A good answer depends on the volume of clippings you are working with and how much you can spend on each. I will pass on the effect of chemical treatments on newsprint that is already aged, that is a little over my head. But based on what knowledge I do have, placing the clipping between two sheets of Mylar that are then 90% sealed with tape or heat/pressure is a easy, but expensive, way to deal with a limited number of clippings.