readily and quickly wet dispersed or dissolved by the liquid component of the impression material to provide a composition wherein dusting is significantly reduced and the powdered components are significantly more rapidly wet upon mixing as compared to the same composition absent the coating agent the preferred composition of the invention has a dust index of less than about 100 using a gelman air analyzer see example 4 the invention will be more fully understood in conjunction with the following examples thereof which examples merely are illustrative and should not be considered to be limitive of the materials and procedures employed in practicing the invention ______________________________________component parts by weight______________________________________sodium alginate 14 0calcium sulfate 17 4tetrasodium pyrophosphate 2 5potassium titanium fluoride 1 0magnesium oxide 2 6diatomaceous earth filler 57 8polypropylene glycol coating agent 4 7______________________________________ the diatomaceous earth filler was wet with the polypropylene glycol coating agent before being admixed with the other powdered components the entire mixture was blended in a ribbon blender a 14 gram sample of the resulting mixture was placed in a mixing bowl mounted on an 34 alginator 34 produced by cadco products an appropriate quantity of water was then added to the bowl and the 34 alginator 34 was caused to turn a spatula was held in a fixed position in the turning mixture and it was observed that after 5 seconds the alginate powder was wet it was also observed that there were no dust particles released upon stirring the procedures of example 1 were repeated except that potassium alginate.