forest glass

Refers to glass that was originally manufactured in the forest regions of France and Germany in the Middle Ages. It is usually greenish, yellowish, or brownish in color, and the glass is typically rather thick, simple in form, mold blown, and decorated with trailing and prunts. It is characterized by the alkali ingredient having been provided by potash from the ashes of burnt beechwod, fern (bracken), or other woods.