Method for modelling the glass panes
To recreate the Middle Ages supposed shapes, the lead sections used for casting are visible in figure 1, numbers 1-5 (fig 1). When using the more realistic lead sections (fig.1, numbers 4-5), the casting leds to a curious glass pane border, with a rounded shape. Obviously, this is not the appearance of a glass cut for stained windows! Actually, the glass is cut very precisely (typically a oil filled glass cutter), but in Middle Ages a very imprecise tool was used, called grozing iron , that caused the edge of the glass to be very irregular. However, in both cases, the border of glass will not be visible in the virtual model, because it is under the lead leaf. Therefore the simplest way should be chosen, and a special set of lead sections (called “simplified lead cames” in fig. 1, numbers 2-3) be used in order to virtually cast the glass and obtain a simple edge. In case one of such glass panes would be used to zoom in the border details, a simulated grozing iron border will be created on purpose.
The putty problem
2. Corpus Vitrearum Medii Aevi glossary