An editorial comment on two articles in the American Library Journal (1986-1987). K. Nyren had asked why the Library of Congress was persisting with the diethyl zinc mass deacidification method. In his reply, W.J. Welsh defended the need to stop new materials from deteriorating, by deacidifying as they enter the collection; the materials already in the collection will be, and are already being, treated. A plea is made for support above all from librarians, for the Library of Congress: whichever deacidification system is used in the future, all effective methods - and the diethyl zinc method has been shown to be so - should be used now.