An old glass manufacturing method as it used to be practiced in ancient times (for around five thousand years since mankind can make glass), namely by melting in wood-heated ovens.
Even today, there are enthusiasts loving to do exciting things just because it is a hobby. In their houses they build up a wood-heated glass oven (just as people used to for the past five thousand years since humans can make glass).
Once a year or two, such a fan must get ready a few cubic meters of wood and start heating the oven up slowly so that it does not crack. Next, he puts glass raw materials or shards into a small fireclay pan, deliberately polluted by iron in order to give the glass a slightly greenish colour tone just as the medieval products had. Such wood-heated oven can reach up to 1,320°C. The glass melt contains seeds – again reminding the ancient glassmakers’ products.
Inside the oven, above the firebox, products must be kept in a special chamber to cool down slowly and not to crack.
Also the oven itself must be cooled down slowly and conserved so that it can be used next year again. Only a few skilled glassmakers can thus make replicas of glass that can otherwise be seen only in museums.