How to Repair a Hairline Crack in a Coffee Mug – 5 Effective Methods to Fix Your Broken Coffee Mug

Have you ever got yourself in a situation where you find a hairline crack in your coffee mug while sipping your fresh coffee in the morning?

Even a minor looking hairline crack in your ceramic coffee mug is capable enough to send few coffee drops on your legs, hands or expensive clothes.

I know its not a pleasant experience at all.

And naturally we would either want to throw away that broken coffee mug or if it is precious to you, then obviously you would want to repair it any cost.

Today, I am going to talk about how you can repair a hairline crack in any type of ceramic coffee mug at your home.

There are 5 easy tricks which you can use to fix your broken ceramic coffee mug quickly and without much hassles.

So, I recommend you to read this article till the end to get to know all these interesting tricks.

Table of Contents

5 Simple Methods to Fix Your Broken Coffee Mug

Method 1: Boil in the Milk and Let it Soak in the Cracks

Yes, this is one of those unconventional methods which not a lot of folks easily try at home.

But believe me, you must try it first to see the results for yourself.

You will be surprised to see how milk protein acts as a natural glue when you boil your mug in the milk and let it soak for few hours.

Things You will Need:


Half liters of milk

High Temperature Resistance Electrical Tape

Your broken ceramic coffee mug

Actual Fixing Procedure:

1. First if there is a small hairline crack in the coffee mug, then you will need to apply a proper electrical tape on that crack accurately.

If there are lot of broken pieces, then you will have to first realign all the pieces the right way and then apply the electrical tape on all those cracks from the outside.

2. Here, the most important thing to remember is you should not use any other regular tapes to join the cracks of your coffee mug.

Because all those tapes will easily melt down in the hot milk. Only the right electrical tape will be able to withstand high temperature of hot milk.

3. Once you apply all the tapes on your coffee mug from the outside, you can place it now in the saucepan.

4. Pour the milk in that saucepan to fill it up completely. The coffee mug should be fully immersed in the milk.

5. Now boil the milk for an hour or so. The gas flame should be light or medium and not set on high to get the best results.

6. Once the boiling is done, its time to allow the milk to cool down completely. I highly recommend you to put the saucepan in the cool place for next 24 hours.

7. After the day is over or 24 hours are finished, take out the coffee mug from the saucepan and clean it properly.

8. Remove all the electrical tapes from the mug and you will now be able to see that the hairline cracks are filled up completely.

9. The main reason behind filling up those hairline cracks is the presence of milk protein.

There is a protein named as casein which gets separated on boiling of the milk and settles down again on nearby surfaces when the milk becomes cool.

This is how casein protein molecules are settled inside those hairline cracks of your broken coffee mug and acts as a natural glue for your mug.

10. In my opinion, this is the best method to fix the hairline cracks of your coffee mug because it is a natural glue and it will not be toxic or harmful for you when you drink coffee from the mug once it is repaired.

I strongly recommend you to watch the following video to learn this process with all the details.

Method 2: Using All Purpose Cyanoacrylate Glue

Several people have used this method successfully when it comes to fixing those hairline cracks of the ceramic mugs.

With the use of Cyanoacrylate glue such as Krazy Super Glue, you can quickly repair all broken coffee mugs at your home.

However, I recommend this method only when you have major cracks on the outer part of the mug and not on the inside of it.

Because this type of glue could be toxic in nature and will not be food safe by design.

So, use it only when you have very minor cracks on the outside of your coffee mug.

Things You will Need:

Krazy Super Glue

Broken coffee mug

Electrical Tape

Actual Fixing Procedure:

1. First realign all the broken pieces of your ceramic coffee mug.

2. Now get the Krazy Super Glue and start applying it slowly on those hairline cracks.

3. Make sure that you apply the glue a little more to soak it properly inside the cracks.

4. Now allow 1-2 minutes to soak the glue inside those cracks.

5. Once you see the remaining glue is started to dry off, you will need to wipe it off with a cotton cloth before it dries up completely.

