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I mentioned before about the AGA cooker that I had recently cleaned and the whole top had been painted with matt black heat resistant paint which didn't look good at all. It is normal for the whole AGA to be enamelled except for the ends of the towel rail on the front and the inside of the control panel door which is usually left bare metal but with the control instructions on an aluminium plate. So if you have an AGA that has been painted, I'm talking about the traditional AGA cooker here and not range cookers with an AGA badge, then it is unusual and I'd advise you to get the parts re-enamelled by an AGA re-enamelling company such as Hytech based in Highbridge in Somerset.
If its just the top which has been painted we can get it off but of course the damage underneath may mean it needs enamelling anyway.
When I bought my first AGA cooker in 1996 (it was a reconditioned enamel one) I noticed at the time there was a company which I think were called 'Country Cookers' who did reconditioned AGAs but they removed the enamel and then paint sprayed them with glossy paint. They looked good in the showroom but I have since cleaned one and they are a nightmare to clean as you can't get them back to as new standard like the proper enamel AGAs.
Also if you get a chip on your AGA I'd suggest you get an AGA enamel kit from AGA which will be the correct colour for your AGA.Google+