I used soft scrub and a scrub brush, but I did it before there was anything there to mess up.

You can mask off anything beforehand with builders' paper, plastic bags, tape, layers of newspaper, etc.

I'd try strong soap and water first on a test area. Use three kinds of brushes: stiff short bristles, medium stiff long bristles and a couple of old toothbrushes.

However if that doesn't work, head to a fireplace shop and buy a hearth-cleaning product there. There are some fierce ones, based on lye. Use gloves and ventilation (if spraying it on, use a mask and goggles). Test in a hidden spot first to make sure it doesn't harm your mortar. Be patient, it's a pain to do. Don't saturate up too-large an area at once, even if it says to let it "work" for a bit. It will be time consuming and you don't want the stuff to dry out while you're working on another area. Have lots of paper towels on hand, and a bucket (not paper or plastic bag) to put the used ones in. They can easily mar other surfaces if they are wet after use.

HTH

L.

There just isn't any good way to do that 100% safely to you and the surrounding surfaces. There will always be a risk. Lirodendon described the safest DIY procedure, but you have to be very very careful.

This is where it pays to hire a professional. Call a couple of chimney swifts that have been in business for a long time and get some in person quotes while discussing your concerns.

Lay down a layer of plastic on the hearth, then cover it with several layers of newspaper.

For the painted bits, mask them with painter's tape and tape plastic over them.

"Soot" is an amazing blend of carbon and all kinds of resins and tars and volatile stuff from the wood (it's far more than just ash), so it's hard to remove. Use a product that is designed for removing soot - they can have obnoxious fumes (the one I use is ammonia based). Wear gloves and open windows.

Check the way you are making fires - position, size, and air supply because soot buildup usually means fire is too big or air-starved.