Actes du premier colloque international de l'association Verre et Histoire, Paris-La Défense / Versailles, 13-15 octobre 2005

Prof. J. CAEN, Hogeschool Antwerpen (AUHA), Conservation Studies, Antwerp (Belgium)
Prof. Dr. B. DE MUNCK, University of Antwerp (AUHA), History Department, Antwerp (Belgium)
Dra. V. DE LAET, University of Antwerp (AUHA), History Department, Antwerp (Belgium)

Technical Prescriptions and Regulations for Craftsmen in the Southern Netherlands during the Sixteenth, Seventeenth and Eighteenth Centuries.
A Confrontation of Archival and Material-Technical Information regarding Glazing and Stained-Glass Windows.

Quality of the lead, leading up and soldering

In the Antwerp ordinance of 147040, we find the earliest recorded guideline pertaining to the quality of the lead strips and cames. The lead strips had to be long and strong enough so that they could be wound twice around the glazing bars, as was customary. The cames had to be symmetrically planed, so that the two openings of the H-profile were equally sized. Faulty lead cames could, however, be used on the outsides of the panel insofar as the edges of the glass pieces were not visible and on condition that solder was applied plentifully (‘sondueren van goeder vetter stiffen maken’). We also learn from the document that the lead was produced by casting a lead rod and then planing out the grooves in the cames. This rather cumbersome procedure became obsolete by pressure of the introduction of the leadmills. Despite the resistance of the corporations, the usage of the leadmills became a common practice by the end of the ‘Ancien Régime’, most probably by the end of the 17th century. However, the question does arise whether the quality of the cames produced by means of a lead mill was anywhere as good. After all, cold rolling of lead modifies the internal structure of the metal, so that it becomes more brittle.

In the Netherlands, we sporadically encounter lead cames with grooves that have been cut out. In the previously mentioned guild chapel windows in Bruges41, small remnants of the original lead were found in various places (including around the eyes of the monsters) (see fig. 7-8). It is noticeable how strong and good-quality these lead cames are. At the same time, they are quite thin. This suggests that the lead was probably not only of a better quality, but also artistically more elegant than the subsequent releading of many of the windows.

The same ordinance also imposes strict requirements in relation to the leading and soldering of windows. Before leading, the cut side of the glass pieces needed to be meticulously nibbled down, until the edges were clean and straight. Then, the pieces had to be placed carefully into the cames and everything had to be pushed together, so that the panels fitted tightly in the middle as well as around the borders. Loose glass was, after all, a cause of many complaints. Subsequently, it was important that the lead cames (for panels intended for private homes) should be straight, so that all soldering points were nicely aligned. The soldering was supposed to ensure that the glass was tightly set, both in the middle and on the sides.

The quality of the lead was a regular cause of concern to the guilds. This is especially apparent from 17th and 18th century texts from Antwerp, in which it is repeated on several occasions that fines or confiscation could be imposed for using lead that was too light or for lead having holes in it, or that had been rolled with a lead mill.
It appears from a copy from 167742 that, as early as 1612, the aldermen of Antwerp conducted an investigation into the quality of the work performed by the city’s glaziers after numerous complaints about windows that had not been properly leaded and promptly began to sag and bulge.
The ordinance from 161343 was issued after fresh complaints from customers about the use of inferior lead cames that were, moreover, of the wrong thickness. Also, the lead strips appeared often to be too short and of the wrong thickness. The text emphasises that the cames should be of the right thickness and that their length should be proportional to a certain weight. The use of a lead mill to roll lead cames was strictly forbidden. After two infringements, the offender would not be fined, but his lead mill would be confiscated.
In order to enforce this regulation, the so-called elders of the guild would pay regular visits to workshops under suspicion.

In 174344 and 174445, the ordinances of 1613 and 1677 were again reiterated in their entirety. In the 1743 text, the stipulation is added that inferior work may be removed and replaced with proper panels at the expense of the glazier.

