The clay bar (I don t think) removes little or any of the paint or clearcoat finish. It is primarily used to remove surface bonded contaminents,and does it well. I reall y think if etching has taken place then to start with the absolute mildest of abrasive products would be the way forward. Have you tried a search in the detailing section.
Only my opinion based on experience when having to remove similar marks from the bonnet of a solid black lancia delta I had some years back, bearing in mind paint technology was nt quite as far forward as it is now and I doubt that lancia even had a clear top coat. I removed it never the less
mike