• Casein: hot needle test

    Casein identification guide: casein is a thermoset semi-synthetic polymer made from milk, hardened in formaldehyde

    13. Hot needle test: slow to burn, heat aura appears around point, sizzles, smokes, smells like burned milk, usually leaves a hard ridge around test point.

    source: Button Materials A-Z: Identification Guide
    by Jocelyn Howells

    Button Specs