Gas Cooker Hob

[neuron]

We've got a Cannon Salisbury free standing gas cooker. The hob has four burners and each burner consists of a dark grey burner head capped by a black enamelled burner cap.

The burner head is removable and is the part that has slots cut in it to allow the gas from the centre jet to come out.

I put the burner heads and caps in the dishwasher to clean them every so often. When they come out, they have a film of black powdery stuff all over them which comes off on my hands and is difficult to clean off my hands with soap and water. It looks like I've passed my fingers along a piece of wet coal

Even if I wash the burners by hand, more or less the same thing happens.

I can only assume that the burner is made of some sort of special alloy. Does anyone know what it is called?

I've also noticed this black coating on the outer walls of some of the pans used in deep fat friers. It's generally OK until it's washed.

Many thanks.