十万个为什么·科学启蒙30篇（3）

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为什么银器会变黑

My grandma’s silver spoons look dull and gray after sitting in the drawer for weeks.
This dark film forms when silver meets tiny bits of sulfur in the air or food.
Eggs, onions, and rubber bands make silver darken faster than other items.
I help polish them gently with a soft cloth and special silver cleaner.
We store them in cloth bags to keep air and moisture away from the surface.
The black layer isn’t rust—it’s called tarnish and doesn’t harm the metal.
Sometimes I notice it first on the fork tines where food touches most often.
My dad says polishing feels like giving old things a fresh, shiny welcome back.
Even new silver will darken if left out near a kitchen stove or window.
After cleaning, the spoons sparkle again when we set the table for dinner.