Can anyone with a DC whose school uniform contains a clip on tie please tell me: what material is the clip made of, and does any part of it come in contact with the skin when worn?
School uniform shop says 100% polyester but I'm guessing that's the tie not the clip?
DD wore a clip-on at her previous school. The clip was metal but I can't remember seeing anything about what. There may be a way of not clipping them over both layers of shirt material at the neck, but normally the metal does potentially touch the skin.
If you are worried about contact dermatitis or an allergic reaction (DD had no problems and never mentioned any of her friends having any, though), I would ask the shop for details of the manufacturer and contact them direct.