situ by means of vaporization of ammonia from the aqueous solution and subsequent fluff or flash drying causing the polymer to coat the fibrous substrate preferably the polyacrylic acid solution is first partially neutralized by the addition of a strong alkali such as sodium hydroxide the extent of neutralization is preferably between 20 and 80 of the available carboxy groups the extent of the partial neutralization will influence the rate of water absorption of the final superabsorbent product the solution ph is then adjusted to between 7 and 9 and preferably to between 7 5 and 8 with an ammonium compound either ammonium carbonate ammonium hydroxide or a combination thereof between 0 5 and 10 by weight of polyvalent metal salt is added thereto preferred metal salts include aluminum acetate and ammonium zirconium carbonate to the above polymeric solution are added synthetic fibers from 1 8 to 3 4 inch long having a denier of 0 9 to 3 the synthetic fibers can be but are not limited to polyester polyolefin polyacrylonitrile polyamide nylon dacron rayon or cellulose acetate once the fibers have been slurried in the aqueous solution they are fluff dried by suspending the fibers in a stream of hot air generally from 60 u00b0 to 100 u00b0 c however heat is not necessary to the fluff drying which can take place at room temperature the purpose of drying by fluff drying is to draw off the moisture in order to make certain that the dry fibers will be discrete and not matted the dry fibers are then collected on a screen for use in converted products superabsorbent.