SCIENCE GIZMOS: Giant Expanding Spheres | Excellent scientific demonstration

Science Gizmos.

Grow gigantic gel like spheres in hours. A 15 mm dia. soft sphere will expand to 77 mm in 120 hours.
27 spheres supplied. Super absorbent polymers absorb large volumes of water when placed in water and are turned into hydro gels.
The volume change can be an incredible 250x of the original volume and is fully reversible.
The gelled polymer contains up to 98% water so it has the same optical density as water and becomes invisible in water.
Can be coloured by added food dye.

Smaller clear spheres (PBSM46C) are available.
Note that these clear spheres can easily be coloured using food colouring.