Internal and external dyes
Internal and external dyes refer to the different types of colorants used in various industries. Internal dyes are substances that are added to materials during their production or processing to impart color from within, such as pigments in paint or colorants in plastics. External dyes, on the other hand, are colorants applied to the surface of materials, like fabric dyes or ink for printing, to create a visually appealing and lasting color effect.