin is made is inorganic. Therefore, the cricket gives us an accelerated view of the oxidation process that occurs inside the capsule, in the numismatic version of speeding up a Youtube video.

The conclusion of all this is that, indeed, the ultrasonic welding that seals both sides of a PCGS holder is not airtight and does allow air to pass through.

Ultrasonic Welding Process
Diagram of the ultrasonic welding process (Photo: Commons/Four30).

In fact, Weinberg himself, in the video you can watch above, says that if someone were to attempt to break the ultrasonic weld to re-slab the cricket, it’s highly likely that the corpse would disintegrate due to oxidation and the force required to open the holder.

Reactions from NGC and PCGS

The NGC and PGCS holders are technologically similar but different in design, so these conclusions cannot be applied to the former.

But it’s not a problem, NGC itself already openly states in its FAQ that its capsules are not completely airtight either.

As for PCGS, in 2015 they introduced a new holder design. And they claim that, unlike the previous model, which is the one containing the cricket, this time they are “virtually airtight.” It remains to be seen what exactly “virtually” means.

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