I did a fabulous job on a friends fireplace. First I used a water-based primer to hide all the scuffs and ash. Then I used a nuetral biege color and covered the brick completely grout and all. I went over that with sponging bits of brick red and moss green very lightly only on the brick surface not the grout. you can use what ever colors you like. Then using a several rags I white-washed the entire finish with 1/2 cream color latex and 1/2 water. I white-eashed on an area about 2ft x 2ft then wiped it off. It came out incredible! Looks so real the owners couldnt believe that their boring white fireplace could look that good. Good luck and I will try to get a picture soon!
"I can do anything I put my mind to!" Robin Mathews