Key Concepts
Acids, absorption, bleaching, solubility

Introduction

It’s happened to most of us; you wear a brand new shirt to school or work, and in the middle of lunch, get a giant ketchup stain right in the middle of the shirt. Or maybe peanut butter. Or maybe spaghetti sauce. Whatever the stain is, it’s always ugly, and can be tricky to remove. Did you know that there are many different kinds of stains, and each requires different types of cleaning to get the stain out? If you try to clean a mustard stain using shower cleaner – 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!

This activity is not appropriate for use as a science fair project. Good science fair projects have a stronger focus on controlling variables, taking accurate measurements, and analyzing data. To find a science fair project that is just right for you, browse our library of over 1,200 Science Fair Project Ideas or use the Topic Selection Wizard to get a personalized project recommendation.

Background

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 blood or grass stains), oxidisable (stains like 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 (dissolves in water) chunks. Oxidisable stains are usually brightly colored, like wine or juice. These stains are removed by using a bleaching agent, such as 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 calcium and magnesium ions, breaking down tough dirt stains and allowing them to be washed away.

In this activity we will test the cleaning power of 3 different cleaning solutions made from household products. We will evaluate how well they clean 3 different types of stains. Keep track of your results, and maybe you’ll get to help with the laundry when you’re finished!

Materials

  • 3 Small Cups (3oz works well)
  • 1/8 cup White Vinegar
  • 2 tablespoons Cornstarch
  • 2-4 tablespoons Milk
  • 1/8 cup Hydrogen Peroxide
  • Non-Gel Toothpaste or Cream of Tartar
  • Water
  • A 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!
  • A black marker
  • Ketchup
  • Coffee or Tea
  • A teaspoon
  • Paper
  • Pencil or pen
  • A timer or clock
  • Access to a sink
  • Dishwashing gloves
  • A flat baking tray

Preparation

  1. Label your cups as follows: Cup 1 ‘Vinegar’, Cup 2 ‘Peroxide’, Cup 3 ‘Cornstarch’, Cup 4 ‘Water’.
  2. Pour your vinegar into the Vinegar cup.
  3. Pour the peroxide into your Peroxide cup. Add a ¼ teaspoon of cream of tarter or a non-gel toothpaste. Stir to combine.
  4. In the Cornstarch cup, combine your cornstarch and milk and stir to form a paste.
  5. Place your fabric on a flat, dry space (such as a counter top). If the surface under the fabric is not stain-proof, protect it with some newspaper or a flat pan.
  6. Use your marker to draw a row of 4 marks on the fabric. Make sure to leave at least 2 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 2 inches distance between the ink and the ketchup. Gently dab a small amount of ketchup in a 2nd row, next to the first ink row. Create a 3rd row using the coffee or tea, gently dropping a small amount of coffee next to each ketchup stain, again making sure to keep 2 inches between the ketchup and the coffee stains.
  7. Use your paper and pencil to create a table like the one below, to help you record your observations during this activity.

Cleaning Method

Ink

Ketchup

Coffee

White Vinegar

 

 

 

Hydrogen Peroxide Mix

 

 

 

Cornstarch + Milk

 

 

 

Control

 

 

 

Procedure

WARNING: This activity uses household chemicals that, if handled incorrectly, can be dangerous. Please have an adult help you!
  1. Start with your Vinegar cup. Use your teaspoon to carefully drop 1 teaspoon of vinegar across one row of different stains, so that you add a teaspoon of vinegar to 1 ink stain, 1 ketchup stain, and 1 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?
  2. Start your timer for 10 minutes.
  3. Rinse your teaspoon with water, then use it again to carefully drop 1 teaspoon of peroxide (from your Peroxide cup) across one row of different stains, adding a teaspoon of peroxide to an ink stain, a ketchup stain, and a coffee stain. Set your Peroxide cup down next to this row.
  4. Repeat step 3 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?
  5. When your timer goes off, put on your dishwashing gloves and carefully carry your stained fabric to the sink.
  6. 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.
  7. Gently squeeze any remaining liquid out of the fabric, and place it on the baking tray.
  8. 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.
  9. Look over your results and compare the cleaning solutions with the control stains. Does any cleaning solution have all 1’s? Does any cleaning solution have all 4’s? 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 3 different household products, to see how effectively they removed different types of stains from fabric. All of these products are excellent stain removers, however, they all work in different ways, and therefore they 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 molecules of the stain. 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 by water. Vinegar works well on dirt, mold and mineral deposits, as well as on other acid stains like coffee. Therefore, you may have found that 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 like ink, and in doing so it makes the stains colorless – but they’re still there! As a result, you may have found in your experiment 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 may have found that it did a good job with the ketchup stain on your fabric.

 

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Credits

Megan Arnett, PhD, Science Buddies

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Key Concepts
Acids, absorption, bleaching, solubility
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