Stan McDonald - author 's Blog

13 Oct 2021

Occluded Gas

Coins | Stan McDonald - author

Occluded gas occurs when there is reside on the surface of a coin from the wash tank. The gas resides escapes when the coin is plated, creating bubbles on the surface of the coin. More familiar to the late 1980s, when the mint was experiencing cleaning issues from the wash tank. Although not as common, there are coins dated in the 1990s and after with occluded gas issues.
In the first photo is a 1982-D Lincoln cent with extensive gas bubbles encapsulated by NGC. The second photo shows a rare 2021 Lincoln cent with occuled gas.
Stan McDonald - Author of error coin guides



Level 5

Do these have any numismatic value?

Under $10, even in a certified holder.


Level 6

Really interesting! Thanks! ; )

I think I had one with a dot... I don't know for sure.


Level 5

You're right about this problem on proof coins. I have a 1984-S proof Lincoln Cent with this problem, and I have always wondered what caused it. Now I know. Thanks for your post and explanation. Follow this link for a picture https://www.ngccoin.com/registry/competitive-sets/73886/coins/600020/

It's Mokie

Level 6

I think Steel Cents also suffered from that malady.

Steel coins rusted after a few years. Most of the BU samples you will find have been resurfaced.


Level 5

Man, that seems like a good starter error for all you beginner roll searchers out there. Great blog, thanks for the info.

AC coin$

Level 6

Interesting nice coin never see proof example. thanks good blesse


Level 6

Good explanation of the problem


Level 5

Interesting issue for coins. Minting coins has many potential problems. Thanks


Level 4

Yes those early plated cents did not hold up well and half the time like your specimens they never had a chance. I have even seen proof examples with gas bubbles.


Level 5

I see those every day.


Level 6

Nicely done. I have seen less nasty examples. Thanks.

Looks like Abe walked into a swarm of flies.


Level 7

These I have seen. Going back to 1797 half penny's made in Britain. And here.

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