3　“银镜”与黄变现象在黑白缩微胶片中 ,随着时间的推移 ,在影像的高密度部位会出现蓝黑色金属光泽的“银镜”现象 ,同时在低密度部位出现黄变现象。所谓“银镜”现象 ,是黑白银影像在长期使用与保存中 ,影像高密度处银粒子扩散迁移的一种化学变化。用反射光观察时 ,可以看到 3 “silver mirror” and yellowing phenomenon In black and white microfilm, with the passage of time, high-density parts of the image will appear blue-black metallic luster “silver mirror” phenomenon, while the low-density parts appear yellowing phenomenon. The so-called “silver mirror” phenomenon is a chemical change in the diffusion and migration of silver particles at the high density of images in the long-term use and preservation of black and white silver images. Observed with reflected light, you can see