a single particle of a size that is up to 4 times greater due to the fact that in one and the same starch sample there are particles with different sizes it is observed that the trivalent salts are more reactive the smaller the starch particles due to their charge distribution and their specific surface which causes a greater joining of the smaller particles of the distribution curve whereas the size of the larger particles is hardly modified since they are less reactive this phenomenon causes a modification in the particle distribution curve making the curve more restricted i e increasing the amount of larger particles and generally increasing the size increasing the starch particle size helps the starch which is in a state of suspension with water whether it is from the supply system or from the production system itself once superficially applied partly or completely on the sheet of paper already formed to remain in a larger amount increasing its performance and therefore increasing the joining between several layers of paper the physico mechanical characteristics of the sheet and reducing the amount of free starch in the process water the treatment reduces starch consumption as well as the contaminants supplied in the process and waste water by way of example a proportion of between 0 05 and 10 of al 2 so 4 3 alcl 3 or similar salts already described can be used on dry starch so that the trivalent ions after dissociation from the inorganic salt react with the starch particles pooling several of them together these salts have a higher tendency for these starch particles of a smaller size according to the type of starch these two salts.