Hirschkleber is used to glue vamps to toe boxes as it reinforces and hardens the toe box. It's advisable not to use on wet leather as it might cause it to darken. To use Hirschkleber for toe area, last the toe completely and allow it to dry, then pull the toe leather back, put in the toe box, and finish the toe without wetting the leather again. Hirschkleber also enables ventilation inside shoes unlike ordinary glue that seals off air vents leaving air unable to circulate through shoes.