National Gallery, London: a Venetian pastiglia frame
Giovanni Bellini’s St Jerome in the National Gallery, London, has recently been reframed in a beautifully-preserved and very appropriate late 15th-early 16th century Venetian pastiglia frame.
Giovanni Bellini (fl. c. 1459-d.1516), St Jerome reading in a landscape, c.1480-85. National Gallery, NG281
Frames of this type are perhaps the earliest to use pressed and applied decoration, rather than ornament carved in the wood . They take a very simple form – two well-defined shaped mouldings, between which lies a slightly cambered or cushion frieze, covered with a layer of pastiglia, or thick paste, impressed with a running pattern. Pastiglia is the Renaissance equivalent of compo or composition, the moulding material which became popular in late 18th century Britain, or of plaster, its French equivalent. It was made in a similar way to the latter (see below), and mixed to a dough, which would be pressed into oiled moulds whilst warm, allowed to cool, and taken out and left to dry before being applied to the wooden surface. Considering that frames decorated with moulded pastiglia can be 500 or more years old, those which remain to us have lasted extraordinarily well, especially in comparison with compo frames.
Cassetta frame with pastiglia relief, 1500-50 (c) Victoria and Albert Museum, London
Although not exactly common, there are more surviving pastiglia frames than might be imagined; many museums seem to have one or more. Their decoration falls mainly into three types: the double guilloche of the Bellini frame, an all-over pattern of imbricated scales or feathers, and a more varied grotesque ornament, which is different on the vertical and horizontal rails of the frame (above). There may, of course, have been others. Their charm lies partly in the refinement and delicate execution of the ornament, partly in the proportions of the frieze and mouldings, and partly in the relatively small size of these frames.
Giovanni Bellini, St Jerome reading…, National Gallery, NG281; previous frame
The previous frame for Bellini’s exquisitely luminous St Jerome was a rather unconvincing reproduction cassetta, with an anachronistic canted frieze and the sort of decoration which looks like expensive gift wrap. The new pastiglia frame was acquired in Italy, from a family business in Modena. It was almost exactly the right size for the painting, only having to be reduced slightly in width, and the finish restored to something truer to gilding aged by more than 500 years. Some of these frames (notably two in the Metropolitan Museum, New York, and one in the V & A, London) show evidence of paint as well as gilding; this may have been the case generally for the type, so they would originally have presented a much richer and more colourful appearance – rather like silk braid or brocade.
Workshop of Domenico Ghirlandaio (1449-94), Portrait of a girl, c. 1490. National Gallery, NG1230
The National Gallery has other Renaissance paintings framed in the same style; one is this portrait from the workshop of Ghirlandaio, acquired in 1887 and framed between 1931 and 1971.
Raphael, The Madonna of the pinks (‘La Madonna dei Garofani’), c. 1506-07. National Gallery, NG6596
Raphael’s Madonna of the Pinks (for which see ‘National Gallery frames: an interview with Peter Schade’) is another; and the third is a Lamentation by Dosso Dossi.
Dosso Dossi (fl. 1512- d.1542), Lamentation over the body of Christ c. 1510-20. National Gallery, NG4032
This frame, with its imbricated scale or feather pattern and unusual narrow leaves across the corners, was acquired from the sale in 1995 of the framemaker, Paul Levi . Sadly, it has lost its original sight moulding, as can be seen by comparison with the previous examples, and also much of its gilding. The fine detail of the pastiglia moulding can still be appreciated, however: the minute fan-like veining on each feather – for these must be feathers, each with its central ‘eye’, like a peacock’s tail.
Dosso Dossi, Lamentation…, detail
The separate strips of pastiglia which make up the running pattern can be seen by the joins, which are revealed by ageing and by the loss of the finish; the V-shaped pieces at the corner, the joint of which is covered by the applied leaf, are also clearly visible.
In this feather-patterned frame from the collection of the Metropolitan Museum, the mould used to produced the separate pieces of pastiglia is estimated to have been about 5 ¾ inches long (or 14.6 cm), the frame itself is 17 7/8 x 16 ¼ outside, and 12 ½ x 10 ¾ inches at the sight (45.4 x 41.3, and 31.8 x 27.3 cm) . The carved wooden mould was thus relatively small, and would have been re-used innumerable times, making the finely-detailed finish worth its labour. The retention of such fine detail in the pastiglia itself is due to the ingredients used in its confection.
