re: Removing soot stains from fireplace mantle

I'd give TSP mixed in hot water a try.

Home Depot or Lowes have it in the paint section and it goes by the name Tri Sodium Phosphate in case you didn't know that already.

If you have tender skin on your hands, buy some rubber gloves.


Edited to add this: I've used TSP to wipe down ceilings in kitchens back in the day when most were painted with oil base high gloss paint.

I used it in one of my aunt's kitchens and both she and my uncle were heavy smokers and did so in their house. There was a HUGE difference in the color of the ceiling where it was wiped down with TSP and damn near white again as opposed to the yellow everywhere else.