Description Hydrophobic Sand
As the name suggests, hydrophobic sand is water-repellent. This means it is not suitable at all for mud pies. ;) However, it is perfect for a few experiments in water. For this, you only need a container, preferably transparent, of course water, and maybe a spoon.
Through a special treatment of the sand grains, their surface repels water. If you throw a handful of sand into a container of water, you get one or more clumps. You can shape these sand clumps underwater. Try letting the sand trickle into the water faster or slower, and you get, for example, colorful sand sausages or many small balls. :) As soon as you bring these shapes back to the air with your hand or a spoon, the sand is immediately bone dry again! So you can't bring an underwater sandcastle to land; the sand immediately becomes loose and disintegrates.
You can get a first impression of how the material behaves from the photos. But it's much more impressive to touch the sand yourself. :)
Hydrophobic sand can be used again and again. However, you should store it dry, not in water. ;) The four different colors can be mixed - but it is admittedly difficult to separate them again afterward.
So to speak, the opposite of hydrophobic sand is kinetic sand, which never dries out.