reference e maruszewska wieczorkowska j michalski roczniki chemii ann soc chim polonorum 37 1315 1963 the polyamides used in the process of this invention are conventional they embrace aliphatic polyamides and likely 34 mixed 34 polyamides prepared from aliphatic diamines and aromatic diacids preferred polyamides are nylons including but not limited to nylon 6 and nylon 6 6 these and other nylons known in the field are well described as to structure and manufacture and for further reference attention is invited to the patent and general literature for example the kirk othmer encyclopedia of chemical technology 3rd edition john wiley and sons under the headings 34 polyamides 34 34 polyamide fibers 34 and 34 polyamide plastics 34 as well as the encyclopedia of textiles fibers and non woven fabrics john wiley and sons inc 1984 pages 347 380 relating to polyamide fibers for the purposes of the present invention nylon 6 6 is the most preferred species commercial polyamides especially nylons used in fiber manufacture are often produced in the presence of titanium dioxide tio 2 which is added to improve visual properties of the product for example as a delusterant titanium dioxide is added in particulate form and contains up to about 8 by weight of alumina to modify tio 2 acidity and improve its dispersibility the titanium dioxide and alumina may be admixed by any conventional mixing method although methods which concentrate the alumina on the titanium dioxide particle surfaces are preferred other additives may also be present in the coating composition but such additives are believed to be substantially inert in the polyamidation reaction the presence of alumina however has a seriously deleterious effect on the catalytic activity of conventional phosphorus containing amidation catalysts and it is a surprising and unexpected result of the present invention.