Laundry lab

Detergents are supposed to remove stains, and you can find out how well by carrying out washing tests. But each stain can only be washed once, right? So how can I make comparisons between detergents and find out which conditions are best for removing the stains? The answer is, before I wash, I first need to make multiple pieces of fabric dirty. The experts call this "staining". In this experiment, we want to show you the principle of how the professionals do it, so we won't use real detergent. Instead, you can use a little dishwashing detergent.

Before you get started

If you are experimenting at home:
1. Let your parents know and discuss the experiments with them beforehand.
2. Do not eat or drink at your workspace.
3. Wash your hands thoroughly before and after the experiment.
4. Be careful and cautious with the materials.

Graphic figure boy pouring liquid in flask

white fabric, measuring jug, blue liquid detergent and jar containing blue berries

You will need

Equal-sized pieces of cotton fabric ‏(for example, from old white undershirts)
Something to make a stain – for example, beet juice, cocoa and lipstick
Cold and warm water
Container for washing
Dishwashing detergent
Stopwatch
Spoon for stirring

Let’s get started!

hand applying red lipstick on white fabric

1. Staining

Cut out four equally sized square pieces of fabric from an old white T-shirt. Stain each piece of fabric in the same way, making sure that each type of stain is applied to the piece of fabric a total of three times and that the stains do not touch each other. The stains should all be the same size.

blue symbol for thermometer and clock symbol, quater of an hour

2. Test no.1 – cold water

Take the first piece of cloth and put it in a large glass or washing bowl. Add 0.7 l of cold tap water and stir for 5 minutes. Then take out the piece of cloth and wring it out well.

blue symbol for thermometer and clock symbol, half an hour

3. Test no. 2 – cold water, long wash

Take the second piece of cloth and place it in a large glass or wash bowl. Add 0.7 l of cold tap water and stir for 10 minutes. Then take out the piece of cloth and wring it out well.

blue symbol for thermometer, clock symbol, quater of an hour, and symbol for foam

4. Test no. 3 – cold water and dishwashing detergent

Take the third piece of cloth and place it in a large glass or wash bowl. Add 0.7 l of cold tap water and half a teaspoon of dishwashing detergent and stir for 5 minutes. Then take out the piece of cloth and wring it out well.

red symbol for thermometer and clock symbol, quater of an hour

5. Test no. 4 – warm water

Take the fourth piece of cloth and place it in a large glass or wash bowl. Add 0.7 l of cold tap water and stir for 5 minutes. Then take out the piece of cloth and wring it out well.

6. Evaluation

Place all four pieces of fabric next to each other and try to answer the following questions:
Do all the stains wash out equally well (or poorly)?
Which test produced the best result?
Which test produced the worst result?
How could the experiments be improved?