I&#x27;ve been looking into this Sharpie mug 350 degrees craft and it looks as though many people have been experiencing fading or the colors coming off altogether. Therefore, I would like to share this blogger&#x27;s page. She explains to the tee how she cooked her mug at 425 for 30 minutes and then left the mug to cool in the oven. The results: a permanent cup at last! -- good because I did this once at 350 and the sharpie washed off!