If you want to clean your own stone fireplace instead of hiring a professional chimney sweeper, follow the method below.
For this, you will need some Tri-sodium phosphate, some bleach, some warm water, a bucket, a sponge, a stiff bristled brush, some old blankets or towels, a plastic tarp, some duct tape, a pair of rubber gloves, and eye protection.
1. Before you start, put on the rubber gloves and the eye protection and don’t take them off until you’re completely finished.
2. Make a mixture of tri-sodium phosphate and warm water in the bucket by following the directions on the label. If the fireplace is really dirty, then make a stronger solution.
3. For every gallon of solution you make, add about 2-3 ounces of bleach.
4. Place the plastic on the floor around the hearth to protect it. Tape its edges.
5. Put blankets and towels around the area to catch any runs, drips, and overflow while you work.
6. If the fireplace is seriously dirty, apply the solution with the sponge before you start scrubbing and leave it for a bit.
7. Start scrubbing with the scrub brush. It will require a lot of effort, as stone is very porous and the dirt has sunk in. The eye protection is essential here, as while you scrub, droplets of the solution will fly around. Try not to open your mouth, too.
8. If there are some stubborn stains, make a mixture of tri-sodium phosphate and water in the form of a paste and apply it directly on the stone. Scrub as much as you can.
9. Clean the stone with a wet sponge to rinse it.
10. When the stone is clean, leave it to air dry and only after that remove the blankets, the towels and the plastic tarp.
Don’t ever, EVER, try to clean a fireplace with a flammable liquid. It can’t be removed, and once you light the fireplace, it will pose a serious flame hazard.
Don’t use a lot of the bleach, as it will fade the colour of the stone.
If streaks appear, you have to use more water. Clean from the top to the bottom.
Just in case, before applying the cleaning solution, try it on a hidden spot and leave it for 24 hours just to see if it won’t harm the stone.
Always clean the fireplace when it’s cold. Don’t try to clean one which is heated or still in use.
Before cleaning the fireplace, scoop out all of the ash and fire debris, because they may just make a bigger mess.