Archaeological diggings have found intact sets of molds used in stack casting, i.e. individual molds stacked one above another and having a single gate, dating from the era AD 24-220. At the site of the kiln west of the city of Wexian in Henan province, molds were found for producing iron castings for horse-drawn vehicles, including those for bits, harness rings and buckles, and vehicle fittings. Drawings to indicate the stacking and ways to make metal masters are provided. Attempts to duplicate the use of these molds indicated the need to heat the molds to 600°C for 6 hours, then oven cooling to 300°C before pouring into the molds.