Why You Can Trust CNET
Our expert, award-winning staff selects the products we cover and rigorously researches and tests our top picks. If you buy through our links, we may get a commission. Reviews ethics statement
There's a running joke in my family that centers around my older sister's absolute refusal to use a cup with ingrained coffee stains. Although a cup has clearly been washed thoroughly, she refuses to drink any liquid, even coffee, out of it. This provides fodder for fun jabs and inside jokes, but it did get me wondering: Why do coffee and tea stain all my cups, and why are the stains so hard to get rid of?
With these questions in mind, I fell down the rabbit hole of all things coffee stains. Below, you'll learn why coffee stains are so stubborn and five effective ways to fight them off. For more, learn how to remove stains from clothes, how to clean workout clothes and how to clean your running shoes.
Why does coffee stain your cups and mugs?
It's so frustrating to run your cups and mugs through the dishwater only to find they're still stained at the end of the cycle. Before you throw out that old cup, think of it as a learning opportunity to research why coffee has such powerful staining power.
Coffee can stain cups and mugs due to the presence of compounds called tannins, a type of polyphenol that is naturally present in coffee beans. When coffee is brewed, tannins can adhere to the surface of cups or mugs, leading to brown staining over time.
How to avoid coffee stains in your mugs
To stop stains before they start, it's best to rinse a cup or mug right after use to prevent any stains from setting in.
Additionally, coffee stains can be exacerbated by other factors, like the temperature of the coffee, since heat accelerates chemical reactions. The tannin compounds in the hot coffee will more strongly adhere to the cup material. Leaving the coffee in the cup or mug for an extended period also makes stains harder to remove since the tannins will set into the surface of the cup as the coffee cools down.
The porosity of the cup material can also impact the likelihood of staining. The more porous the material, the more susceptible it is to absorbing liquids and staining. Plastic, earthenware and stone cups or mugs are generally considered more porous. I recommend purchasing high-quality stainless steel cups or mugs since they're non-porous, making stubborn stains unlikely.
Regular cleaning of cups or mugs can help prevent coffee stains from ingraining into the material. Let's review some of the best methods for removing coffee stains.
5 methods to remove coffee stains for good
The following five methods should remove the coffee stains from your cups once and for all. (Or at least until the next time you drink coffee out of it, in which case, you'll need to repeat these steps.)
Method one
What you'll 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'll need: White vinegar.
What to do: Soak the coffee-stained cup in a mixture of white vinegar and water for a few hours. After, scrub the stains with a sponge or brush, and then wash the cup with dish detergent to eliminate the sour vinegar taste and its pungent smell.
Method three
What you'll need: Lemon juice and salt.
What to do: Make a mixture of lemon juice and table salt. Gently rub this mixture over the stained areas and then rinse thoroughly. You will want to wash the cup or mug with dish detergent and water afterward to get rid of any lingering lemon taste or smell.
Method four
What you'll need: Baking soda and white vinegar.
What to do: Sprinkle a few teaspoons of baking soda inside the cup or mug, gently pour in white vinegar and allow the mixture to fizz. Once it has fizzled out, scrub the stained areas with a sponge or brush and rinse thoroughly.
Method five
What you'll need: Denture cleaning tablets.
What to do: Denture tablets clean mugs just as well as they clean teeth. Fill the stained cup with warm water and drop in one denture cleaning 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.
With anything, a little effort and time will go a long way to making your cups and mugs shine. These tips will work on any drinkware material and can even be used for tea stains, too. Feel free to repeat any of the above processes as needed to get the stains out.
For more cleaning tips, you can also check out how often you should clean your makeup brushes, and the best way to machine wash your sheets and bedding.