Powdery composition comprising a) at least one powder in form of core-shell particles, the core comprising liquid water or a liquid aqueous phase and the shell comprising hydrophobized particles in form of hydrophobized silica particles, which are obtained by reacting a hydrophilic fumed silica having a BET surface area of from 270 to 330 m 2 /g with hexamethyldisilazane to give hydrophobized fumed silica particles having a BET surface area of from 200 to 290 m 2 /g and a carbon content of 2 to 4 wt.-% and methanol wettability of at least 50 and b) at least one powder comprising carrier in form of a precipitated silica having i) a BET surface area from 150 to 250 m 2 /g, ii) a particle size d 50, determined by laser diffraction, from 4 to 7 μm and iii) a DBP (dibutyl phthalate) absorption, in g DBP/ 100 g silica, from 250 to 300 and b1) at least partially water soluble liquid and/or b2) a water reactive substrate, which is not water soluble and which, when being activated by water or an aqueous phase is transformed to a reaction product or products that are water soluble, each located in and/or on the carrier, wherein the water soluble liquid and the water reactive substrate are reversibly bound to the carrier by capillary action/absorption/adsorption and can be flushed or dissolved from the carrier, in part or completely, by the liquid water or the liquid aqueous phase of the core-shell particles, the carrier itself being water soluble or not. a) at least one powder in form of core-shell particles, the core comprising liquid water or a liquid aqueous phase and the shell comprising hydrophobized particles in form of hydrophobized silica particles, which are obtained by reacting a hydrophilic fumed silica having a BET surface area of from 270 to 330 m 2 /g with hexamethyldisilazane to give hydrophobized fumed silica particles having a BET surface area of from 200 to 290 m 2 /g and a carbon content of 2 to 4 wt.-% and methanol wettability of at least 50 and b) at least one powder comprising carrier in form of a precipitated silica having i) a BET surface area from 150 to 250 m 2 /g, ii) a particle size d 50, determined by laser diffraction, from 4 to 7 μm and iii) a DBP (dibutyl phthalate) absorption, in g DBP/ 100 g silica, from 250 to 300 and b1) at least partially water soluble liquid and/or b2) a water reactive substrate, which is not water soluble and which, when being activated by water or an aqueous phase is transformed to a reaction product or products that are water soluble, each located in and/or on the carrier, wherein the water soluble liquid and the water reactive substrate are reversibly bound to the carrier by capillary action/absorption/adsorption and can be flushed or dissolved from the carrier, in part or completely, by the liquid water or the liquid aqueous phase of the core-shell particles, the carrier itself being water soluble or not. i) a BET surface area from 150 to 250 m 2 /g, ii) a particle size d 50, determined by laser diffraction, from 4 to 7 μm and iii) a DBP (dibutyl phthalate) absorption, in g DBP/ 100 g silica, from 250 to 300 and b1) at least partially water soluble liquid and/or b2) a water reactive substrate, which is not water soluble and which, when being activated by water or an aqueous phase is transformed to a reaction product or products that are water soluble, each located in and/or on the carrier, wherein the water soluble liquid and the water reactive substrate are reversibly bound to the carrier by capillary action/absorption/adsorption and can be flushed or dissolved from the carrier, in part or completely, by the liquid water or the liquid aqueous phase of the core-shell particles, the carrier itself being water soluble or not. b1) at least partially water soluble liquid and/or b2) a water reactive substrate, which is not water soluble and which, when being activated by water or an aqueous phase is transformed to a reaction product or products that are water soluble, each located in and/or on the carrier, wherein the water soluble liquid and the water reactive substrate are reversibly bound to the carrier by capillary action/absorption/adsorption and can be flushed or dissolved from the carrier, in part or completely, by the liquid water or the liquid aqueous phase of the core-shell particles, the carrier itself being water soluble or not.