Use Quick'n Brite cleaner. It is completely safe and works on brick and glass for soot and smoke. My fireplace was horrible and it took it right off. I got it at a home show but you can get it online at www.quicknbrite.com
Answer
Go to your local hardware store. They have all sorts of good products out there for cleaning your fireplace.
THERE ARE MANY AVAILABLE MASONARY CLEANERS.(BRICK OR STONE)ONLINE ;TRY SAVERSYSTEMS.COM -- THEY HAVE A LINE OF PRODUCTS NAMED DE-FY THAT WE USE ON A REGULAR BASIS. IF THESE DONT FIT YOUR NEEDS,THEN TRY SOME AMMONIA MIXED WITH WARM WATER ( 1 PART TO 3 RATIO) USE A SPONGE OR A WIRE BRUSH AND BE SURE TO WEAR RUBBER GLOVES. IF THAT STILL DOESNT FIT YOUR NEEDS,THEN TRY MURATIC ACID,AVAILABLE AT YOUR LOCAL HARDWARE STORE.BE SURE TO NUETRALIZE WITH A MIXTURE OF BAKING SODA AND WATER AFTER CLEANING WITH ACIDS!!! AFTER A GOOD CLEANING,YOU SHOULD THINK ABOUT SEALING THE MASONARY (BRICK OR STONE) WITH A SEALER TO HELP PROTECT IT FROM FUTURE STAINING AND OVERALL HELP EXTEND THE BEAUTY AND LIFE OF YOUR MASONARY WORK. SEALING ALSO MAKES FOR MUCH EASIER CLEAN UP NEXT TIME WITH A BASIC HOUSEHOLD DETERGENT AND WARM WATER.
Try using an art gum eraser. (Actually, you'll likely need several of them.) Often you can actually erase away soot and other residue right off the brick. Then use a vaccuum with a hose attachment to clean up the fallen dirty eraser bits.
This technique can also work well on tiles, or unfinished cedar and other wood surrounds. THIS WORKED JUST AWESOME, FOR THE COST OF ONE PINK PEARL ERASER AND THE HASSLE OF VACUUMING THE CRUMBS AFTERWARDS!!!!!
Just buy the hand cleaner the machanics use,(buy at any automotive supply )wipe it on the grout and bricks leave for a few minutes and wipe with clean clothe.Try some water and soap.
The absolute best cleaner for dirty brick fireplaces is T.S.P. It can be found at any hardware or home improvement store. A powder you just mix with water. It takes grease off of kitchen cabinets, use to wash walls, (especially a smokers room). So many. Try it.
PaverCleen when diluted with warm water will provide an economical high preformance cleaner. Grease, oil, and dirt are effectively removed from masonry and concrete surfaces especially fireplaces. A variety of additional surfaces such as bugs, mold, and other biological growths will be removed from steel, glass, and plastic.
Test all surfaces in an inconspicuous place prior to full application. Reference the Techincal Information (MSDS) for more information. http://www.pavercleen.com