According to "DollCollecting@About.com," composition dolls are made with "a mixture of wood pulp, sawdust, glue and similar items." These ingredients were mixed and then "formed using molds and allowed to harden. Composition dolls were then painted with a thick layer of flesh-colored paint. On top of the flesh paint went painted features, such as the eyebrows, eyelashes, and lips.... On top of all of the paint went a layer of sealant or varnish to protect the painted features and seal the composition." (Wisegeek.com, 'What are Composition Dolls,"Katharine Swan) In some cases only the hands and head of the doll were made of composition; while the body may have been cloth and stuffing. Over time and particularly when exposed to a varied climate (hot and cold temperature shifts or humidity) the outer layer of paint on a composition doll can develop fine surface cracks called crazing.
This composition process seems a viable explanation of the make up of my non-cloth Chinese dolls. I am still uncertain, however, as to the actual substance of the under layer. I have some question as to whether it might be plastic. This would certainly date any doll with plastics coming in to use in the doll making process in the 1950's.