Mineral Magic holds more than 60% of it's own volume in water. Unlike many amendments though, that water retained is plant available and just continues to 'charge up and release' for ever. It's honeycomb like structure creates a massive specific surface area to achieve this.
Once full of water, the mineral does not change form in any way like swelling, slaking, or going soft.
The feature of the water retention is that it works totally independently of the specification of the soil and therefore does not lead inhibit the free drainage desired in winter. In fact it actually works in a positive way by drawing excess water into the honeycomb like structure and reducing the effects of waterlogging and increasing firmness.