Dating stained glass is not a simple task. The techniques, colours, designs, window tracery, ferramenta, content, symbolism, intended purpose, commission and position need to be examined. This post is to give an introduction to some of the considerations.

Between the 12th and early-16th centuries a vast amount of stained glass was produced for churches. The bright, jewel-like colours produced images relating to Christian doctrine for both the clergy and laity to ‘read’ and make their own spiritual connection. In our modern society we are so used to reading words. In the medieval world, where only the privileged few were literate as we understand it, the majority were educated in the literacy of images. The figures, colours, designs, scenes, symbols, and spiritual truths contained within stained glass were meaningful in a way that is remote to current society.

The church of the medieval world was full of colour and reflecting light. Along with the colours of the stained glass, illuminated with external natural light, there was gilding and candlelight, wall paintings, painted wood, coloured statues and cloths. There could be decorative marble, such as polished limestone or decorated tiles. This was a time when the belief in the divine could be experienced through the senses. The images could be instruction for laity, devotional or part of the liturgy.

For historians the position of a stained-glass window in a church can provide information on the individual or group that commissioned them. For example, in the nave a private window donated by a family or guild and its position nearest the east end could point towards a position in wealth and status. This is particularly relevant from the 14th C when wealthy merchants, donors and guilds started embellishing their local churches. Earlier the private individuals may well have been an aristocratic family embellishing their family chapel.

Coloured Glass – Anglo-Saxons of the late-7th century onwards

The Venerable Bede (d. 735) writes in his Historia ecclesiastica gentis Anglorum (An Ecclesiastical History of the English People) of Bishop Benedict Biscop (c. 628-690). Benedict Biscop brought stonemasons and glaziers from France.[i] In the Anglo-Saxon church of St Paul’s in Jarrow (originally part of the monastery) is one of the earliest examples of stained glass in Western Europe. It is an example of different coloured glass, held together by lead, without any image.

The Making of Stained Glass – A 12th-C treatise

Theophilius Presbyter (d. circa 1125), a German or Belgian monk, wrote a Latin text describing the methods associated with medieval arts. Schedula diversarum atrium (“List of various arts”) or De diversis artibus (“On various arts”). This informs us of the following:[ii]

  • An initial sketch design was produced by either the master glazier or an illuminator of manuscripts.
  • The glass painter made a full-size working drawing of the window, with a heavy black or red line, on a whitened tabletop. The image would contain all the details including the position of the lead armature.
  • Different colours were indicated by letters.
  • The appropriate coloured sheet of glass was placed over the drawing and the individual shaped piece was cut by using a red-hot iron – after starting a crack by dropping water (or probably spitting) on it.
  • The shaped piece was refined by snipping round the edges with a notched grosing (or grozing) iron.
  • With the cut shapes laid out on the drawing, the glass painter could trace the images onto the surface of the glass.
  • The enamel paint was made from copper or iron oxide, mixed with a flux of finely pulverised soft glass and a ground medium of gum and water, urine or wine.
  • With the painting complete the pieces of glass were placed on an iron plate that had been previously covered with a fine layer of ash or quicklime and fired in a kiln.
  • A firing would have been required for each layer of fresh paint.
  • One the firing was complete then the glass would be joined with the thin strips of lead (made in an ‘H’ section to accommodate glass sliding in each side).
  • The joints were smeared with suet or resin and then each side soldered.
  • The joints between the glass and the lead needed to as watertight as possible.
  • Then strips of lead were soldered on at various points to secure the panel to the fixing bars.

Creating the Colours & Artwork of Stained Glass

The base material of stained glass is the glass itself. Coloured stains were applied to give sheets of glass colour. In the medieval period the base sheets of coloured glass were often bought from the continent. Image detail was painted onto the glass and fired to fix the colours (at 650 degrees in a furnace). Iron or copper oxide mixed with ground glass, with the addition of red wine or urine formed the basis of paints. Cobalt could be added for blue or gold for a pink or ruby colour. From the 14th C silver nitrate would be found to produce a range of yellow or orange colours. The term ‘stained glass’ is a general term. It fails to distinguish the artistic skill of the artist painting on the glass.

