I hosted a cookie party this year excited to have the chance to use my kitchen aid stand mixer. After putting all of the ingredients into the bowl I started to attach the flat beater. My hands turned black! I still started the mixer because I thought it might be some oil from the connection but it turned out to be the attachment itself. We had to throw that batch away. There were lots of cookies to be made and no mixer. It was very disappointing! My wire wisk attachment also turns your hands black.