British compo, common from the late 18th century onwards, is made of whiting (or powdered chalk), rabbit-skin glue, linseed oil, resin, and Venetian turpentine, which is mixed into a warm, beige-coloured dough and pressed into oiled moulds. When it is taken from the moulds it is dry but still slightly flexible, so that it can be bent around the members of a frame; it dries out completely over a very long period, finally becoming brittle and flaking away from the base, as can be seen in so many Victorian frames. French plaster is much whiter, and is made of gesso grosso mixed with a skin glue high in collagen, which renders it less likely to flake and split. It is very similar in its ingredients to Renaissance pastiglia, and like pastiglia it is capable of retaining very fine detail, as can be seen in 19th century French Salon frames, with their multiple orders of enrichment.
Giovanni Bellini, St Jerome reading…, detail
There are many other recipes for types of composition which have been used at various periods, but the process used on the frame of Bellini’s St Jerome would, as with the much later French Salon frames, have been similar to what is described in Il libro dell’ arte, the 15th century handbook by the artist Cennino Cennini. This is a fascinating compendium of techniques of all sorts for the Renaissance artist, including drawing, painting, preparing panels, grinding colours, gilding, varnishing, and taking life masks, amongst many other things. (It also includes moral advice, warning the art student against ‘indulging too much in the company of woman’, as this is bound to end in shaky hands). The Libro dell’arte was translated in 1933 by Daniel V. Thompson as The Craftsman’s Handbook, and reissued by Dover Books in 1960; Dover Books have kindly given permission for the relevant passages on making gesso and preparing an ancona with moulded ornament to be published here.
Cennino Cennini’s The Craftsman’s Handbook, translated by Daniel Thompson, and republished by Dover Books in 1954 & 1960, from the original, published by Yale University Press in 1933. Courtesy of Dover Publications, Inc.
Daniel Thompson translates the Italian tavola as a ‘panel’, but retains ancona to describe a panel with an engaged frame, probably with ornamental mouldings. This is obviously slightly different from the moveable, portable 15th – 16th century pastiglia frame, but the processes involved were similar and would remain so for some time. Many of the pictures set in pastiglia frames were in any case small panel paintings, so that the net product was very like what Cennino describes.
The Craftsman’s Handbook
How you should start to work on panel or anconas: Chapter CXIII
Now we come to the business of working on anconas or on panel. To begin with, the ancona should be made of a wood which is known as whitewood or poplar, of good quality, or of linden or willow. And first take the body of the ancona, that is, the flats, and see whether there are any rotten knots; or, if the board is greasy at all, have the board planed down until the greasiness disappears; for I could never give you any other cure.
See that the wood is thoroughly dry; and if it were wooden figures or leaves, so that you could boil them with clear water in kettles, that wood would never give you any trouble with cracks.
Let us just go back to the knots or nodes, or other defects which the flat of the panel may display. Take some strong leaf glue; heat up as much as a goblet or glass of water; and boil two leaves of glue in a pipkin free from grease.
Then have some sawdust wetted down with this glue in a porringer. Fill the flaws of the nodes with it, and smooth down with a wooden slice [spatula], and let it stand. Then scrape with a knife point until it is even with the surrounding level. Look it over again; if there is a bud, or nail, or nail end sticking through the surface, beat it well down into the board. Then take small pieces of tin foil like little coins, and some glue, and cover over carefully wherever any iron comes; and this is done so that the rust from the iron may never come to the surface of the gesso. And the flat of the ancona must never be too much smoothed down. First take a size made of clippings of sheep parchment, boiled until one part remains out of three.
Test it with the palms of your hands; and when you find that one palm sticks to the other, it will be right. Strain it two or three times. Then take a casserole half full of this size, and the third part water, and get it boiling hot. Then apply this size to your ancona, over foliage ornaments, canopies, little columns, or any sort of work which you have to gesso, using a large soft bristle brush. Then let it dry.
Next take some of your original strong size, and put two coats over this work with your brush; and always let it dry between one coat and the next and it will come out perfectly sized. And do you know what the first size, with water, accomplishes? Not being so strong, it is just as if you were fasting, and ate a handful of sweetmeats and drank a glass of good wine, which is an inducement for you to eat your dinner. So it is with this size: it is a means of giving the wood a taste for receiving the coats of size and gesso.