Grisaille is lead-white or clear glass. This does brown or green with corrosion over time.

Elements that contain and protect the glass in a window

Firstly, there is the tracery, which can help date the window. Then there are the elements that hold the glass in place:[iii]

FERRAMENTA – The range of ironwork set into the masonry of a window to provide support for the glass panels

Armature – is ‘a shaped iron framework inserted into a lancet window-opening to provide support for panels of stained glass. Armatures were common until the late thirteenth-century.’[iv]

Stanchion – vertical bar set into the window masonry. May pass through a lug in a saddle bar

Lug-Bar– ‘flag, slotted support bar to which stained glass panels are attached using a wedge of metal.’[v]

T-Bar – ‘…set horizontally into the masonry of a window opening at the divisions of the stained-glass panels. Each bar supports and spreads the vertical weight of the panels resting on them’ [vi]

Saddle Bar (or Tie Bar) – horizontal-set bar set ‘into the masonry of the window to which the stained-glass panels are tied with lead or copper ties, supporting and preventing panels from flexing out of the vertical plane’.[vii]


Calmes or Cames – cast strips of lead, H-shaped in section. These held the pieces of glass gother.

The centre of the lead is called the heart – the area that covers the glass is called the flage or leaf.

Solder– the leads are soldered at the points of intersection.

The beginning of images in stained glass – Gothic of the 12th C

Abbot Sugar, a significant early patron of Gothic architecture, was Abbot of St Denis, which he set about rebuilding from circa 1137. This new architectural innovation allowed larger windows with pointed arches. He was a pioneer in installing stained glass windows in his church and stated that:

 The pictures in the windows are there for the purpose of showing simple people who cannot read the Holy Scriptures, what they must believe.[ix]

The Gothic canopies in the images are reminiscent of shrines. The images in the tracery lights remind of the heavenly kingdom. This is where one might see angels, those in heaven or a heavenly city.

Developing the stories in glass – 13th C

The themes that developed in stained glass were scenes from the Old and New Testaments, the genealogy of Christ (Jesse windows), saints, prophets, Christ on the cross, etc. The Bible (Vulgate at the time) was the necessary resource. This along with a popular book compiled in the mid 13th C – the Legenda Aurea (Golden Legend) by a Genoese archbishop, Jacobus de Varagine (d. 1298) – provided the hagiographies of the saints.[x]

Figure 2: Canterbury Cathedral has some of the finest stained glass in England dating from the early 13th C. The scene is the Visit of the Queen of Sheba to Solomon. Notice the camels! © Jules & Jenny from Lincoln[xi]

Figure 3: Late-12th /early-13th C stained-glass – Dean’s Eye Window, on the north side of Lincoln Cathedral. One of the two rose windows at Lincoln cathedral (the other being the Bishop’s Eye circa 1330). In 1185 there was an earthquake that mostly destroyed the cathedral. St Hugh of Lincoln commenced rebuilding the cathedral in 1192, which was completed in 1235. This window dates from this rebuild.[xii]

14th C Innovation

It was found that applying a solution of sliver salt to the surface of the glass and firing it, the glass became stained yellow. The amount could be varied along with the firing temperature to produce different colours – from light yellow to deep red-orange colour.[xiii]

Figure 4: This stained glass is in the chapel of the Trinity Almshouses in Salisbury. They were founded in 1379 by Agnes Bottenham and rebuilt in 1702.[xiv] This glass survives from the 14th C.

Figure 5: Notice the pitting on the glass – small cavities or craters in the surface of the glass. This is caused by corrosion usually from exposure to moisture.[xv]

Glaziers Workshops & Guild

The glaziers established workshops and some of these are named – for example in, York, Exeter, Kings Lynn, Norwich, etc. The most accomplished and expensive artists were called around the country. There are some instances of them travelling to the continent. Although it was made law that only apprentices could be English.

