| abstract |
A visual thermal history indicator comprising a pattern produced from at least two waxes wherein one wax has a melting point that differs from the other wax, or where the waxes have the same melting point but different melt flow behaviour, and wherein the pattern is adapted so that when the lower melting point wax melts or the wax with greater melt flow behaviour flows, the visual appearance of the pattern changes, and wherein when the second and subsequent higher melting waxes melt, or when the lower melt flow behaviour waxes flow, the visual appearance of the pattern changes as each wax melts or flows. |