Hostapur® OSB is a powerful air entraining, wetting and plasticising agent for mineral based dry premixed plasters, renderings and trowelling compounds. Hostapur OSB forms air pores with excellent stability, reduces shrinkage particularly of cement/cement-lime based mortar systems and prevents formation of cracks. Other advantages are the higher frost resistance and reduced tendency of efflorescence in hardened mortar. Hostapur OSB leads to better wetting and dispersion of the building materials mixtures (e. g. of machine applied plasters and renderings), reduces tackiness and improves workability and pumpability of wet mortars.
The recommended concentration should be 0.005 – 0.05 % by weight, calculated on dry mortar.