There is a running joke in my family that centers around my older sister’s adamant refusal to use a cup or mug with ingrained coffee stains. Although one glass had obviously been thoroughly washed, she refused to drink any liquid – even coffee – from it.
This provides fodder for funny jabs and inside jokes, but it got me wondering: why do coffee and tea stain all my mugs, and why are the stains so hard to remove?
With these questions in mind, I delved into the wide world of coffee stains. I set out to find a solution to prevent stains from building up on my cups, mugs, thermoses and coffee pot, and I can confidently say that I can now get my sister to drink from any cup. Below, you’ll learn why coffee (and tea) stains are so stubborn and five effective ways to combat them.
Read more: Learn how to remove stains from clothes, how to clean workout clothes and how to clean your sneakers.
Why does coffee stain your cups and mugs?
It is so frustrating to run your glasses and mugs through the wash water only to find they are still stained at the end of the cycle. Before you toss that old cup, think of it as a learning opportunity to explore why coffee has such powerful coloring power.
Coffee can stain glasses and mugs due to the presence of compounds called tannins, a type of polyphenol naturally present in coffee beans. When coffee is brewed, tannins can stick to the surface of cups or glasses, causing a brown coloration over time.
How to avoid coffee stains in your cups
The best offense is a good defense. To stop stains before they start, it’s best to rinse a glass or mug immediately after use to prevent stains.
Also, coffee stains can be worsened by other factors, such as the temperature of the coffee, as heat speeds up chemical reactions. The tannin compounds in hot coffee will stick more strongly to the cup material. Leaving the coffee in the cup or mug for an extended period of time also makes the stains more difficult to remove because the tannins will harden into the surface of the cup as the coffee cools.
The porosity of the cup material can also affect the likelihood of staining. The more porous the material, the more susceptible it is to liquid absorption and staining. Plastic, clay and stone cups or glasses are generally considered more porous. I recommend purchasing high-quality stainless steel mugs or mugs as they are non-porous, making stubborn stains unlikely.
Regular cleaning of glasses or mugs can help prevent coffee stains from penetrating the material. Let’s review some of the best methods for removing coffee stains.
Five methods to remove coffee stains for good
The following five methods should remove coffee stains from your mugs once and for all. (Or at least until the next time you drink coffee from it, in which case you’ll have to repeat these steps.)
Method one
What you will need: Baking soda and water.
What to do: Create a paste by mixing equal parts baking soda and tap water. Apply the paste to the stained areas of the cup, scrub gently with a sponge or brush, then rinse thoroughly.
Method two
What you will need: White vinegar.
What to do: Soak the cup with coffee stains in a mixture of white vinegar and water for several hours. Then scrub the stains with a sponge or brush and then wash the glass with dish soap to remove the vinegar’s sour taste and pungent smell.
Method three
What you will need: Lemon juice and salt.
What to do: Make a mixture of lemon juice and table salt. Gently rub this mixture on the stained areas and then rinse thoroughly. You’ll want to wash the glass or mug with dish soap and water afterwards to get rid of any remaining lemon taste or smell.
Method four
What you will need: Baking soda and white vinegar.
What to do: Sprinkle a few tablespoons of baking soda into the mug or glass, carefully pour in white vinegar and let the mixture fizz. Once it’s gone, scrub the stained areas with a sponge or brush and rinse thoroughly.
Method five
What you will need: Tablets for cleaning prostheses.
What to do: Denture tablets clean cups just as well as teeth. Fill the stained glass with warm water and drop in one denture cleaner tablet, making sure to add enough water to completely cover the coffee stains. Let it sit for a few hours and then scrub and rinse as with the other methods.
As with anything, a little effort and time will go a long way in making your glasses and mugs shine. These tips will work on any dishware material and can even be used on tea stains. Feel free to repeat any of the above processes as needed to remove stains.
For more cleaning tips you can also check out how often should you clean your makeup brushesand the best way to machine wash your sheets and bedding.
Frequently asked questions
What causes coffee stains on cups?
Compounds called tannins are present in coffee beans, and when these beans are brewed, the tannins begin to stick to the surface of glasses, cups, and other vessels they come in contact with.
Why do stainless steel cups get dirty less?
One of the factors that determines how much tannin sticks to your glass is how porous the vessel is. Plastic, clay and stoneware cups will absorb these tannins and discolor very quickly. High quality stainless steel is much easier to clean as tannins are less likely to stick to surfaces.
