this invention relates to a reaction product of allantoin and formaldehyde made in a molar ratio of about 1 : 2 . 75 - 1 : 3 . 25 , preferably 1 : 3 , respectively , preferably under controlled ph and temperature conditions , which product contains free formaldehyde , and methylene diol of about 580 - 1385 ppm , preferably at a ph of 7 . 2 , with advantageous long - lasting , anti - microbial properties , particularly against the organism b . cepacia , and in combination products with parabens and iodopropynyl butyl carbamate .