A few surprising uses for eggshells

Bill Gates thinks a chicken is the best investment you can make. While he doesn’t go into too much detail on the nuts and bolts, you can imagine it’s more to do with egg production than a particularly satisfying rotisserie meal. But it’s not just the chicken or the egg that have value, the eggshell too can be useful. A great example of how a ‘waste product’ is really just another raw material.


Scratching at the surface

My partner’s brother keeps chooks in their backyard and it’s fun to watch them sunning and perching. Chickens are perhaps an under-appreciated one of design of nature – egg making machines powered by food scraps and pasture grubs. If I could, I’d keep chickens at home. In the meantime, I buy eggs laid by pasture raised chickens, or at the very least, free range chickens.

This is a long way from what I used to do, which was look for the cheapest food possible. It did me well as a uni student, where leftover cash could fund my drinking hobby, but my view on this started to course correct after reading the Omnivore’s Dilemma, and generally learning more about food production systems. I now buy the best quality food I can afford and pay attention to animal husbandry involved. And I drink less. #adulting

The chooks matched the house….and the (not pictured) elderly owner.

Shelling out for quality

I justify spending $6 – $10 a dozen on pastured eggs because I know they are better for me, the chooks and the environment. How the animals are raised impacts on the nutrition of their output.

Via Sustainable Table: Eggs from poultry raised on pasture have 10% less fat, 40% more vitamin A and 400% more omega-3’s.

After I use an egg, I hold on to the eggshells and store them in the freezer until I plan to use them, bothering no one except my partner. He once asked why I was storing garbage in the freezer and I had to gently remind him that there is no such thing as garbage. The eggshells, apple cores, celery bits and citrus peels are all raw materials just waiting for a good way to be used.

Here are a few ways eggshells are useful long after the nutritious interior is gone.

Use eggshells in the garden 

They can go directly into your compost bin or worm farm, or perform a little extra before you put them there.

eggshells for vermicomposting

Improve the soil In the soil, eggshells act as a slow release source of calcium, which helps to raise the PH of the soil (making it less acidic). Grind finely for best effect. Apparently this helps in vermicomposting if the bedding becomes too acidic. I have also read that the grit of the eggshells helps the worms, toothless creature that they are, to grind away at the food scraps.

Start a seedling There are plenty of ways to start seedlings – this Pinterest popular solution shows that half an eggshell can replace those small plastic punnets.

What aren’t they good for? Deterring slugs! According to this blog anyway (what you really want is diatomaceous earth).

Use eggshells in the kitchen

Clean the inside of a bottle Trust Tammy from Gippsland Unwrapped to find a Zero Waste and effective solution to a sometimes tricky task – cleaning out the grit from insides of bottles.

Clean a bottle with eggshells

It’s nice to know the minimalists among us could do away with a bottle brush. Since I already have a bottle brush, I use this trick whenever the brush doesn’t fit. Just add crushed eggshells and water into the bottle, and shake it like a Polaroid picture. It’s crazy how well this works.

Calcium supplementation Milkwood’s Kirsten Bradley adds an eggshell to water kefir ferments where it slowly dissolves over several batches. Each eggshell would have about 2000 – 2500mg of calcium, so you wouldn’t want to overdo the daily dose, especially if you’re getting a lot of calcium elsewhere in your diet or have heart issues. I don’t supplement calcium, but thought it an interesting way to achieve specific supplementation without the typically bottle and seal waste.

Use eggshells in…the bathroom?

Make tooth powder I make a tooth powder using calcium carbonate powder, clay, cinnamon, and sometimes bi carb or charcoal. I used to do the bi carb and coconut oil recipe, but it seemed a waste of oil and I didn’t like the idea of spitting oil into the drain pipes. All ingredients bought as refills from either the Soap Dispensary in Vancouver when I was there last year, or one of the bulk shops in Sydney. Since we don’t have a Soap Dispensary equivalent (tragedy really) in Sydney, finding a Zero Waste source of calcium carbonate could have proved difficult. Enter the ancient texts….

I’d read that ancient Romans used to grind eggshells for toothpowder. Clever, I thought, but I didn’t take action on this until I came across Zero Waste Chef’s post on making the same and then considered my lack of bulk calcium carbonate powder options.

How to find a good egg

  • If you can, buy or trade from someone you know. From a farmers market is a close second.
  • Watch out for misleading Free Range claims. In Australian, under current regulations, the stocking density can vary from 1,500 to 10,000 hens per hectare and no meaningful outdoor access. Animal welfare experts recommend 1,500. Sometimes this is listed on the carton, sometimes not. You can bet the cheapest free range eggs at the major supermarkets are produced with the max stocking density. More detail on the Choice website, including the names of brands that comply, those that don’t, and those that have been fined for lying.

How to tell if your egg is still edible

Australian eggs are often sold on the shelf, not in a refrigerated section. Once refrigerated, keep them there, but if they are not in the fridge when you buy them, there’s no real urgency in getting them into one, unless it’s really hot out or you plan to keep them for ages and ages. This also makes them handy for taking camping.

To see if your egg is still edible (and it probably is) you can check if it floats or sinks. Don’t eat a floating egg.

So give these ideas a crack or share in the comments any other uses you have for eggshells.