My stainless steel burner caps / pan stands / burner supports / hob top is discoloured, is there a problem?

Q) My stainless steel burner caps / pan stands / burner supports / hob top is discoloured, is there a problem?


A) No. This is an expected reaction to the stainless steel being subjected to heat and atmosphere. There is not a fault with the stainless steel.


Laboratory tests done to establish the published heat tint colour charts have usually been based on heating for one hour. As exposure time is increased, the temper colours can be expected to deepen ie make it appear that a higher exposure temperature may have been used.


The original surface finish on the steel can affect the rate of oxidation and the appearance of the colour formed. Rougher surfaces may oxidize at a higher rate and so could appear as deeper colours for any given set of conditions. As the colours formed are by light interference, then the smoothness of the surface can also affect the appearance of the colours formed. There is no specific data published that compares the effect of surface finish, but it is worth noting that surface finish can influence the conclusion on heating temperature, from the colours seen.


The table below represents the temper colours that are likely to form on stainless steel type 1.4301 (AISI 304) if heated in air.


THIS INFORMATION MUST BE USED WITH CARE WHEN INTREPETING THE HINT TINT COLOURS OBSERVED ON STAINLESS STEEL SURFACES AS THE HEATING CONDITIONS ARE NOT SPECIFIED.


Colour Formed

Approx Temperature C


pale yellow

290


straw yellow

340


dark yellow

370


brown

390


purple brown

420


dark purple

450


blue

540


dark blue

600