Why do I have a bluish ‘rainbow’ marking on my stainless steel?

This is a clear sign that the pan has been over heated. Stainless steel reacts to high heat, by turning a bluey-purple colour (Similar to the colours of a rainbow). It is important that you always match the size of the pan to the size of the ring you are cooking. Heat the food more gently and when possible turn the heat down. This will save energy and also retain more flavours and goodness. This is especially important where the pan has a thick base. Once the pan base has heated up it retains the heat longer compared to a thinner saucepan so food will continue cooking, even after the heat source has been switched off.

Marks like this can be removed with the Steelfix Stainless Steel Cleaner, that can be purchased here.