I love eggs – they are one of nature’s miracle foods. But did you realise that the shells of eggs are an incredible resource too? They are so useful and versatile, they definitely deserve a place here on spotless. Here are ten ways to use them.

(Many uses for eggshells require them to be crushed. To do this, first dry them out. When you have collected a fair number, crush them. You can do this by hand, or by putting them in a bag and rolling with a rolling pin. You could also use a pestle and mortar, a blender or food processor, or a coffee, nut or spice grinder.)

In the kitchen

1. Eggshells are an excellent gently abrasive cleaner. You can use them to scour pots and pans. They are especially good at removing tea or coffee stains from cups, mugs, pots and thermos flasks. Crush the shells and toss some into the stained object. Dampen and leave overnight. In the morning add some water, swish around and pour down the drain.

2. The stains will be gone, but the eggshells will still be working for you, as they are also very good at cleaning drains. Leave some crushed eggshells in the drain basket of your sink from time to time and they will clean and clear as they make their way through your pipes.

3. Poke a hole in the bottom of an eggshell to turn it into a small makeshift kitchen funnel. The eggshell will filter out everything but liquid, and let it out in a thin stream.

On your skin

4. Eggshells can be dissolved in vinegar to form calcium acetate. Cover an eggshell with apple cider vinegar in a small jar and allow it to dissolve over a couple of days. (This will be quicker if you crush the eggshell first and mix well.) Use the liquid to treat skin irritations and itches.

5. Whisk powdered eggshells together with an egg white and use as a healthy calcium-rich facial mask that tightens the skin.

As a calcium supplement

6. Eggshells are 93% calcium carbonate (lime). This makes them an invaluable source of calcium. Eggshell calcium provides a healthy, balanced form of this essential element that is very easy for the body to absorb and digest. To prepare them, first wash the empty eggshells to remove all the egg white, but leave the membrane, which contains useful nutrients (this membrane has its own host of health uses, but that’s another post!) Dry the pieces thoroughly in the air and then grind them into a fine powder. Store them in a sealed container in a cool dry place.

Half a teaspoon (about one eggshell) of the powder represents about 400 mgs of elemental calcium, which is the daily amount required by most people. (If you need more, split up the doses.) Put this amount into a small dish and add the freshly squeezed juice of half a lemon. Mix well (it will fizz as the carbon is released). Leave it at room temperature for three to six hours. The longer you leave it the less gritty it will be, but do not leave for longer than 12 hours.

The resulting liquid is mainly calcium citrate, and can be taken by spoonfuls, washed down with a mouthful of water. It is best to take magnesium citrate at the same time as calcium. (Read more about calcium from eggshells here).

In the garden

7. Calcium carbonate from eggshells is also a great way to supply the soil with calcium, an essential plant nutrient necessary for growth. Growing plants remove large quantities of calcium from the soil, which needs to be replaced to keep them healthy and growing. Eggshells also contain small amounts of other useful substances such as nitrogen and phosphoric acid, making them an excellent fertiliser all round.

To add eggshells to your soil, sprinkle crushed shells around the base of plants.

8. Along with giving plants a boost, the eggshells also act as a pest deterrent. If not crushed too fine and still with plenty of jagged edges, a sprinkling of eggshells around vulnerable plants provides an impenetrable barrier against snails and slugs The crushed shells also deter cats and dogs from plant beds as they hurt their soft paw pads to walk on.

9. Eggshells also make perfect starter containers for seedlings. The calcium encourages growth and helps the small plants absorb other nutrients from the soil. And they are the perfect size! You can place your eggshell seedlings in the egg carton to make it easy to position them in a sheltered, sunny spot. When the seedlings are ready to plant out, just break the shells with your hand and plant them as they are.

In your coffee

10. Add an eggshell to your coffee grounds to make your coffee taste less bitter.

I was a bit dubious about this one when I first read about it. Then recently we were given some Ugandan coffee that was decidedly on the bitter side, so my husband gave it a try. At first, with just a few bits of eggshell, we couldn’t notice a difference. But then we tried a whole eggshell, and the result was quite incredible. The coffee was delicious, smooth and far less bitter! (We use a stove pot espresso pot and put the shells in the basket along with the grounds.) I was so impressed I did a bit more research. It turns out this is an old Scandinavian tradition (the egg white or even a whole egg is also sometimes added) and is also used when making “cowboy-style” camping coffee in a pot, to clarify the coffee and help the grounds settle. John Steinbeck wrote about using eggshells (and white) in his coffee in “Travels with Charley”, saying “for I know nothing that polishes coffee and makes it shine like that.” I’m not sure why this works, but apparently the alkalinity of the calcium-rich eggshells neutralises the acidity of the coffee. Anyway, I was impressed and will definitely be using this trick again.

As an added bonus, the mix of crushed eggshells and spent coffee grounds also make a convenient nutrient-rich combination to add to your compost, garden soil or a pot plant.