How you should put a cloth on a panel: Chapter CXIV
When you have done the sizing, take some canvas – that is, some old thin linen cloth, white threaded, without a spot of any grease. Take your best size; cut or tear large or small strips of this canvas, sop them in this size, spread them out over the flats of these anconas with your hands; and first remove the seams; and flatten them out well with the palms of your hands, and let them dry for two days. And know that this sizing and gessoing call for dry and windy weather. Size wants to be stronger in summer than in winter. Gilding calls for damp and rainy weather.
How the flat of a panel should be gessoed with the slice, with gesso grosso: Chapter CXV
When the ancona is quite dry, take the tip of a knife shaped like a spatula, so that it will scrape well, and go over the flat. If you find any little lump or seam of any sort, remove it.
Then take some gesso grosso – that is, plaster of Paris, which has been purified and sifted like flour. Put a little porringerful on the porphyry slab, and grind it with this size very vigorously, as if it were a colour. Then scrape it up with a slice; put it on the flat of the ancona, and proceed to cover all the flats with it, with a very even and rather broad slice; and wherever you can lay it with this slice you do so. Then take some of this same ground-up gesso; warm it, and take a small soft bristle brush and lay some of this gesso over the mouldings and over the leaves, and likewise over the flats gessoed with the slice. You lay three or four coats of it on the other parts and mouldings, but you cannot lay too much on the flats. Let it dry for two or three days. Then take an iron spatula and scrape over the flat. Have some little tools made which are called ‘little hooks’, such as you will see at the painters’, made up in various styles. Shape up the mouldings and foliage ornaments nicely, so that they do not stay choked up; get them even; and contrive to get every flaw in the flats and gap in the mouldings repaired by this gessoing.
How to make the gesso sottile for gessoing panels: Chapter CXVI
Now you have to have a gesso which is called gesso sottile; and it is some of this same gesso, but it is purified for a whole month by being soaked in a bucket. Stir up the water every day, so that it practically rots away and every ray of heat goes out of it, and it will come out as soft as silk. Then the water is poured off, and it is made up into loaves and allowed to dry; and then this gesso is sold to us painters by the apothecaries. And this gesso is used for gessoing, for gilding, for doing reliefs, and making handsome things.
How to gesso an ancona with gesso sottile, and how to temper it: Chapter CXVII
When you have done the gessoing with gesso grosso, and scraped it nice and smooth and evened it up well and carefully, take some of this gesso sottile. Put it, loaf by loaf, into a washbasin of clear water; let it soak up as much water as it will. Then put it on the porphyry slab, a little at a time, and without putting any more water in with it, grind it very thoroughly. Then place it neatly on a piece of strong white linen cloth; and keep on doing this until you have taken out one loaf of it. Then fold it up in this cloth, and squeeze it out thoroughly, so as to get as much water out of it as possible. When you have ground as much of it as you are going to need, which you must consider carefully, so as not to have to make gesso tempered in two ways, which would not be a good system, take some of that same size with which you tempered the gesso grosso. Enough of it wants to be made at one time for you to temper the gesso sottile and the gesso grosso. And the gesso sottile wants to be tempered less than the gesso grosso. The reason? – because the gesso grosso is your foundation for everything. Nevertheless, you will naturally realize that you cannot squeeze the gesso out so much that there will not still be some little water left in it. And for this reason make the same size, confidently.
Take a new casserole, which is not greasy; and if it is glazed, so much the better. Take the loaf of this gesso, and with a penknife cut it thin, as if you were cutting cheese; and put it into the casserole. Then pour some of the size over it; and proceed to break up the gesso with your hand, as if you were making a batter for pancakes, smoothly and deftly, so that you do not get it frothy. Then have a kettle of water, and get it quite hot, and place the casserole of tempered gesso over it. And this keeps the gesso warm for you; and do not let it boil, for if it boiled it would be ruined. When it is warm, take your ancona; and dip into this pipkin with a good-sized and quite soft bristle brush, and pick up a reasonable amount of it, neither lavish nor skimpy; and lay a coat of it all over the flats and mouldings and foliage ornaments. It is true that for this first coat, as you are applying it, you smooth out and rub over the gesso, wherever you lay it, using your fingers and the palm of your hand, with a rotary motion; and this makes the gesso sottile unite well with the gesso grosso. When you have got this done, begin all over again, and apply a brush coat of it all over, without rubbing it with your hand any more. Then let it stand a while, not long enough for it to dry out altogether; and put on another coat, in the other direction, still with the brush; and let it stand as usual. Then give it another coat in the other direction. And in this way, always keeping your gesso warm, you lay at least eight coats of it on the flats. You may do with less on the foliage ornaments and other reliefs; but you cannot put too much of it on the flats. This is because of the scraping which comes next.
