It’s happened to most of us: You wear a brand new shirt, and in the middle of lunch you get a giant ketchup stain right in the middle of it—or maybe it’s peanut butter or spaghetti sauce. Whatever the stain, it’s always ugly and can be tricky to remove. Did you know there are many different kinds of stains and each requires different types of cleaning to get it out? If you try to clean a mustard stain using shower cleaner, for example, you probably won’t get good results. Why does the type of stain matter? In today’s activity we’ll explore a few different kinds of stains—and try to determine the best method for cleaning them!
There are many different types of household cleaners because there are many different types of messes to clean up! Stains can be roughly grouped into four different categories: enzymatic (such as grass or blood stains); oxidizable (stains such as coffee or tea), greasy (butter or oil) and particulate (your typical, run-of-the-mill dirt stains).
Enzymatic stains are generally the result of protein action, and therefore enzyme cleaners will help break down these proteins into smaller, soluble (able to dissolve in water) chunks. Oxidizable stains are usually brightly colored, such as juice. These stains are removed by using a bleaching agent, for example, hydrogen peroxide. These oxidizing agents break down the color-causing components of chemical structures so that the stain becomes invisible! In the case of greasy stains the best cleaners are usually surfactants. Surfactants surround the greasy stain and expose the water soluble sections of the stain-causing chemical structure helping it to dissolve in water and wash away. Finally particulate stains are usually cleaned with compounds called builders. These builders help remove positive metal ions such as those of calcium and magnesium, breaking down tough dirt stains and allowing them to be washed away.
In this activity we will test the cleaning power of three different cleaning solutions made from household products. We will evaluate how well they clean three different types of stains. Keep track of your results, and maybe you’ll be able to add some science to the laundry when you’re finished!
- Three small cups (three-ounce size works well)
- One eighth cup of white vinegar
- Two tablespoons of cornstarch
- Two to four tablespoons of milk
- One eighth cup of hydrogen peroxide
- Nongel toothpaste or cream of tartar
- Piece of light-colored fabric that can be stained (such as a cleaning rag) (Make sure to ask for permission from an adult before choosing your fabric!)
- Black marker
- Coffee or tea
- Pencil or pen
- Timer or clock
- Access to a sink
- Dishwashing gloves
- Flat baking tray
- Adult helper (This activity uses household chemicals that, if handled incorrectly, could be dangerous. Have an adult help you!)
- Label your cups as follows: Cup 1 “Vinegar,” Cup 2 “Peroxide,” Cup 3 “Cornstarch,” Cup 4 “Water.”
- Pour your vinegar into the vinegar cup.
- Pour the peroxide into your peroxide cup. Add one quarter teaspoon of cream of tartar or a nongel toothpaste. Stir to combine.
- In the cornstarch cup combine your cornstarch and milk and stir to form a paste.
- Place your fabric on a flat, dry space (such as a countertop). If the surface under the fabric is not stainproof, protect it with some newspaper or a flat pan.
- Use your marker to draw a row of four marks on the fabric. Make sure to leave at least two inches between each mark, and try to keep them all in a line. Next to each mark on the fabric make another small stain using ketchup, keeping at least two inches distance between the ink and the ketchup. Gently dab a small amount of ketchup in a second row next to the first ink row. Create a third row using the coffee or tea, gently dropping a small amount of coffee next to each ketchup stain, again making sure to keep two inches between the ketchup and the coffee stains.
- Use your paper and pencil to create a table with four columns and five rows. In the first row label the columns: “Cleaning Method;” “Ink;” “Ketchup;” “Coffee.” In the first column label the rows: “White Vinegar;” “Hydrogen Peroxide Mix;” “Cornstarch and Milk;” “Control.” This table will help you record your observations during this activity.
- Start with your vinegar cup. Use your teaspoon to carefully drop one teaspoon of vinegar across one row of different stains, so that you add a teaspoon of vinegar to one ink, one ketchup and one coffee stain. Set your vinegar cup down next to this row. Did anything change when you added vinegar to the stains? Which stain is the darkest? Which is the lightest?
- Start your timer for 10 minutes.
- Rinse your teaspoon with water, then use it again to carefully drop one teaspoon of peroxide (from your peroxide cup) across one row of different stains, adding a teaspoon of peroxide to an ink, a ketchup and a coffee stain. Set your peroxide cup down next to this row.
- Repeat this step again gently dropping your cornstarch paste onto one of each stain. (If the paste has hardened, add a small amount of milk and stir.) What do you notice about the cornstarch and milk mixture? Is the consistency different than the other cleaning methods you’re testing?
- When your timer goes off, put on your dishwashing gloves and carefully carry your stained fabric to the sink.
- Rinse each stain for 10 seconds with cold water, including the row of untreated stains. Use your fingers to gently rub the fabric as your rinse the stain.
- Gently squeeze any remaining liquid out of the fabric, and place it on the baking tray.
- In your table, rank the ink stains from darkest to lightest. The most faded stain should be a 1 and the least faded stain should be a 4. Do the same for the ketchup and coffee stains.
- Look over your results and compare the cleaning solutions with the control stains. Does any cleaning solution have all 1s? Does any cleaning solution have all 4s? Did a cleaning solution work well for one type of stain but not for others? Overall, which cleaning solution worked best? Which one worked the worst? Was one of the stains more difficult to remove than the others?
- Extra: Repeat this activity testing other household products and foods that commonly cause stains. For example, mustard or cooking oil. Compare your results.
- Extra: Test whether leaving the cleaning solutions on the stain for a longer period of time changes your results.
Observations and results
During this activity, you experimented with three different household products to see how effectively each removed different types of stains from fabric. Although all of these products are excellent stain removers, they each work in a different way and therefore are most effective with different types of stains.
To start, vinegar works as a very effective household cleaner because it is an acid. Acids remove stains and clean by adding a chemical charge to the stain’s molecules. Much like a magnet being pulled by another magnet, these newly charged molecules become attracted to the positive and negative charges in water. As a result they pull away from the fabric and can be rinsed away with water. Vinegar works well on dirt, mold and mineral deposits as well as on other acid stains including coffee. Therefore, you may have found vinegar did a good job removing your coffee or tea stain.
Hydrogen peroxide works differently than vinegar and is better at removing different types of stains. Hydrogen peroxide doesn’t actually remove stains—it just makes them invisible! It breaks up strong chemical bonds in stains including ink, and in doing so it makes the stains colorless—but they’re still there! As a result you might have found in your tests that peroxide did the best job of “removing” the ink stain.
Finally, cornstarch works well as a stain remover because it attracts and absorbs the molecules of the stain. Cornstarch works especially well on grease stains and food stains, so you might have found it did a good job with the ketchup stain on your fabric.
More to explore
The Chemistry of Clean: Make Your Own Soap to Study Soap Synthesis, from Science Buddies
Cabbage Chemistry—Finding Acids and Bases, from Scientific American
Going Green as You Clean: Are “Green” Detergents Less Toxic Than Conventional Detergents?, from Science Buddies
Science Activities for All Ages!, from Science Buddies
This activity brought to you in partnership with Science Buddies