soft center section of steel foof cars.

[J Franklin]

You will eventually have to replace the top, but with that said top dressing was a tried and true fix for worn and dingy tops back in the day. It depends on how you use or show your car wether or not to use a coating. I see black rubber in spray or brush form on TV ads all the time. Just do a good job of masking things if you decide to use something on the top.