Cast Iron fireplace - pitted, how to remove

[rarara]

Going to spruce up one of the original victorian fireplaces in our house with blackener, but was looking for some advice first....

The bottom section (approx level with where the flames would normally be) is fairly pitted/corroded - there are no visible signs of rust below coming through the existing black coating, but it looks like this may have happened in the past. Should I be trying to get this back to smooth prior to repainting? And if so, with what?

Thanks

 

[Burnerman]

It's probably particles of free carbon that has burnt away in the past......do you intend to use the fireplace?
John

 

[rarara]

yes, am going to get it working again hopefully. the areas i am concerned about look like depressions where its seemingly (?) corroded away - maybe i need to adda pic when i get home later

 

[Burnerman]

Being a crude cast iron, it's actually the surface that has burnt away in places. I don't think you'll get anywhere trying to fill the indentations - maybe just call it 'character'!
John