It is quite striking how the same regulation is repeated so frequently and with such emphasis over such a long period of time. This may well be an indication that numerous infringements occurred, for example by craftsmen in the countryside or by individuals who were working in the city illicitly and were not even members of the guild. The reason most probably lies in the material culture of the time and the changing tastes of customers. Certain fashions caught on among members of the middle and even the lower classes, who had less money to spend and were therefore offered lower quality panels. And this is precisely where the guilds ran into trouble: their strategies only made sense in a market of expensive and durable products. It would appear, then, that the so-called consumption revolution spelt the end of the guild system.

∧  Back to topMastic Cement / Sealing

The previously mentioned Antwerp ordinances of 1470 and 1472-1488 stipulate that the lead composition should be properly sealed with mastic, so that the glass would not rattle (‘alsoe reynlic vueghen sal als dat dloodt oft gelas nerghens loutere’)46. The main purpose of applying mastic cement is to keep the glass pieces fixed in the lead composition, but it speaks for itself that this also makes the panels stronger, as well as water- and windtight.

∧  Back to topFitting in the window frame

As far as the placement of panels in window frames was concerned, the guilds would appear to have been preoccupied primarily with the strength of the construction. According to an Antwerp ordinance dating from 147047, if panels were placed in a freestone frame, the iron rods (‘gheerden’) on either side of the panel had to be anchored sufficiently deep into the stone. The required depth equalled the breadth of the lead came. In this manner, one could prevent that either the panel or the rod would come loose.

However, in the case of softer stone, the required depth of the rods in the stone was three lead breadths.

If the glazier noticed when taking measurements that the iron rods were not firmly fixed in the stone, he was required to remedy this before proceeding with placing the panels.

∧  Back to topConclusion

Thanks to the quality of their products, crafts guilds were able to compete successfully for several centuries. They responded to the production of and trade in cheap and inferior items (often produced in rural areas) by issuing strict regulations regarding the materials to be used, the methods to be applied, the required quality of finishing and the training of producers.

As for the glaziers’ and the stained-glass guilds in the Southern Netherlands, we propose that they were not so much concerned with safeguarding their trade against new labour-threatening technologies as with guaranteeing the quality and durability of their products and with protecting the consumer. Their strategies seem to have been relevant in the economic and cultural context they worked in.

The question whether and why this eventually changed, is difficult to answer with the information we have for the moment. In the 17th and 18th centuries, these guilds were confronted with new problems. The rise, towards the end of the 17th century, of casement windows with wooden glazing bars (‘chassisraemen’)48 resulted in a sharp decline in demand for leaded glass. In this context, one would expect demand for craftsmen possessing leaded-glass skills to decline as well. Competition from the countryside was fierce, as many town dwellers also had their glass cut more cheaply by rural craftsmen. So perhaps the specific organisational form of the glaziers’ and stained-glass crafts, which was geared entirely towards collective agreements, was unable to face up to this new challenge.

More research is needed to shed more light on these questions, but it is clear that the shift to cheaper and fashion-sensitive products was all but favourable for the guilds’ privileges.

∧  Back to topAcknowledgements

The authors wish to thank the Hogeschool Antwerpen and the University of Antwerp, both partners in AUHA, for funding this research project.

  • 40.  CAA, Ordinance of 1470, Book of Privileges of the Saint-Luke Guild (1442-1672), f° 4r° and f° 4v°.  ↑
  • 41.  Bruggemuseum, inv. n° 0.81.XXII a-b.  ↑
  • 42.  CAA, Quality survey of 10 January 1677 (copy from the original of 16 July 1612).  ↑
  • 43.  CAA, Ordinance of 1 April 1613, Book of Privileges of the Saint-Luke Guild (1442-1672), f° 34 r° - f° 36 v°.  ↑
  • 44.  CAA, Request of the glaziers guild, 1743, f° 1r° and f° 1v°.  ↑
  • 45.  CAA, Ordinance of 15 June 1744.  ↑
  • 46.  CAA, Ordinance of 1470 and 1472-1488, Book of Privileges of the Saint-Luke Guild (1442-1672), f° 4r° and f° 4v°, f° 7r° and f° 7v°.  ↑
  • 47.  CAA, Ordinance of 1470, Book of Privileges of the Saint-Luke Guild (1442-1672), f° 4r° and f° 4v°.  ↑
  • 48.  CAA, Request of the glaziers guild, 15 January 1691, f° 1v°.  ↑