Right, I no longer have ironstains on my bath. Incidentally, the top glaze layer is the one that had gone below a tide-line, and the absence of which has led to all this activity. It's absence is due to the actions of a previous occupant. I don't know what they did, or what liquid they had in the bath, but they tried to cover the dull surface with some painty product of which very little remained when I moved in, and had itself been scraped. At least that explains why I can't get it back to original gloss. Thanks for the background, John. I'm using the car polish to protect the new shine, so the vulnerability to new stains should be under some control.

I used a copy of Coke which I found in the garage while looking for the oxalic acid, which I am now quite worried about. It isn't where I originally put it, in the kitchen. I remember deciding to move it away from food (it was somewhere I had to stand on a step ladder and move things to get to, but I decided to be safer.) It isn't with cleaning things under the sink. I have yet to look in the store cupboard near the front door with my tools and rock collection. It isn't in the garage with the potassium permangate. But there I found a small Cola can which I had bought a couple of years back for a friend who didn't drink it. Still sealed, but partly empty. Strange. It didn't work easily, but with a little encouragement from the abrasive, I have a whiter bath. Neither it, nor the paper worked alone. Thanks Micca.

I have now discovered a hairline crack in the enamel. I think this is due to over-hot water when my thermostat went wrong a while back. Any ideas?

Penny