Have you ever wanted to test if your fruit and vegetables are really organic? Ever wanted to know if you've washed off all the nasty pesticides and fertilisers on that salad? The average human consumes up to two litres of pesticides every year, so litmus paper can be very useful in everyday cooking and of course, scientific experiments. Fortunately, making litmus strips yourself is very easy and cheap, and you can make as many as you want without having to repeat the process.
You will need:
Distilled Water (tap water works, just not as well)
Paper (acid-free, art paper works best)
Step 1: Break and Boil
Cut off as many leaves as you want, though you will probably only need about two or three. Then, place these leaves into a pot or deep saucepan. Then you can boil the distilled water, however make sure there is no water already in the kettle because this will contaminate the distilled water. Once the water has boiled, pour it into the pot. Cover the top of the pot with something, preferably a lid of some kind. This will speed up the infusion. Leave the infusion for about 15 minutes, but longer is better.
Step 2: Dip and Dry
The water should be dark purple-ish by now, if not leave it for a few more minutes. Place a few strips of paper in the post, before removing them with a glove and placing them on a large plate. You don't need to wear a glove, but distilled water is dangerous for your health if swallowed and it may still be hot. The strips shouldn't overlap, but you can dip as many strips as you like. Leave them to dry for an hour or so.
Step 3: Done and Dusted!
Your strips should be light blue/greyish. If not, they are either not fully dry or the infusion required more cabbage. If they are, congratulations! You have made litmus paper, ready for use on alkalis and acids. Alkalis will turn the litmus green, acids will turn it red. Be aware that you may need to leave the litmus to dry after a test to see the colour change. You also need to make a solution of the acid or alkali, a solid won't cause any change! This process can be performed with rhubarb instead of red cabbage, which turns brown in the presence of alkalis. This was my first instructable, so any feedback would be really helpful, and vote for the Build My Lab (Build Their Lab) contest would mean the world to me. Thanks, and follow me for more 'ables in the future! (•‿•)