Contriving specifications for concrete curing has been a difficult problem over the last 50 years. Improvements in curing materials have not solved this problem, indeed they have complicated it. How can we insure that concrete is cured properly? Generally, the methods in use today are indirect. That is, we specify materials which can be used for curing, we specify how to use them, and then we assume the product receives optimum curing. Perhaps a better approach might be a direct one. Allow a contractor to cure concrete in any fashion desired so long as the hardened concrete meets some requirement. In other words, examine the product directly, not the methods used and materials used to achieve it. Of course, the problem with this approach lies in "after the fact" testing. If a concrete member has been cured improperly, it is difficult to convince people that it should be removed and replaced. Ideally, a valuable curing tool might be one which could be placed in fresh concrete and which would give not only an instantaneous appraisal of curing effectiveness at a given time but would also give a warning to inspectors when improper curing is impending. Researchers at Penn State University have invented a simple device which may be able to do this. To evaluate curing, a small curing gage was conceived at Penn State. It consists of a clear plastic "button," or window member, with a relative humidity (RH) indicating chemical adherence to the underside. The chemical changes color to indicate changes in humidity. The gage can be pressed with the thumb onto the surface of fresh concrete and remain there for the life of the member. If the concrete is curing (RH is over 80 percent), the gage exhibits one color- pink, and if curing has ceased (RH is under 80 percent), the gage changes to another- blue. Tri-level indicators with indicating levels of 100 percent, 90 percent, and 80 percent RH have also been used.