Introduction 49
becomes darker, the iron light grey, while the phosphorus remains bright. The
patterns visible on the blade also marked its quality.197
Three main types of pattern welding can be distinguished: 1. full damast
(‘Volldamast’): the central part of the blade was forged from a pattern welded
stick (in most of the cases fishbone pattern) and the edges were welded to this
central part. 2. layer damast (‘Schichtendamast’): the core of the blade is com-
posed of flat steel covered by two pattern welded layers on each side, while the
edges were made of high-carbon steel welded on the sides. 3. covering damast
is in fact a special kind of layer damast: the blade was made of a homogenous
steel covered by pattern welded layers.198 During the Early Middle Ages the
most common pattern created by pattern welding was a fishbone-pattern. The
bending of pattern welded layers is a more difficult process, formed by multi-
plying layers and increasing quality.
The properties of the blade could be modified by various surface treatments.
The surface of the forged product is usually uneven, therefore it was whetted or
planished by hammering. Unfortunately in most of cases the original surface
of artefacts from archaeological contexts is not observable.
The hardness and elasticity of the blade could be controlled by various heat
treatments: in the case of a too hard and brittle blade it could be softened by
re-heating and slow air cooling called annealing.199 If the goal was the harden-
ing of the blade carburisation or cementation was applied: during this process
the steel was forged over charcoal, due to this procedure the iron in the state
of yellow heat absorbs carbon monoxide (CO) creating a layer of cementite or
iron-carbide (Fe3C) on its surface. The catalyzer was usually a material con-
taining nitrite (like charred leather or horn). The carburisation was used only
on some parts of the blade (primarily on the edges), while other parts were
covered with clay for preventing the infiltration of carbon, hence these parts
could stay soft and elastic.200
A different and more drastic method for hardening the blade was water cool-
ing known also as quench hardening. This process was mainly used for high
carbon steel, the hardness of which could be doubled or tripled by the quick
water cooling, resulting in a modified crystal structure to the iron composed of
197 The so-called Damascus or damast steel was made by a different process, thus the com-
posite steel of the Early Middle Ages is called pattern welding, while the manufacture of
Damascus steel damascening. (Maryon 1960, 29).
198 The types of pattern welding were described by Wilfried Menghin (1983, 17–18), but for
the most detailed description, see: Maryon 1960.
199 Pleiner 2004, 199.
200 Pleiner 2006, 66–67.