The origin of the Worshipful Company of Glaziers and Painters is not known. However, the earliest record is that dated December 1328 (Edward III’s reign commenced 1327). They have their own arms, which was described by the Herald Robert Cook, Clarencieux King of Arms on his official visited in 1588. The arms include grozing irons, nails and a torch. Their motto is Lucem Tuam Da Nobis Deus (“O God, give us Thy Light”).[xvi]

Their hall (first known record 1601) was destroyed in the Great Fire of London in 1666 and their meetings were subsequently in the halls of other Companies or taverns until 1977.[xvii] Today their hall, Glazier’s Hall, a former 19th C dockside warehouse, is located at the south end of London Bridge (the only Livery Hall situated south of the Thames).[xviii]


The evolution of stained glass involves developments in glass colour, lead work and artistic techniques. The subject matter of the glass develops from the early-medieval period. From plain-coloured glass in the Anglo-Saxon period to painted religious subjects such as: saints & martyrs, The Holy Trinity, the Jesse Tree, visions of Heaven and Hell, religious instruction & liturgy and images relating to morality. As the medieval period develops so does the desire for individuals making their mark. This may be the coat of arms of a noble family in a chantry chapel, a memorial window or images of donor individuals, families or groups.



[i] ‘History of St Paul’s Monastery, Jarrow’, English Heritage, <> [accessed 28 March 2021].

[ii] English Stained Glass

[iii] ‘Illustrated Glossary’, The York Glaziers Trust, [accessed 22 March 2021].

[iv] ‘Illustrated Glossary’, The York Glaziers Trust, [accessed 22 March 2021].

[v] ‘Illustrated Glossary’, The York Glaziers Trust, [accessed 22 March 2021].

[vi] ‘Illustrated Glossary’, The York Glaziers Trust, [accessed 22 March 2021].

[vii] ‘Illustrated Glossary’, The York Glaziers Trust, [accessed 22 March 2021].

[viii] ‘Illustrated Glossary’, The York Glaziers Trust, [accessed 22 March 2021].

[ix] John Baker, English Stained Glass (London: Thames and Hudson, 1979), p. i.

[x] Baker, p. ii.

[xi] Jules & Jenny, ‘Solomon The Queen of Sheba’,  Wikimedia Commons,,_window_nXV_detail_(46220636645).jpg#/media/File:Canterbury_Cathedral,_window_nXV_detail_(46220636645).jpg[accessed 17 April 2021]

[xii] ‘Lincoln Cathedral’, Wikipedia [accessed 18 April 2021].

[xiii] Baker, p. ii.

[xiv] ‘Trinity Almshouses Trinity Hospital’, Historic England List Entry 1243305 (28-Feb-52) [accessed 22 March 2021].

[xv] ‘Illustrated Glossary’, The York Glaziers Trust, [accessed 22 March 2021].

[xvi] History of The Company’, The Worshipful Company of Glaziers & Painters of Glass, [accessed 28 March 2021].

[xvii] ‘History of The Company’, The Worshipful Company of Glaziers & Painters of Glass, [accessed 28 March 2021].

[xviii] ‘Glaziers’ Hall’, The Worshipful Company of Glaziers & Painters of Glass, [accessed 28 March 2021].


Baker, John, English Stained Glass (London: Thames and Hudson, 1979)

‘Glaziers’ Hall’, The Worshipful Company of Glaziers & Painters of Glass, [accessed 28 March 2021]

‘History of St Paul’s Monastery, Jarrow’, English Heritage, <> [accessed 28 March 2021]

‘History of The Company’, The Worshipful Company of Glaziers & Painters of Glass, [accessed 28 March 2021]

‘Illustrated Glossary’, The York Glaziers Trust,[accessed 22 March 2021]

‘Lincoln Cathedral’, Wikipedia [accessed 18 April 2021]

Trinity Almshouses Trinity Hospital’, Historic England List Entry 1243305 (28-Feb-52) [accessed 22 March 2021]