Coffee lovers know that the dark, rich drink can leave hard-to-remove stains on almost anything. If you’re a regular coffee drinker, it’s likely your cup, the coffee pot, the kitchen sink and even your smile have stains from coffee.
Even though coffee is chemically complex, researchers have found that the staining qualities largely relate to its acidic composition, this is why alkaline cleaning agents with a pH higher than 7 can help to combat discoloration.
When your coffee stains your household objects, there’s more to it than what meets the eye. Obviously, we know that coffee is the result of infusing hot water with the flavor of coffee grounds. According to the Specialty Coffee Association of America, the optimal cup of coffee is about 55 g per liter of water, which results in a ratio of about 1 part coffee to 18 parts water.
So, that one gram of coffee grinds, which obviously gets further diluted in the process of brewing when most of the solid matter is left behind, is packed with pigment that can easily stain household objects.
The coffee plant matter contains tannins, which are acids with a dark color that have an astringent quality, which wards off bacteria. Tannins add to the color of coffee as well as its flavor. Tea and wine both contain tannic acid as well. Tannins are used to dye materials like leather. In fact the pigment in coffee is so strong, it can be used as a natural dye.
In addition to tannins, coffee’s color is the result of melanoidins and carmels, which are pigment molecules formed during what’s known in chemistry as the Maillard reaction. The Maillard reaction occurs in foods when food proteins and sugars are altered by heat. Like tannins, melanoidins impact not only the color but the flavor of coffee, giving it its roasted flavor. Melanoidins exist in other roasted foods, too, like steak, potatoes and onions.
When the browning effect of the Maillard reaction takes place, the heat and moisture cause the complex sugars in food not only to break down, but also to form new bonds with other sugars and proteins, giving it a new flavor.
Whether or not these coffee pigments create a lasting stain will depend largely on the surface it touches.
Coffee stains can be removed a number of ways, but a few principles apply across the board. In general, a quick response to clean up the stain, and patience during the cleaning process will help you immensely.
If possible, rinse or dab the place coffee lands immediately with cold water and then follow up with your preferred cleaning agent. Whether it’s your shirt, the carpet or your cup, keeping coffee’s moisture from evaporating before you dilute it will prevent the stain from setting.
When a coffee stain dries, an interesting coffee-ring phenomenon occurs. As researcher Philip Ball notes, “the edge of the droplet (the contact line) gets ‘pinned’ at points on the surface,” creating a coffee ring.
Even though a coffee droplet disperses evenly across a surface, when it dries, particles move to the outer edge and compensate for the area where evaporation occurs first, but without disturbing the bounding line of the initial stain. This creates an uneven appearance, with a more concentrated line at the outer edge of the stain, which is consequently more difficult to remove than the lighter colored area.
Soaking a surface or fabric at least half an hour or even overnight can make all of the difference for reversing your coffee’s damage. This is because coffee contains water-soluble pigments.
Coffee stains are usually acidic in nature, so alkaline cleaning them with agents that have a higher pH value can often help remove the stain. That said, if alkaline cleaning products don’t work, you should attempt a vinegar or acidic solution, just in case.
If your first attempt at cleaning a coffee stain doesn’t work, try a different cleaning agent. Here is a list of useful cleaning agents for handling coffee stains:
One of the most common places you’ll find coffee stains is on stainless steel surfaces, including coffee pots, travel mugs like our Cruiser insulated tumbler and your stainless steel sink. Learn ways to eliminate coffee marks on stainless steel below.
It’s always disappointing when your favorite coffee cup loses its luster and starts to appear grimy and tainted from the residue of your daily coffee habit. With these cleaning strategies you can return your drinking vessel to its original condition. This particular solution is a slightly modified version of a recommended tactic from Good Housekeeping.
Supplies:
Step one:
Empty your cup of its contents. Add the hydrogen peroxide and baking soda--it will likely bubble up. Wait for the bubbles to settle and fill your cup to about a quarter inch from the brim with hot boiling water.
Step two:
Secure the lid, but not tightly. Gently shake or swirl the contents of the mug for 10-15 seconds.
Step three:
Leave the contents for 15 to 30 minutes. Soak longer for tougher stains.
Step four:
Pour the contents from the cup into the sink and rinse the inside with water. Gently wipe the inside of the cup dry. Now, your cup should be free of any stain or scent of coffee.
