I am going to be moving into a new(to me) house soon, I close Tuesday, yay!

It has a cast stone fireplace surround/mantle.They were evidently very popular with the builder in my area.

It has a porous texture (think swiss cheese) that I do not like at all, plus has a few nicks etc. that need to be repaired. I cannot afford to rip it out and start over, not right now anyway.

I would like to fill in and smooth the finish, and paint it a nice white, the trim will be painted white also, and the wall behind will be gray.

What would you use? There are a couple youtube videos on faux finishes, but they really do not answer my question of what to use as filler/smoother.

I am going to have a local chimney sweep clean the chimney, repair a crack in firebox and install gas logs, so whatever I use needs to stand up to a little heat.

I have included a picture.