Are Scratched Coffee Mugs Safe?

Every now and then we come across something that we really like and over time, that item becomes our favorite. We develop some obsession with that item. Coffee mugs are not any different.

Most people have a favorite mug. Serve them the best coffee in a different mug and they will not appreciate it. Over time some scratches start forming on our favorite mugs and we are not sure whether we can still use the mug or we should retire it.

Are scratched coffee mugs safe?

Yes, scratched coffee mugs are safe to use unless the scratches are inside the mug and they run deeper into the mug’s material. Superficial scratches pose no safety issues and are easy to remove. Deeper scratches or crazing can leach harmful elements to your coffee depending on the material of the mug.

Inspecting the Scratches on Your Coffee Mug

All coffee mugs regardless of the material of the mug are susceptible to getting scratched. Sometimes, what appears to be a scratch is actually the scrapes from foreign objects such as metal deposits from a metallic stirrer.

Most scratches appear inside the mug especially on the bottom and the lower parts of the inner walls. Scratches on the outside of the mug are rare and even when present, they pose no risk.

To check whether the scratches are superficial or they run deep to the mug’s portion:

  • Add 2-3 tablespoons of baking soda with 1-2 tablespoons of fresh water
  • Mix to make a soft paste
  • Use a microfiber cloth to scoop some of the soft paste and gently rub it on the scratches. You may add a few drops of dishwashing soap to the paste
  • Rinse the mug in fresh water. The superficial scratches should be gone and the any cracks will be clearly visible

Should I Use a Cracked Coffee Mug?

A coffee mug that is cracked or chipped on the inside is not safe to use. Apart from the risk of bacteria flourishing in the cracks, the crazes or chips can grow into a bigger chip and the tiny shards from the new crazes may end up being ingested.

The exposed material of the mug can also leach harmful elements into the coffee. Let’s look at how cracks affect the different materials of mugs.

  • Ceramic Mugs. Ceramic mugs including, porcelain, Bone China, and Stoneware are usually glazed with a protective layer. Ceramic mugs with superficial scratches are safe to use as the scratches are usually on the surface of the glaze. However, in the case of cracks inside the mug, you are better off replacing the mug.
  • Plastic Mugs. Plastic mugs that are cracked should be retired as they may leach harmful elements to your coffee. The risk is even higher when cracked microwave-safe plastic mugs are used to heat coffee in the microwave
  • Metallic Mugs. They are very hard to crack under normal use. Metal flakes from stirrers may form inside the mug and appear like cracks. Cleaning the mug with a soft abrasive should remove the filings.
  • Enamel Mugs. These are probably the only mugs that look better when chipped. They have a unique rugged appeal, especially when used for camping. However, enamel mugs are not safe if they are chipped on the inside. Read our guide about making coffee when you don’t have a fire while bivouacking.
  • Glass Mug. Crazed glass mugs have a higher risk of shattering than other mug materials. Avoid using crazed glass mugs for coffee as you risk scalding yourself with hot coffee if the mug shatters.

What to Do with Cracked Mugs

Cracked handles on ceramic mugs can be fixed with food-grade ceramic epoxy. However, unless you are very sentimental about a coffee mug, you are better off replacing it if it’s cracked.

Instead of discarding a cracked mug, use it:

  • As a planter for your flowers or plants in the backyard garden
  • As a holder for your pens. You can decorate the mug with an inspiring message as use it to hold your pens
  • As a toothbrush holder especially for coffee mugs with beautiful art or message

What are the Black Lines Inside the Mug

Scratches inside the coffee mug can become black or brownish over time as coffee tannings adhere to the fine scratches. If the black lines are not cleaned, they can mask cracks that may form inside the mug.

To clean the black lines inside a mug:

  • mix one tablespoon of water with two teaspoons of baking soda to form a soft pulp
  • apply the mixture to the stained areas of the mug using a soft sponge. Let the baking soda stand for 5-10 minutes
  • use a sponge to gently rub the baking soda inside the mug
  • rinse the mug with clean water. Check if there are cracks inside the mug

Wrap up

Coffee mugs usually develop scratches over time but they are still safe to use. Crazing inside the mug may cause harmful trace elements from the leach into the drink.

The glaze is likely to chip around the crazed areas and the fragments can mix with the drink and end up being ingested.

You can use the cracked mug as a flower pot or a holder for pens or toothbrushes. You may decorate the retired mugs to increase their appeal and blend them into their newfound use.


Patrick is first a coffee lover and then a trained barista. His bucket list includes sky diving and sipping on Java in the Himalayas.

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