Forest glass
Glass Dictionary

Glass made in the rural glasshouses of central and northern Europe in the late Middle Ages and the early modern period. Most forest glass was fluxed with potash derived from the wood with which the furnaces were fueled. It is green because of iron impurities in the sand from which it was made. The German term for forest glass is Waldglas.
Alternate Spellings:
waldglases
waldglass
waldglasses
Term Variations:
Waldglas
Artwork Examples: