Solvent Etching of Cellulose Acetate Specimens for Electron Microscopy

A technique is presented for etching cellulose acetate fibers and films by direct solution of the surface molecules. A relatively undisturbed interior layer of polymer is uncovered for replica tion. Etching is achieved by immersing the polymer for a short period in acetone cooled to — 50°C and then flooding with an excess of cold absolute alcohol. The resulting surfaces may be replicated for electron microscopy by any adaptable replica technique. Examples are given of the skin, orientation, voids, and pigment dispersions in cellulose acetate yarns.