Nordkalk is Finnish Quality – How to Choose the Right Lime for Your Chickens, Horses, or Mortar

If you've ever wondered why eggshells from one farm crack firmly when you tap them on the pan, while another's crumble in your hand before they even reach the pot, the answer is often as simple as it is surprising: lime. Or, more precisely, its quality and how it's used. You see, there's one company in this country that has been doing this work for decades, whether for the barn, the stable, or the construction site – Nordkalk.

In my experience, the biggest problem isn't that people don't buy lime, but that they don't always know which product is meant for which purpose. Not to mention that not all lime is created equal. It's a raw material with hundreds of different uses, ranging from what you add to an animal's feed to what you mix into mortar when building a new house.

From Finnish Stone to the Chicken's Bowl

When you walk down the aisle of an agricultural or hardware store and come to the spot that says Nordkalk, you know you're looking at a product that has been quarried and processed right here in Finland, often from the finest Gotlandic or domestic limestone. It's pure, with a calcium content around 36 percent, and most importantly – no unnecessary additives. Animals need calcium for the same reason humans do: for bone development, nervous system function, and heart rhythm.

But what's the difference between, say, a bag of Nordkalk Feed Lime 20kg and Nordkalk Aito Chicken Lime 40 kg? It's simply a matter of coarseness. Feed lime is ground to a fineness of about 1–1.5 mm. It dissolves quickly and is therefore well-suited for mixed feed for cattle, pigs, and horses, but also for chickens if you're fermenting their feed yourself. Chicken lime, on the other hand, is a coarser grit, about 3–6 mm in size. It dissolves more slowly, and that's exactly why it's the best choice for laying hens.

• Feed Lime (1 mm): High solubility, suitable for horses, cattle, pigs, and chickens when mixed into mash or wet feed.
• Chicken Lime (3–6 mm): Slow-release, maintains calcium availability during shell formation. Offered in a separate container.
• Grower Lime (3 mm): Coarser than feed lime but finer than chicken lime. Suitable for growing pullets.

When it comes to feeding chickens, it's also important to remember that calcium deficiency doesn't show up overnight. It shows up when one day you notice a bird isn't moving with its usual energy, and the eggshell feels thinner. I've seen farms switch back to Nordkalk products simply because the quality of the feed lime is so consistent. The fineness is right on point, and there are no stones or impurities in the bag.

Construction Lime Is No Joke

Now, let's move to the opposite end of the spectrum. When we're talking about Slaked Lime Nordkalk Sl 90 30kg, we're no longer in the chicken coop, but in a whole different world. This is real construction lime, calcium hydroxide (Ca(OH)2), used for making mortar and lime paint. It's slaked lime, produced when water is added to quicklime – a reaction that generates intense heat.

This is not a product to mess around with. As the product label warns, it irritates the skin and eyes and can cause respiratory irritation. But used correctly, it's indispensable. It's also used for stabilizing septic tank sludge. If you've ever wondered why old houses have such healthy indoor air, one reason is exactly that lime mortar, which breathes and binds impurities.

Nordkalk SL 90 is often made from Gotlandic limestone as a raw material, but it's processed in Finland. It's ground and slaked to just the right consistency to create a strong and durable mortar. For builders, it's a reliable choice when you want traditional longevity.

Rocks and Minerals – Much More Than Just Dust

When people talk about minerals, many think of jewelry or ore deposits in Lapland. But the reality is much more everyday. Finland has an incredible variety of different rock types and minerals – mineral, agate, flint, alabaster, chert – whatever you want to call them, they're all part of the bedrock we stand on here.

What's interesting is that we're now starting to understand the importance of recycling these rocks. The mining industry is increasingly talking about the concept of conflict minerals, but here in Finland, the focus has shifted to how we can reuse our own waste rock and processed aggregates. The University of Oulu is currently offering courses on geo-construction and the circular economy, and the Jotpa Continuous Learning Center has invested nearly three million euros in training to develop exactly this field.

So, it's not just about sweeping up rock dust in the barn. This is about building the future, where minerals like dicopper chloride trihydroxide or even concretion-type iron and manganese deposits are given new life. And the best part is, the same principle applies at the farm level: when the eggshell is sound, it's a sign that the calcium cycle is working.

How to Choose the Right Bag?

If you're standing in front of the store shelf wondering which one is right for you, follow this logic:

• For horses or large cattle: Nordkalk Feed Lime 20kg, mixed into feed or mash.
• For laying hens: Nordkalk Aito Chicken Lime 40 kg, offered free-choice in a separate container or mixed into a homemade feed blend.
• For young pullets and chicks: Grower Lime (3 mm), which has enough coarseness without being too slow to dissolve.
• For making mortar, lime paint, or sludge treatment: Slaked Lime Nordkalk SL 90 30kg, but remember your protective gear.

And one final tip: if your hens' eggshells have started to thin, you don't need any fancy additives. Get a 20 kg bag of feed lime or chicken lime, and you're good to go. Dose about 100 grams for every kilogram of feed, and calcium deficiency should no longer be a problem. In my own stable, I've noticed that regular feeding with Nordkalk also helps keep horses' hooves in better condition – because calcium isn't just for eggshells.

Finland is fortunate to have its own lime industry that understands this country's soil and the needs of its animals. It shows in every bag. When you buy domestic, you know what you're getting.