This may not work very well with the IngenuiTEA, but for removing tough stains and buildup on smooth surfaces (even baked-on transfers from electric heating elements), Brasso will make short work of them all. Works on far more than just glass or plastic, too. It is a strong chemical mixture, though, so thorough rinsing is a must, though the stuff comes off very easily. Works better than anything else I've tried. But as I said, I think this is a less appropriate use for the technique.