I bought this George Forman Grill with detachable trays that are supposed to be dishwasher safe. I noticed that after the dishwasher there's this black soot on them. What causes this? Is there anyway of preventing it? The drip tray that came with the grill has written on it "wash in top rack only", should the same be done with actual grills? What difference does it make if something is washed in the top or bottom rack?

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  • 4
    Re: Using the top rack - most dishwashers have the heating element near the bottom rack. Items that are claimed to be safe in the top rack only might melt or warp if you wash them in the bottom rack.
    – Aaronut
    Mar 15, 2015 at 3:07
  • I sometimes get soap residue sticking to pots and pans when washing them in the dishwasher. Nothing like that though. What's the tray made out of?
    – Ross Ridge
    Mar 15, 2015 at 3:31
  • @RossRidge metal (aluminum I think), it's supposed to be stick free but that's the other side.
    – Celeritas
    Mar 15, 2015 at 8:21
  • 1
    I have the exact same problem with my George Forman grill. It's awful. I have tried handwashing just to get the black stuff off but there seems to be no end to it. They are in the dishwasher right now but I guess going forward I'll just hand wash and see if it ever stops producing this black soot.
    – Jim H
    Feb 4, 2018 at 18:13

5 Answers 5


Most likely your problem is caused by your dishwasher detergent. Many of them will cause aluminum to oxidize creating the issue you are experiencing.

I would suggest that you hand-wash and remove the oxidation as it looks quite extreme. (You don't want any of it to come off in the dishwasher and be deposited on other dishes.)

While it technically may be 'dishwasher safe', to prevent the oxidation from reoccurring I would recommend going forward that you hand-wash. The other option may be to try different dishwasher detergents to see if you can find one that does not cause this reaction.

  • 1
    I hope that's not the cooking surface....Uuuughhh!!!!
    – Escoce
    Mar 17, 2015 at 15:27

It's definitely oxidation. I bought a new dishwasher recently and that same thing is now happening to all the outside bottoms of my nonstick pots & pans. At the same time I switched from powder dishwasher detergent to those muti-colored liquid pouches, so I'm not sure if it's the new dishwasher which gets hotter than the old one or if it's the new detergent or a combination of both. Super annoying. The reason most people own a dishwasher is so they don't have to wash things by hand... duh.


I also have the exact same model and the same issue. I'm sure that it's an oxidation layer that is likely caused by the dishwasher detergents. It's however not preventable as its an unwanted side effect of this particular kind of aluminum alloy. I had some pots that exhibited the exact same problem. I got rid of them all because they drove me crazy. I paid some extra bucks for a quality set of pots that have a better aluminum alloy that won't corrode.

Unfortunately, the ceramic coating got damaged at the small dotted line in the middle lower plate due to repeated mechanical contact with the top. It is a design flaw that happened twice for me in the last 2 years. As this oxidized aluminum is not healthy, I have to throw it away. I'm done with this grill and the brand until they prove that they can create a lasting product that is also safe to use.

One last tip: I did a custom modification to the plates. I removed the two handles and put some masking tape around the edges of the plates. I then spray painted the plates with a black coloured extreme high heat resistant paint. The paint is usually available in most hardware stores. Pick the highest heat rated one and put several layers on the backside. This locked the oxidized layer inside and my hand/dishwasher never got soiled after that. ....until the ceramic coating chipped away duh. You take it or leave it, I'm done with this for good.


I agree that it is the heating element on the grill producing the black soot. Neither dish washing or handwashing makes it better or worse.


I believe it is the heating elements in the grill that are oxidizing... grill gets way hotter than dishwasher. Also the heating elements are covered in the same soot. I don't think there is a solution but wonder how safe it is to continue cooking with the unit.

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