JDs are made of ultra-low viscosity polyurethane resin that yellow with prolonged exposure to direct sunlight. The best thing is keep your dolls away from prolonged exposure to direct sunlight. When yellowing has set in, some people sand the entire surface of the doll with fine sand paper. Sanding makes the overall skin tone lighter, but it does not restore the original color. If you want some lightening, albeit subtle, sand the entire surface of the doll using only 3M’s Mirco Fine or Ultra Fine Sandpaper. If you are going to use non-3M sandpaper, use at least 600-plus grit sandpaper. You must be very careful when undertaking any aesthe (sanding) work. Without a proper understanding of the doll’s shape, excessive sanding can damage the doll’s original sculptural beauty and form.