How you may gesso with gesso sottile without having gessoed with gesso grosso first: Chapter CXVIII
Furthermore, it is all right to give any small-sized and choice bits of work two or three coats of size, as I told you before; and simply put on as many coats of gesso sottile as you find by experience are needed.
How you should temper and grind gesso sottile for modelling: Chapter CXVIV
There are many, too, who just grind the gesso sottile with size, and not with water. This is all right for gessoing anything which has not been gessoed with gesso grosso, for it ought to be more strongly tempered.
This same gesso is very good for modelling up leaves and other productions, as you often need to do. But when you make this gesso for modelling, put in a little Armenian bole, just enough to give it a little colour….
[Chapters CXX-CXXIII deal with scraping down the dry gesso and preliminary drawing on the panel surface, so are omitted here]
How to model on a panel with gesso sottile, and how to mount precious stones: Chapter CXXIV
After this, take some of that gesso for modelling, if you want to model any ornament or foliage ornament, or to mount any precious stones in any special ornaments in front of God the Father or Our Lady, or any other special embellishments, for they add greatly to the beauty of your work. And there are glass gems of various colours. Arrange them systematically, and have your gesso in a little dish over a pot of hot ashes, and a little dish of hot clear water, for you have to wash the brush out often; and this brush is to be of minever, quite fine and rather long; taking up some of the warm gesso neatly on the tip of this brush, briskly set to modelling whatever you please. And if you are modelling any little leaves, draw them in first, as you do the figure. And do not try to model many of them, or too many complicated objects; for the clearer you make your foliage ornaments, the better they respond to stamping with the rosette, and they can be burnished better with the stone. There are some masters who, after they have modelled what they want, apply one or two coats of the gesso with which they gessoed the ancona, just the gesso sottile, with a soft bristle brush. But if you model lightly, in my opinion you get a finer, stronger, surer result by not putting any on, by the system which I stated earlier – of not putting on several types of gesso tempera.
How you should cast a relief for embellishing areas of anconas: Chapter CXXV
Since we are on the subject of modelling, I will tell you something about it. With this same gesso, or some stronger of size, you may cast a lion’s head, or any other impression taken in earth or in clay . Oil this impression with lamp oil ; put in some of this gesso, well tempered, and let it get quite cold; and then lift up the gesso at the side of the impression, with the point of a penknife, and blow hard. It will come out clean. Let it dry. Then apply some in embellishments in this way. With a brush, smear some of the same gesso with which you do the gessoing, or some of that with which you model, wherever you want to put this head; press it down with your finger, and it will stay in place neatly. Then take some of the gesso and lay a coat or two of it, with the minever brush, over the part which you are modelling, and rub over this casting with your finger; and let it stand. Then feel over it with a knife point, to see whether there are any little lumps on it, and remove them.
This last chapter of Cennini’s handbook is obviously the most relevant for pastiglia frames and their moulded ornament. It is interesting that Cennino’s moulds are made of clay; if lions’ heads are being cast, it would of course be much the easiest course to model one and cast it in clay (or wax, which Thompson specifically rejects as a possible translation). However, with a length of very fine and regular ornament like guilloche, carving a reverse mould from a hard wood does seem to be the method most likely to give a detailed result and a tool capable of being used many times.
Cassetta frame with pastiglia relief, 1500-50 (c) Victoria and Albert Museum, London.
As we have seen, the strips of pastiglia on the feather-patterned frame in the collection of the Metropolitan Museum were approximately 5 ¾ inches long (or 14.6 cm). In the case of the frame in the collection of the V & A, which is decorated with grotesques, the description of the applied ornament notes that:
‘…on the left and right, the lengths of relief decoration are cast from the same mould. Each length runs from the top to the bottom edge of the frieze and covers the mitres. The diagonal cracks through the cast work at the corners have appeared as a result of movement in mitre joints in the wood below. The top and bottom lengths are placed between the side lengths and are cast from a different mould. At the top and bottom of the frieze, the vertical joins in the cast work can be seen near the corners. At the top corners, a rectangular piece of relief decoration with masks and drapery has been set into the cast work’ 
Technical analysis of the pastiglia found that it was made of gypsum (plaster of Paris, or Cennino’s ‘plaster of Volterra’), and that ‘the presence of animal glue’ was also indicated. In other words, it is made from precisely the mixture of gesso and size that Cennino describes. When the National Gallery acquired the frame used for Rapahel’s Madonna of the pinks, the composition of the pastiglia ornament was similarly analyzed, and also found to contain ‘animal glue, chalk and traces of linseed oil’ (information from Peter Schade).
