Storage For extended periods of time, the lenses should be stored in a "dry box" environment. This entails the use of a desiccant (e.g., silica gel) or a heat source to prevent humidity from leaching the lens material. This is much more critical for non-coated lenses, since AR coatings help to protect the lens surfaces from humidity. For short term storage (less than a month), the plastic box and foam packing in which the lenses are shipped will provide adequate storage. In addition to humidity requirement, the lenses need to have sufficient spacing to avoid potential damage such as chipping and scratching from other lenses. For this reason, NSG storage boxes have built-in slots in which the lenses are placed, with surrounding packaging to hold them securely in place. Handling After opening the lens boxes, it is important to exercise extra care in lifting the plastic shield. Particularly with smaller lenses, it is possible that they may cling to the shield and be lost during removal. Lenses should be handled with stainless steel tweezers, preferably those with a tapered end. Lenses should be picked up out of their individual compartments by firmly holding each by its side surface (not the ends). Cleaning At times it is necessary to clean the lens surfaces due to the presence of some dust or film which may impair the image. NSG generally recommends the use of methyl alcohol as a cleaning solvent. Acetone may also be used, without harm to the lens, but it should be pure enough to no leave a residue on the lens' surface.