After years of searing-hot blazes, fireplace mortar can crack, crumble, and fall out. Gaping mortar joints are not only unattractive, they leave the bricks more vulnerable to damage. So before wood-burning season starts, examine the condition of the mortar in the firebox and take an hour or two to replace any that has deteriorated. See How to Get Your Firebrick in Shape
for all the tools and steps you need.