Cassetta frame with pastiglia relief, reverse. Victoria and Albert Museum, London.
This is the reverse of the same pastiglia frame in the V & A; it is described thus:
‘The frame is made up of a back frame and a front frame made of softwood. The back frame is roughly finished with lost knots and is half lap jointed. At the back, the vertical members are lapped over the horizontal members. The front frame includes the sight edge moulding and is mitred. The outer moulding is mitred and applied’.
The Louvre possesses an example of a pastiglia frame with grotesque ornament similar to that in the V & A (Giovanni Bellini, Christ Blessing, c.1465-70); one motif – the double spray of leaves and an upturned bellflower supported on a band with Greek fret – is identical, but the figures and animals are not. The structure of the Louvre frame is not a simple cassetta but an aedicule, created by the attachment of a base moulding and an entablature at the top.
There are three examples of pastiglia cassetta frames in the National Gallery, Washington, on which Steve Wilcox, the Senior Conservator of Frames has kindly commented.
Attributed to Antonello da Messina, Portrait of a young man, c.1475-80, Andrew W Mellon Collection 1937.1.31. National Gallery of Art, Washington
Steve Wilcox: The frame on the Antonello da Messina has a new back moulding, and the whole thing appears to have been cut down. It also seems to have been regilded. There is no record of when the frame was put on this painting.
Alvise Vivarini (1442/1453-1503/05), Portrait of a man, c.1495, Samuel H. Kress Collection 1939.1.355. National Gallery of Art, Washington
Steve Wilcox: The back frame retains sliding dovetail joints on all four corners, and the face mouldings are mitred. The gilding is old, and possibly original. There is no record of when this frame was put on the painting.
Giovanni Bellini (c.1430/1435-1516), Portrait of a young man in red, c.1480, Andrew W. Mellon Collection 1937.1.29. National Gallery of Art, Washington
Steve Wilcox: The back frame retains sliding dovetail joints at all four corners; the face mouldings are mitred. The pastiglia is butt-jointed; there is some regilding at the corners. A small slip was added to accommodate the present painting; the frame was put onto it in 1975. It is is part of a collection of frames owned by the Samuel H Kress Foundation, and sent to the National Gallery of Art in 1961.
As well as this small group of pastiglia frames with guilloche ornament, and the even rarer examples with feather patterns or grotesques, there is another clutch of frames, related not by their method of production but by their decoration. These are the frames which have the same structure and guilloche on the frieze, but which are made of carved wood.
Antonello da Messina, Portrait of a man, c.1475-76. National Gallery NG1141
One of these is in the collection of the National Gallery, London. This was acquired in Basel, and consisted of four lengths of carving which had been assembled as a frame without possessing an original back frame; it might therefore originally have been part of a spalliera (the framed painting or decorative panel on top of a cassone), or of a cassapanca (a Renaissance carved bench with back and arms).
Tuscan carved walnut cassapanca, detail, 2nd half 16th century. Christie’s, King Street, 5 November 2009, Lot 238
Antonis Mor, Portrait of two canons, 1544. Gemäldegalerie, Berlin
Other examples include the Antonis Mor, above, in the Gemäldegalerie; this appears to have much more the authentic structure of a frame, and the frieze is finished at the corners with carved acanthus leaves.
Titian (Tiziano Vecellio), Italian, c.1485-90–1576; Christ Shown to the People (Ecce Homo), c.1570–76; oil on canvas; 43 x 37 5/16 in. (109.2 x 94.8 cm); Saint Louis Art Museum, Museum Purchase 10:1936
There is also this superb, rather later example on a Titian in Saint Louis: a parcel-gilt walnut frame with supporting leaf moulding at the back edge, fluting at the sight edge, and small runs of beading and enriched astragal mouldings. The frame has been altered to fit this painting: the astragal moulding does not meet perfectly at the bottom corners, particularly at the lower right. Similarly, the wooden guilloche frame on Signorelli’s Martyrdom of St Catherine of Alexandria, 1498, in the Sterling & Francine Clark Art Institute, has been altered to fit the painting. The existence of these carved wood analogues of the pastiglia frames, and the possible connection of both with carved borders on pieces of Renaissance furniture (the spalliera and casspanca), indicates that there was a relationship between the elements of an interior even at this early period, and that frames may have been designed or chosen to fit with the furniture in a particular room.
