Spectroscopy can reveal the composition of those touch-up layers too.
光谱学也可以揭示这些修饰层的组成。
2
My lipstick needed a touch-up.
我的口红需要补一下。
《牛津词典》
3
Sometimes original art works appear questionable or inauthentic because they've had so many restorers add touch-up layers to cover up damage, damage from the paint having deteriorated over time.