A test sample heating apparatus and method includes a heating jacket that applies heat to a sample vessel containing a test sample. The heating jacket has a vessel-receiving recess that is sized and shaped to allow the sample vessel to be placed within the recess with limited annular spacing between at least part of the sample vessel exterior surface and at least part of the heating jacket recess interior surface. Proximate surfaces of at least one of the heating jacket and the sample vessel may be coated with a dark coating to enhance heat transfer.