Remember: For vacuum insulated tumblers or cups, it’s best to avoid scrubbing coffee stains with abrasive steel or copper scourers. If you have a particularly tough coffee stain, simply soak your cup longer.
Just like your vacuum insulated travel mug, coffee stains can build up on your stainless steel coffee pot over time. You may be tempted to scrub or use bleach, but both methods will damage the smooth surface of your pot. Instead, use the gentler method mentioned above for your stainless steel tumbler. Or, you can try this alternate method from Healthcraft:
Supplies:
Step one:
Add baking soda, Hydrogen Peroxide and boiling water to the pot.
Step two:
Allow the coffee pot interior to soak for 45 minutes.
Step three:
Pour out the contents of the pot and rinse thoroughly with warm water.
Step four:
Gently dry the interior of your coffee pot with a cotton washcloth.
If scrubbing is required, start with some Bar Keeper’s Friend powder in your washcloth and gently scrub the interior of your pot. In this case, the powder, rather than the cloth, will do the scrubbing action. Then rinse the powder free and follow the baking soda and Hydrogen Peroxide instructions.
aBoth of the methods described will work on a stainless steel sink, but for tougher stains, you may want to try the scrubbing action of a baking soda and liquid dish-washing soap mixture, according to The Spruce.
Supplies:
Step one:
To create this mixture, don’t use water. Simply create a paste on your natural fiber or scratch-resistant cleaning cloth.
Step two:
Thoroughly scrub the interior of your sink.
Step three:
After scrubbing, rinse the perimeter and basin thoroughly with warm water.
Remember: Don’t scratch or scour the surface of your sink. If you pour out dishwashing fluid or other household cleaners that contain bleach into your sink basin, you may accidentally scratch the surface with the abrasive chemicals as well. Keep this in mind and avoid pouring anything that contains bleach into your sink.
For clothing or other household fabrics that can be washed in the washing machine, apply your stain-removing alkaline cleaner and allow it to soak the stain for half an hour before washing. The added wait will help dissolve the stain.
Remember to wash with cold water, because heat naturally causes stains to set in porous materials like fabric or even your teeth. Another thing to keep in mind is that some fabrics are more stain-prone than others.
In his research on how coffee interacts with different fibers, chemist Erik Kissa found that coffee sticks to different fabrics with varying tenacity: “Coffee stain has little affinity to polyester fibers but adheres to cotton and even more firmly to nylon.”
Therefore depending on what type of fabric fiber your coffee stains different cleaning agents may need to be employed, with nylon being the trickiest for stain removal.
For nylon, a stain remover containing bleach may be your only solution, but it will require care to avoid discoloring the dye used in the fabric. However, alkaline detergents and cleaners containing Hydrogen Peroxide or baking soda should work on polyester or cotton.
Apply Hydrogen Peroxide or OxyClean and allow the chemicals to remain on the carpet for roughly 30 minutes. When applying the solution, it is important to blot the surface of your carpet carefully with a damp, clean white cloth, to keep the stain from spreading and to protect your carpet from harsh scrubbing.
Keep in mind that if your carpet is nylon, for the reasons mentioned above, you may not be able to remove the stain without carefully applying a stain remover that contains bleach.
Not only does coffee stain our beloved cups, clothes and carpets, it can also follow us throughout the day when we smile. Coffee can stain your tooth enamel creating a yellow-ish hue that most people prefer to avoid.
Just as with all other cases of coffee stain cleaning, alkaline cleaning products tend to work best for removing teeth stains from coffee. According to Healthline all of the following supplies and tools and tips can improve your chances of keeping white teeth, even with a coffee drinking habit:
You may be tempted to brush your teeth right after drinking coffee. However, this can actually damage your teeth. By brushing after drinking or eating acidic substances, your tooth enamel can be degraded by the acids.
Other drinks that can stain your teeth include tea, wine, cola and artificially colored sports drinks.
Coffee naturally stimulates our mood and energizes us, but it helps to prepare wisely to avoid stains before you drink. If you get the jitters, try your best to maintain your composure and keep your coffee from spilling.
Even without spills, evidence of a coffee habit can build up on our teeth, cups, coffee pot and sink. Understanding the acidic chemistry behind coffee is the first step to tackling stains effectively. Remember to keep alkaline substances on hand.
When in doubt, apply baking soda. Not only does baking soda help remove coffee stains, it is not harsh enough to damage your kitchen or clothing supplies.
