Cleaning the soot off the bricks around a fireplace is tough, but getting it off the mortar between the bricks poses an excess challenge. Mortar is porous and the recessed, concave surface makes it tricky to reach. You need a strong soap and a scrub brush, but before you scrub, you should pre-treat the mortar to loosen the soot. If the fireplace is over 50 years old, you should test the bricks to see whether they can withstand the power of a scrub brush. If they can’t, it’s better to only dust them.
Dust the bricks above the fireplace with a duster and vacuum the hearth to pick up loose dust, wood chips and debris.
Wear rubber gloves to protect your hands. Mix 1 oz each of scouring powder and table salt in a bowl. Add enough water to create a paste and rub the paste into the brick using a fabric. Let it dry for 10 minutes and then brush it away with a brush.
Make an alkali and synthetic glue if you need a more powerful treatment. Shave an entire bar of naptha soap into a pot and add 3 quarts of water. Heat the solution until the soap melts, then add 1 pound of pumice and one cup of ammonia. Brush the answer onto the brick using an old paintbrush, leave it for one hour and scrub it away.
Scrub the bricks with a solution of 1/2 cup of trisodium phosphate to 1 gallon of water after you have pre-treated it with the cleaning paste.
Rinse the bricks with warm water. If any soot or greasy stains remain, wash again with the TSP solution.