Mineral wool is used for its ability to hold large quantities of water and at the same time maintain a high percentage of air as well. This aids root growth and nutrient uptake. The fibrous nature of mineral wool also provides a good mechanical structure to hold the plant stable. Mineral wool has a high pH, which is unsuitable to plant growth. This requires correcting or conditioning. Conditioned mineral wool has a stable pH over long periods of time.

Stone wool is the main reason that most of the worlds greenhouse vegetables are now grown hydroponically. At full saturation, Grodan holds 80-90% of its volume in water. It is wrapped in biodegradable plastic and the stonewool can be re-used in your garden to improve the aeration and water holding capacity. Grodan stonewool went into space on Challenger in 1986 and is still being used in NASA's testing with hydroponics. You will find Grodan stonewool in some garden centers and in virtually all hydroponics shops in North America.

It is back to Nature. The raw material is basalt rocks and chalk. These are melted at 1600 degrees. The lava is blown into a spinning chamber, which pulls the lava into fibers, much like 'cotton candy'. When Mother nature makes this wool we call it 'angel hair'. If you have ever visited a volcano, you may have seen the fluffy angel hair flying around.

The fibers are packed together into a mat and cut Grodan slabs & cubes from it. The stonewool granulate is bags with little flocks of 'angel hair'.

In this day and age we are all much more aware of the importance of protecting our environment. What many do not know is that growing hydroponically is far better for the environment than traditional growing methods.

You have the choice of recycling the water you drain, instead of leaching fertilizer into the ground.

Starting with a pathogen-free product, you have less disease problems and thus use far less pesticides (90% less).

Fertilizer is used only in half strength and overall a commercial grower uses only 25% of the amount of fertilizer normally required for the same crop grown in soil.

Rockwool is produced in blocks ranging in size from 1.5"x1.5"x1.5" to 6"x6"x6" and every size in between and in slabs 3 foot long x 6" wide.

Important facts about Grodan Stonewool:

* Grodan stonewool was developed in Denmark in the early 1970's. The process makes excellent use of nature resources; 37 cu.ft. of wool can be produced from 1 cu. ft. of rocks.

* Today most Grodan is pro-duced from recycled Grodan.

* Grodan stonewool is the main reason that most of the worlds greenhouse vegetables are now grown hydroponically.

* At full saturation, Grodan holds 80-90% of its volume in water. It is wrapped in biodegradable plastic and the stonewool can be re-used in your garden to improve the aeration and water holding capacity.

* Grodan stonewool went into space on Challenger in 1986 and is still being used in NASA's testing with hydroponics.

* You will also find Grodan products at the EPCOT center / Walt Disney in Florida

The fibres themselves are excellent conductors of heat, but they package air so well, that when pressed into rolls and sheets, rockwool makes for an excellent and reliable insulator. Batts, sheets and roll made of rockwool are a poor conductor of heat and sound. Fire resistive properties for mineral wools is given here in descending order:

1. fibreglass,

2. stone wool,

3. ceramic fibres.

No conventional building materials, including mineral wool are immune to the effects of fire of sufficient duration or intensity. However, each of the aforementioned three wools make common components in passive fire protection systems, such as in spray fireproofing, stud cavities in drywall assemblies required to have a fire-resistance rating, packing materials in firestops and more.

Mineral wools are unattractive to rodents but will provide a structure for bacterial growth if allowed to become wet.

Other uses are in resin bonded panels, growth medium in hydroponics, filler in compounds for gaskets, brake pads, in plastics in the automotive industry and as a filtering medium.