Hypertufa

Hypertufa is intended as a manufactured substitute for natural tufa, which is a slowly precipitated limestone rock; being very porous, it is favorable for plant growth.

[2] To increase structural strength and longevity, polymer fibers, liquid acrylic,[3] and fiberglass[4] may be incorporated into the mixture, along with various grades of sand, pebbles, and crushed rock which add to the final object's overall strength and stone-like appearance though they increase its weight.

Powdered concrete dyes (in small amounts) also tint the hypertufa to resemble natural rock.

[3] After water is added to the mixture, it is packed into a previously constructed mold, then sealed or covered in plastic and allowed to cure.

After the hypertufa object is completely cured, it is removed from the plastic, rinsed thoroughly, and allowed to sit exposed to the elements for several more weeks to reduce its otherwise-toxic surface alkalinity.