In 1990, at a prominent U.S. Dental products manufacturing company known as CDI, a unique new liquid was developed with the specific purpose of removing impurities from plastic and metal surfaces. As part of a technical surface preparation process, the aim of the product was to cleanse the surfaces of rigid molds prior to the pouring of refractory high-heat silicates. Upon release of this product, the director of CDI, also being a highly regarded numismatist, found that not only did this liquid remove surface dirt, impurities, gums, grease, varnish, inks, etc., but it also quickly removed surface PVC (polyvinyl chloride aka “green-residue”) from coins as well. Not only did the liquid rinse away the PVC, but it did not disturb the metal in any way. Surface “toning” was left completely intact while contaminants were rinsed off with ease. After repeated tests on different metals and on many surface problem coins, especially those with slime, darkened ash, dirt and wet or dry PVC, the liquid removed residues consistently while leaving the original coin surfaces undisturbed. A collector’s dream remedy. "Because Sometimes We Need It."