of starch of the equimolecular composition of lime and sodium carbonate identified in formulation c in addition the formulation concerned comprises two parts by weight of tspp and 400 parts by weight of the inorganic filler used for formulation a finally the amount of water sufficient to obtain a content of dry matter of the formulation equal to 75 and the amount necessary of polyacrylate of the brand 34 acrylron a 300 34 to bring the viscosity of the finished formulation to 10 000 cps are added this is a mixture comprising as starch product a composition according to the invention constituted by 79 8 by weight of potato starch modified by oxidation so that for a ratio of 10 dry matter after cooking in live steam for five minutes at 90 u00b0 c the starch gave in water a viscosity of 20 cps at 50 u00b0 c this starch mixture is present in the proportion of 18 8 by weight whilst the synthetic binder identical with that of formulation a is again present in the proportion of 80 parts by weight the previously defined starch mixture is supplemented with the same amounts as in formulation d of borax and of the equimolecular mixture of lime and sodium carbonate in addition the formulation concerned comprises 2 parts by weight of tspp and 400 parts by weight of the inorganic filler used for formulation a finally the formulation is brought to 75 of dry matter and 10 000 cps according to the same operational method.