Hard boiled eggs

[lecheekyworm]

How is it that when I hard boil eggs there is a horrible white rim in the saucepan which is very difficult to remove.  On the other hand when I boil potatoes there is no watermark.  The water is from the same tap and I guess I live in a hard water area - but why the eggs and not the pots or veg. I do not add salt to any of them.

[kempie]

An eggshell is made up of 94% Calcium Carbonate some of which dissolves into the water during the boiling process. Dissolved mineral carbonates are the substances which make water 'hard'.

[flaming]

I can get the white ring off the saucepan by washing it very soon after the eggs are done.  A non-stick saucepan, rub hard perhaps with a bit of wash-up liquid. rinse and wipe straightaway. I( use free-range eggs).  Anything which really adheres to a pan, or is a bit burn, comes off after simmring it containing a solution of water and wash-up liquid. The pan is much easier to clean.

[netibiza]

Thank you both xx