The discovery of stone wool
Stone wool is a natural product. It is made from basalt, solidified lava spewed from the innermost depths of the earth. In the mid-nineteenth century, American geologists on Hawaii discovered a “woolly” material consisting of stone threads, which the local inhabitants were using to insulate their huts. This was a volcanic material, the product of red-hot steam being forced through liquid lava under high-pressure.
To manufacture stone wool commercially, the ROCKWOOL Group duplicated this natural process as closely as possible. Today, extracted basalt is re-liquefied in furnaces at a temperature of 1,500 °C. The liquid Basalt is then spun into threads in spinning chambers, and then congealed in a hardening kiln using hot air (230 °C) and compressed into wool packets, which are then cut into slabs, blocks or plugs and packaged in film. With factory processing, one cubic metre of basalt can produce approximately fifty cubic metres of stone wool.
The invention of stone wool substrates
During one of the ROCKWOOL Group stone wool insulation production rounds, some ingredients were left out. This led to faulty products rolling off the production line. These products were placed outside as waste material. When the material was collected not too long after, the production workers were surprised to see little plants growing on the stone wool. This sparked an idea that led to intensive research together with universities and eventually the establishment of GRODAN Group in 1969. Stone wool substrate cultivation was the perfect solution at a time when many objections were being raised regarding the exhaustion of arable land. Not only did GRODAN products completely replace soil, crops also proved to grow extremely well on this growing medium, significantly increasing crop yield. Since then, The GRODAN Group has had a strong focus on innovation, developing its Precision Growing solutions to enable closed cultivation systems and to ensure that water, nutrients, energy and space are used in the most efficient way possible.
Stone wool benefits
Stone wool is a natural product consisting of a volcanic rock called basalt. Use of stone wool has many benefits for the professional grower:
- Thanks to the controlled manufacturing process, this growth medium is of a consistently high quality. Sterile production at extremely high temperatures guarantees a clean product with no pollutants, free of plant diseases.
- Additionally, stone wool enables recirculation of water and nutrients, so there is no waste of input materials.
- Plants grow easily and well on this growing medium. The plant has all the room to root in and develop optimally in this airy growing environment.
- Its unique hydrophilic fibremakes the cultivation on stone wool substrate very easy to control. All the water and nutrients administered to the plant are available to the plant.
- Stone wool substrate does not lock up or release any substances, enabling the grower to apply precisely the right amount of water and fertiliser and thus optimise the growing result. Waste becomes a thing of the past.
- Efficient use of water and nutrients keeps yield per square metre high, and energy consumption per unit of product low.
- The product is lightweight, making it easy to use.
To sum it up, stone wool substrate is a sustainable and environmentally-friendly product:
- Constant, controlled quality
- Clean: contains no contaminants
- Optimum control range
- High yield at high quality
- Saves on water and nutrients
- Lower energy consumption
- Easy to use
- 100% recyclable
- Sustainable and environmentally-friendly