They are only a temporary alternative, you will have to replace the bath or repeat the process in a couple of years. In my opinion not worth the effort of doing it for a steel bath and I think you will regret not doing it properly in the first place. Why would you need to knock tiles off to replace it.
I re-enamelled a cast bath around ten years back and it went very well and is still looking good as it is a rental i work on from time to time for the landlady. It is, like anything, all about good preparation although you do need to be DIY capable to a degree so take your time getting everything ready and it should turn out alright.
I used an enamel kit and it was applied with a roller and brush for the tricky bits around the taps and outlets. There are plenty out there such as this one....
Suitable for painting toilets, sinks, showers etc. Designed to coat surfaces above and below the waterline. Painting should be made in well ventilated room. Before painting thoroughly mix A and B components.
www.ebay.co.uk
Best shop around for what you need as prices vary.
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