we have an eyesore of a brick fireplace which takes up one whole wall in the family room and wraps around to the kitchen. the brick is not attractive and the mortar is dark grey/black. our house is already dark because of the lower ceilings and large, mature trees that block any natural light from coming in. paint seems like an easy fix, but prior to painting, i would like to somehow fill in the mortar lines to make it more flush with the brick to similate the "aged" brick look versus the perfect and deep grout lines of our 1970s brick. i got an estimate from a professional who was going to spread mortar over the entire surface to try to create the look I was going for, but it was out of my budget. i would like to do this myself. any suggestions? thank you!