The invention relates to a kit of parts comprising a Base Paste (B) and a Catalyst Paste (C), Base Paste (B) comprising a cationically hardenable component, Catalyst Paste (C) comprising a starter component suitable to contribute to the hardening of the cationically hardenable compound, the composition obtained when combining the compositions of Base Paste (B) and Catalyst Paste (C) comprising in addition a porous water-adsorbing component and water, the porous water-adsorbing component being selected from molecular sieves, zeolites, silica gel and mixtures thereof, wherein either the porous water-adsorbing component is present in Base Paste (B) and the water is present in Catalyst Paste (C), or the water-adsorbing component is present in Catalyst Paste (C) and the water is present in Base Paste (B). The invention also relates to a dental retraction composition obtainable by mixing Base Paste (B) and Catalyst Paste (C) and to a process of taking a dental impression and/or conducting a dental retraction using the kit of parts.