George Foreman Grill Plates

[unigirl]

Does anyone know why when I place my George Foreman grill plates in the dishwasher, they are covered with a fine, black powder on the underside. It looks like soot and blackens my fingers when I remove the plates. What type of metal are these plates made from and why does this happen.

It's all so annoying and yes, George Foreman does state that the plates can be run through the dishwasher.

Thank you.

[unigirl]

Sorry, should have made clear that the sooty deposit is seen after the dishwasher has run the cleaning cycle. Temperature appears immaterial.

[jomifl]

If the plates are made of cast iron then the sooty powder could be carbon particles released from the cast iron by the chemicals in the dishwasher powder. Cast iron contains quite a large volume of carbon in the spaces between the iron crystals. This can be seen where cast iron has been corroded under anoxic conditions so that instead of rusting the iron dissolves leaving a carbon replica behind.

[unigirl]

Thanks jomifl. I now understand why the powdery deposit looks like soot as I've always understood soot to be almost pure carbon.

Thanks again.

[EDDIE51]

Most contact grill Gorge Forman) plates are Aluminium alloy with a small % of Copper.
If you are using dish washer tablets with a high alkali content and a lot of them are , the alkaline wash water will attack the Aluminium and leave the Copper as a black residue on the surface of the plates. No matter what the manufacture says I would not put the plates through a dishwasher , just remove them and wash in the sink with standard washing up liquid . If they are cleaned after each use they should not need a dishwasher . The same applies to Lead crystal glass it is attacked by the alkali and should never be put in a dishwasher.

[unigirl]

Thanks EDDIE51. On thinking about it, the underside of the plates look more like aluminium than cast iron.

[EDDIE51]

All the GF grill plates I have seen are Aluminium alloy as it transmits the heat better than cast Iron and is a lot lighter . As I said no Aluminium item should be put into a dish washer as the Alkaline wash tablets will etch it , so never put an Aluminium pan into a dish washer either.

[jomifl]

I agree with Eddie 100%. If the black powder is carbon it will burn away if exposed to a flame, if it is copper oxide it will give a blue/ green colour to the flame and will dissolve in hydrochloric acid to give a blue coloured solution. It would be easier to see if the plate is magnetic, if not then don't bother to get your chemistr set out.