6. Next, apply few electrical tapes on those cracks from the outside which will keep the glue in one place properly.

7. After this, keep the mug aside for few hours to let the super glue cure and soak inside the cracks the right way.

8. After 1-2 hours, you can remove the electrical tapes and see how the cracks are filled up completely.

9. And my friend, now your broken coffee mug is fixed entirely.

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Method 3: Using Low Viscosity CA Glue

Yes, this is another alternative option to use more effective Cyanoacrylate Glue to fix your broken coffee mug.

Such type of super glue is highly penetrating by nature.

This low viscous liquid glue will more efficiently seep inside the deep cracks of your coffee cup.

The best low viscosity Cyanoacrylate glue that I can recommend to you is Loctite 420 Instant Adhesive.

This adhesive is super-efficient in repairing smaller hairline cracks in your ceramic and plastic coffee mugs.

It is a high strength and fast setting super glue which can be used for all kinds of metals, plastic, ceramic, glass and rubber materials.

The fixing procedure is much similar to the above mentioned method no. 2.

Just follow this same procedure and you can obtain much faster and more efficient results in this method.

Click Here to Get Loctite 420 Instant Adhesive to Fix Your Broken Coffee Mug.  

Method 4: Using Japanese Kintsugi Repair DIY Kit

This is a widely popular ceramic material fixing method in Japan.

It is also getting a good popularity in US and European countries slowly and gradually.

Using this unique Kintsugi repair method, you can safely and naturally repair all types of hairline cracks of your ceramic coffee cups.

Things You will Need:

Kintsugi DIY Repair Kit

Wheat flour



Masking tape


Tea Spoon


Broken ceramic coffee mug

Actual Fixing Procedure:

1. First take a spoonful of wheat flour in a plate. Then add one spoon water in it.

2. Knead this mixture well with the spoon.

3. Now add a single spoon of Kintsugi Urushi liquid in the mixture that is included in your Kintsugi DIY Repair Kit.

4. Now knead the mixture till it becomes harder. Make sure that this mixture is consistent like a hair wax.

5. Now start applying this mixture properly on the broken edges of your coffee mug with the help of a spatula.

6. Make sure you apply the mixture completely on the inner and outer edges of the cracks so that it soaks in properly.

7. Apply this mixture similarly to the other broken parts of your ceramic mug.

8. Once you are done with the mixture, apply masking tapes on the joining parts properly.

9. Allow a day or two to properly soak all the adhesive inside the cracks of your coffee mug.

10. After that you can remove the masking tapes and clean the coffee mug with the water and then start using it to drink your coffee.

To learn this fixing process with the help of Kintsugi DIY repair kit, I recommend you to watch the following video.

Method 5: Using Food Safe Epoxy Resin Kit

This is my favorite method among all the above ones.

You can buy a good quality Epoxy Resin Kit online and use it to fix all the hairline cracks of your broken coffee mug in few easy steps.

The best thing about this product is that it is completely food safe, UV resistant, non-toxic and very easy to use at your home.

Things You will Need:

Epoxy Resin Kit

Masking Tape

And Your Broken Coffee Mug

Actual Fixing Procedure:

1. First you will need to take epoxy resin and hardener agent from two of the bottles that come in your Epoxy Resin Kit.

2. Take equal parts of both the ingredients and mix them well in the container for at least 3 minutes or more.

3. Once it becomes homogenous then apply it properly on the broken edges of your coffee mug.

4. Join the broken edges and apply the masking tape on those joining edges.

5. Now allow 1-2 hours to soak the adhesive properly inside the hairline cracks of your mug.

6. After that time period is over, you can remove the masking tapes, clean your coffee mug under the tap water and start using it to drink your coffee.

Final Thoughts

You can certainly fix your broken coffee mug at your home with the few simple tricks.

Repairing hairline cracks in your ceramic coffee mug is certainly possible by using effective super glue adhesives, Kintsugi DIY repair kit, Cyanoacrylate glue and with the help of Epoxy resin kit.

By using any one of these 5 efficient methods, you can fix all types of plastic, ceramic and glass coffee mugs or cups at your home even if there are multiple hairline cracks in them.

Finally, I wish you good luck if you are planning to fix one of your broken coffee mugs.


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