What are the spots on the plastic surface of the slide?

Small spots on the plastic surface of the slide are pigment residues from the previous production run that were still present in the injection molding machine's pipes from the earlier production series. Despite intensive and careful cleaning of the molds and flushing of the pipes, this occurs and is unfortunately unavoidable when switching colors. It is particularly noticeable on slides with lighter colors. This discoloration goes entirely through the material and unfortunately cannot be removed. With use, the surface of the slide will eventually also get scratches and dirt, making this imperfection less noticeable to you.