There may be many more of these charming frames, both the pastiglia and carved wood versions, lurking in private collections or hanging in other museums and palazzi (see also the Städel, Frankfurt, and San Diego Museum of Art; there is another in the Museo Horne, on a School of the Marches portrait of Federigo II, Duke of Urbino; information courtesy of Paul Mitchell). However, their comparative rarity as against other cassetta patterns enhances both their charm and their desirability for – especially – the small Renaissance portrait or sacred scene. The National Gallery’s reframed Bellini is an instance of the expert eye alighting on the perfect solution, and recreating the painting like a jewel in its new setting.
With many thanks to Peter Schade of the National Gallery for providing the images and information used in this article; thanks also to Steve Wilcox of the National Gallery of Art, Washington; to Dover Books for permission to quote large passages from Cennini’s Il Libro dell’Arte; and to Michael Hilliard of Perceval Designs for the series of photos on preparing size and gesso.
National Gallery frames: an interview with Peter Schade > here
National Gallery reframings: Mannerist frames > here
National Gallery: reframing Mantegna> here
Reframing the Renaissance: Museums and Madonnas> here
National Gallery exhibition: Sansovino frames> here
On Tuesday, 4th November 2014 (1.00-1.45 pm), Peter Schade is giving a talk with Caroline Campbell on the reframing of Giovanni Bellini’s St Jerome Reading in a Landscape.
 Of course, there are other forms of non-flat decoration, such as punchwork, and ornament built up freehand from liquid gesso applied by brush.
 Timothy Newbery, George Bisacca, Laurence Kanter, Italian Renaissance frames, 1990, The Metropolitan Museum of Art; no.68.
 Thompson’s footnote to Cennini: ‘The original is ambiguous here. I understand it to mean: “Add half as much water as you have size,” as Cennino’s rules usually call for a total of three “parts”. The point has little practical significance in this case.”
 Thompson’s footnote: ‘Giesso grosso cioe Volteriano: That is, “coarse plaster, of Volterra”. Perhaps Cennino’s plaster was no more Volteriano than ours is Parisian!’
 Thompson’s footnote: ‘The phrase che e purghato may be introduced in L. [the 18th century MS which is one of the sources of this translation] through error, or through confusion by the scribe of gesso grosso with gesso sottile, anticipating the directions of Chapter CXVI. R [another source MS] gives quite a different reading: “ … gesso grosso… which is purified like flour; and, when sifted, put a little porringerful…”.’
 Thompson’s footnote: ‘Raffietti: These are made nowadays in Italy under the name of raschiaii. The so-called “plaster tools” of the sculptors, made of bronze or steel, may be pressed into service, but a set of raschiaii, with blades shaped to meet the requirements of mouldings, carvings, pastiglia, etc., mounted at right angles to shafts and handles of convenient shape, will lighten and expedite the work enormously. The modern practice of “drawing up” the gesso as it is applied, with cut pumice templets, and smoothing off after the gesso is dry with the same templets and water, produces a rather mechanical perfection, and is not applicable to carved ornaments.’
 Thompson’s footnote: ‘Modelling executed on the gesso surface with gesso applied with a brush is now generally called pastiglia ( See Chapter CXXIV, …, below). The addition of a little colouriong matter makes it easier to see the beffect of the work as it progresses. The modern trade equivalent for “Armenian bole” is “Gilders’ Red Clay”, or “Red Burnish Gold Size”.’ The Frame Blog comment: Thompson’s use of pastiglia here is nothing to do with the pressed or moulded and applied strips of dough-like material which are the subject of this article. It is much more like a wet slip (as in clay modeling), which is painted on to the surface and built up progressively in layers. Its effect is very soft and in shallow relief: see Chapter CXXIV, below.
 Thompson’s footnote: ‘See Chapter CXVIV. …, above.’
 Thompson’s footnote: ‘R [one of the source MSS] has cera, “wax”…
 Thompson’s footnote: ‘Olio da bruciare: a vegetable oil, probably olive oil, of inferior quality.
 Christine Powell and Zoë Allen, Italian Renaissance Frames at the V & A – A Technical Study. Elsevier Ltd. in association with the Victoria & Albert Museum, London, 2010, no. 16.