[Bill Douglas]

Hi Guys, my kid sister has an expresso maker that has developed white oxidising on the inside. It's a bit like the stuff we get on our bumpers. I've tried cleaning it off with things like baking soda and oven cleaner, but nothing seems to budge it. I'm tempted to put some caustic soda (lye) into it and dive for cover, but I'm concerned the remaining traces of it might be a bit toxic?

Any thoughts, or other ideas?