Antiseize on spark plugs

[cousincletus]

I haver always used the copper based antisieze with good results but was wondering what happens if you are sloppy with the antisieze (like me) and get some on the threads that enter the combustion chamber?

 

[TheTanSedan]

At the very least, causes hot spots leading to preignition (bad, very bad). Also, likely, contributes to ring fouling. Picture in my head is that it would harden and take an air hammer to remove. Could be wrong, but . . . .