6.8 Visual appearance. The simplest way to evaluate a conversion coating is to observe color, continuity in appearance, smoothness and adhesion to the base metal (see 3.5). Visual examination is performed to ensure that proper cleaning and coating procedures were used such that a coating with sufficient protection exists over the entire part. Materials qualified under MIL-DTL-81706 produce coatings that range in color from clear/colorless to iridescent yellow, brown, gray, or blue. It may be possible to develop acceptable color levels for a particular coating system by use of color chips. The following circumstances may exist that relate to color uniformity: