The highest concentration of lead is usually in the paint on the outside of the Pyrex bowl or dish. With some very rare exceptions, the paint on the outside of both vintage Pyrex and vintage Corningware bowls and baking dishes will usually test positive for lead between 15,000 – 100,000 PPM lead.Click to see full answer. Similarly, you may ask, is corningware toxic?And then Corning sold their company in 1997 and they stopped making the Corning Ware material. But what was interesting about Corning Ware is that is a glass ceramics. So the one key factor of glass is it’s completely non-toxic, it’s somewhat durable, but it doesn’t heat very well.One may also ask, is corningware lead and cadmium free? Description. Some “glass” cookware is tempered with ceramic to make it more durable than just glass, but still just as safe. Corningware makes Visions (stovetop) and Pyrex cookware, both of which are considered glass cookware. Corningware is guaranteed lead-free. Herein, does blue cornflower corningware contain lead? Blue “Cornflower” Design Corningware Baking Pan: Lead-Free. Corning Blue Corn Flower Casserole, lead free! (non-detect for lead).Is vintage corningware valuable?”Vintage CorningWare” is considered to be pieces made prior to 1999, when the brand was sold to World Kitchens. A quick check of eBay reveals that most CorningWare pieces are priced between $5 to $60, however a Spice of Life 3/4-quart round casserole with lid is valued at $107.