Nordkalk: Finnish Quality – How to Choose the Right Lime for Your Chicken, Horse, or Mortar

If you've ever wondered why eggshells from one farm hit the pan with a satisfying crack, while another's crumble in your hands before they even reach the pot, the answer is often as simple as it is surprising: lime. Or, more precisely, the quality of the lime and how it's used. You see, there's one name in this country that has been doing this for decades, supplying everything from dairy barns and stables to construction sites – Nordkalk.

From my experience, the biggest issue isn't that people don't buy lime; it's that they don't always know which product is meant for which purpose. And that's not even mentioning the fact that lime isn't just lime. It's a raw material with hundreds of different uses, ranging from what you put in animal feed to what you mix into mortar when building a new home.

From Finnish rock to your chicken's bowl

When you walk down the aisle of an agricultural or hardware store and come across the section labelled Nordkalk, you know you're looking at a product that has been mined and processed right here in Finland, often from the finest Gotland or domestic limestone. It's pure, with a calcium content around 36 per cent, and most importantly – it contains no unnecessary additives. Animals need calcium for the same reasons we do: for skeletal development, nervous system function, and heart rhythm.

But what's the difference between, say, a bag of Nordkalk Ruokintakalkki 20kg and Nordkalk Aito kanakalkki 40 kg? It's simply the coarseness. The feed lime is ground to a fineness of about 1–1.5 millimetres. It dissolves quickly, making it ideal for mixing into feed for cattle, pigs, and horses, but also for chickens if you ferment their food yourself. Chicken lime, on the other hand, is coarser grit, about 3–6 millimetres in size. It dissolves more slowly, and that's precisely why it's the best option for laying hens.

• Feed Lime (1 mm): Fast solubility, suitable for horses, cattle, pigs, and chickens when mixed into porridge or wet feed.
• Chicken Lime (3–6 mm): Slow-release, helps maintain calcium availability throughout the eggshell formation process. Best offered in a separate feeder.
• Pullet Lime (3 mm): Coarser than feed lime but finer than chicken lime. Suitable for growing pullets.

When feeding chickens, it's worth remembering that calcium deficiency doesn't show up overnight. You notice it one day when a hen seems less energetic 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 grind is spot on, and there are no stones or impurities in the bag.

Construction lime is no joke

Now, let's look at the other end of the spectrum. When we talk about Sammutettu Kalkki Nordkalk Sl 90 30kg, we're no longer in the chicken coop; we're in a completely different world. This is proper construction lime, calcium hydroxide (Ca(OH)2), used to make mortar and lime paint. It's hydrated lime, produced by adding water to quicklime – a process that generates a strong exothermic reaction.

This is not a product to be taken lightly. As the product label warns, it irritates the skin and eyes and can cause respiratory irritation. But when used correctly, it's invaluable. It's also used for stabilising septic tank sludge. If you've ever wondered why old buildings have such healthy indoor air, one reason is precisely the lime mortar, which breathes and absorbs impurities.

Nordkalk SL 90 is often made from Gotland limestone, but it's processed in Finland. It is ground and hydrated to just the right consistency to produce a strong, durable mortar. For builders, it's a reliable choice when you want traditional durability.

Rocks and minerals – much more than just dust

When we talk about minerals, many people think of jewellery 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 – no matter what you call them, they are all part of the bedrock we stand on.

What's interesting is that we're now starting to understand the importance of the circular economy for these rocks. In the mining industry, there's a lot of talk about conflict minerals, but here in Finland, the focus has shifted to how we can reuse our own by-product rock and processed aggregates. The University of Oulu is currently running courses on geoconstruction and the circular economy, and the Continuous Learning Service Centre, Jotpa, has invested nearly three million euros in training to develop this very sector.

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

How to choose the right bag?

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

• For horses or large cattle: Nordkalk Ruokintakalkki 20kg, mixed into the feed or porridge.
• For laying hens: Nordkalk Aito kanakalkki 40 kg, offered free-choice in a separate feeder or mixed into homemade feed blends.
• For young pullets and chicks: Pullet lime (3 mm), which has enough coarseness but not too slow a solubility.
• For making mortar, lime paint, or sludge treatment: Sammutettu Kalkki Nordkalk SL 90 30kg, but remember to use protective gear.

And here's one final tip: if your chickens' eggshells have started to thin, you don't need any fancy additives. Get a 20-kilo bag of feed lime or chicken lime, and you'll be sorted. Dose about 100 grams for every kilo of feed, and calcium deficiency should no longer be an issue. In my own stable, I've noticed that regular Nordkalk supplementation even helps keep horses' hooves in better condition – because calcium isn't just for eggshells.

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