The tingling spoon

[Simpo Two]

I have a set of Swedish Gense stainless steel spoons c. late 1950s. They are marked '18-8'.

Last night I discovered that from the edge of one, if I put my tongue on it, I get a slight tingle. I associate this with mixed metals setting up a potential difference using my saliva as an electrolyte - for example when plating wears off. However the spoons are, I believe, solid stainless steel. What could be causing one spoon to give this affect? The others are fine.

[Simpo Two]

Dessert spoons...!

[Simpo Two]

IainT said:

Do you have any fillings?

Yes, and some are amalgam. But then all the spoons would do it... perhaps there is a speck of impurity in that particular spoon which has been exposed by wear over the years? Nothing visible though.

[Simpo Two]

IainT said:

Only the edge of one specific spoon, not the edge of all? The edge could be pertinent as it's focus the current at a point on the tongue that you wouldn't be sensitive enough to notice on the flat but if it's only one spoon then I'd think you're right - an impurity in the metal.

Yep, just one spoon.

Evidently strawberry cheesecake is a good catalyst!