Otterbein NHL 3,5 is a historical, cement-free and gypsum-free, naturally hydraulic binder, which is obtained from a unique natural limestone marl and contains no other additives. It is particularly suitable for the production of high-quality plaster, grout and masonry mortar in the field of historic preservation and ecological house building. Due to its high proportion of limescale, CALCIDUR® NHL 3.5 ensures suppleness, good water retention and easy processing of the mortar ** We may change manufacturer of supplied product**