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 tap firmly on the pan, while those from another crumble in your hands 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 correctly. You see, there's one player in this field that has been doing this work for decades, supplying barns, stables, and construction sites alike – Nordkalk.

From my experience, the biggest issue 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 the same. It's a raw material with hundreds of different uses, from what goes into an animal's feed to what's mixed into mortar when building a new house.

From Finnish Stone to the Chicken's Dish

When you walk down the aisle of an agricultural or hardware store and spot the Nordkalk section, you know you're looking at a product that's been quarried 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 – no unnecessary additives. Animals need calcium for the same reasons we do: for bone 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 mixed feed for cattle, pigs, and horses, but also for chickens if you're fermenting their food yourself. Chicken lime, on the other hand, is a coarser grit, about 3–6 millimetres in size. It dissolves more slowly, and that's exactly why it's the best choice for laying hens.

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

When feeding chickens, remember that calcium deficiency isn't immediately obvious. 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 spot on, and the bag contains no stones or impurities.

Construction Lime is No Joke

Now let's go to the other extreme. 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 for making mortar and lime paint. It's slaked lime, produced when water is added to quicklime – a vigorous reaction that releases heat.

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

Nordkalk SL 90 is often made from Gotland limestone as a raw material, but it's processed in Finland. It's ground and slaked to just the right consistency to produce strong, long-lasting mortar. For builders, it's a reliable choice when seeking traditional durability.

Rocks and Minerals – Much More Than Just Dust

When minerals are mentioned, many think of jewellery or ore deposits in Lapland. But the reality is much more everyday. Finland has an incredible variety of rock types and minerals – minerals, agate, flint, alabaster, chert – no matter what you call them, they are 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 materials. In the mining industry, there's increasing talk about conflict minerals, but in Finland, the focus has shifted to how we reuse our own waste rock and processed aggregates. The University of Oulu is currently running courses on geo-construction and the circular economy, and the Continuous Learning Service Centre Jotpa has invested nearly three million euros in training to develop this very field.

So, it's not just about cleaning stone dust out of the barn. This is about building for the future, where minerals like dicopper chloride trihydroxide or 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 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 at the shop wondering which product is for you, follow this logic:

• For horses or large cattle: Nordkalk Ruokintakalkki 20kg, mixed into feed or mash.
• For laying hens: Nordkalk Aito kanakalkki 40 kg, provided freely in a separate container or mixed into a homemade feed blend.
• For young pullets and chicks: Grower lime (3 mm), coarse enough but without overly slow solubility.
• For making mortar, lime paint, or treating sludge: Sammutettu Kalkki 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 potions. Get a 20-kilo bag of feed lime or chicken lime, and you're sorted. Dose about 100 grams for every kilogram of feed, and calcium deficiency should no longer be an issue. In my own stable, I've noticed that regular Nordkalk feeding keeps the horses' hooves in better condition too – because calcium isn't just for eggshells.

In Finland, we're fortunate to have our own lime industry that understands the country's soil and the needs of its animals. That's evident in every bag. When you buy local, you know what you're getting.