Things You'll Need
Ceramic cement, 200 grade
Large rubber band
Favorite coffee mugs naturally see a lot of use, often resulting in faded images and, sadly, cracks. Cracked ceramic is unsafe; it could cause leakage that could lead to mold, permanently ruining your mug. A sudden jar or clink also may turn the crack into a shattered mug. You can fix a cracked mug if you catch it early. Gentle hands and the right glue can turn that cracked mug into a working ceramic keepsake.
Spread out a layer or two of newspaper over your work surface. This protects the surface from glue damage and cushions your mug as you move it around.
Put on surgical gloves; rubber gloves work in a pinch, but surgical gloves protect your hands without sacrificing movement.
Place the mug on its side on the newspaper with the cracked surface facing up. Gently touch the tip of the utility knife to the crack.
Very slowly wiggle the knife back and forth to wedge the crack open a little. Work very slowly and gently; sudden movements could snap a piece out of the mug.
Squeeze a line of 200-grade ceramic cement into the crack. Remove the knife from the crack and gently press the crack closed with your hands. Some cement will squish out; wipe it away with a gloved finger or a slightly damp paper towel.
Wrap a larger-size rubber band around the mug to keep the crack tightly sealed. Allow the cement to dry for at least 48 hours. Remove the rubber band and allow the cement to cure for another 48 hours before using the mug.