Normally difficult to remove coatings of certain polymeric substances, including a polytetrafluoroethylene, are removed by the presently disclosed electrical stripping technique. The coatings are deposited by electrophoresis on a conductive surface of an object used as an electrode and stripped or removed from the same surface by applying a voltage of opposite polarity while the coating particles are still in an uncoalesced condition due to retention of electrolyte fluid between the particles. Certain of these coatings are strippable even after removal of the base electrode from the electrolyte medium, provided that sufficient electrolyte moisture is retained to keep the coating in a solvated condition until reimmersion and application of the reverse voltage. The deposition and stripping actions are repeatable an indefinite number of times for particular coating substances under particular conditions. This is used in a closed system to construct specific devices based on selectively variable thermal resistance effects and visual indication effects. These effects have an associated memory property in the sense that the effect persists indefinitely upon removal of the electromotive force which is depositing or stripping the coating.