To create this work we relied on the fresco technique, which consists of painting on fresh plaster with pigments diluted in water, so that the pigments during the process of carbonation of the lime, are incorporated into the plaster forming a whole, in a cohesive relationship and therefore no longer removable.
In our case we reproduced, thanks to the support of the teacher Umberta Trevellin, a decorative band of a ceiling of Palazzo Cordellina in Vicenza, an eighteenth-century palace frescoed by Paolo Guidolini and Girolamo Ciesa from 1784 to 1789.
Preparation of the drawing
First, after receiving the image to be created, we adapted the dimensions of the drawing, until we enlarged it to cover the dimensions of the support, an eraclit panel (a material composed of wood wool used in construction as a sound absorber, light and suitable for maintaining humidity), in order to create a continuous band by placing all the panels made by the class together.
We made some pencil tests to study the shapes and the chiaroscuro and a watercolor color test to preliminarily study the colors and then we organized ourselves to create the sheet for dusting the suitable measurements for the eraclit panel.
We transferred the drawing in pencil onto a sheet of paper, and then punched it with an awl, following the drawing, with equidistant holes about 5mm apart.
To punch holes in the dusting cardboard, you need to be careful not to make the holes too close together or too far apart: if they are too far apart, you may not be able to distinguish the subject well once you have dusted the support, especially for complex drawings. If the holes are too close together, you may tear the sheet between the holes, dirtying the support with too much dust. It is also important to create references in the dusting, such as for horizontal lines and always clean the sheet after dusting.
It is always a good idea to do a dusting test on another surface before doing the final dusting, to see if the drawing is reproduced optimally.
The color of the dusting pigment must also be decided based on the surface that will receive it: in our case, since the background of the drawing was dark, we created pads with light pigment.
The color test with pigments
To prepare ourselves to work with pigments we made a color test on a sheet of stiff paper, trying to get the colors as faithful as possible to the original.
First we laid out the dark background band on which the festoon of leaves, flowers and fruit would be placed, making it with raw umber and burnt umber in a ratio of 3:1.
As a binder for the pigments we used gum arabic diluted in water in a ratio of 1:8.
On this test surface we tried to test the pigments, always with gum arabic binder.
It was the first time I painted with pigments and it was very interesting to observe the different coverage of the various shades, for example of the green earth, which is not very covering.
It was interesting to try to use the pigments in various consistencies, more or less diluted,
see how they dust when there is too little gum arabic and learn to use them very diluted to obtain the right transparency.
Doing this color test was really useful.
I also tried a different subject from the one chosen for my panel, to try different colors and different shades, better refining the technique.
Preparing the mortars for the support
We were also able to dedicate ourselves to preparing the support by simulating a plastered wall, creating the roughcast, the plaster and the background color for the fresco.
The roughcast is a background mortar, in our case made with slaked lime and aggregates in a ratio of 1:3, aggregates composed of cocciopesto and sand in a ratio of 1:2.
We wet the Eraclit well before spreading the arriccio (the surface that receives a
mortar must always be wet, as well as the tools, especially if they are wooden like the trowel) otherwise the water contained in the mortar would be immediately absorbed by the Eraclit, causing the plaster to dry too quickly.
We spread the arriccio in two layers, a first thin layer, pressing, to make the mixture penetrate the Eraclit and therefore make it stick well, then a softer layer, then smoothed with the trowel to obtain flatness. In the end the total layer was about 1 cm.
These are the tools used:
- the trowel, which is used to collect the mixture from the bucket, place it on the trowel and then pick it up to “throw” it onto the support and spread it
- the trowel, which can be made of wood or metal, which is used to hold the mortar while you are plastering and then to smooth it out
- the sponge trowel which is used to smooth out more accurately
- a brush to wet the support
The work with the trowel must be done in areas, starting for example from the bottom left and then proceeding, with all the thickness, towards the top right.
We left the surface of the rough plaster to be able to accommodate the plaster.
Once the rough plaster was dry, we proceeded with the plaster.
The plaster was prepared with slaked lime and aggregates in a ratio of 1:2, and the aggregates were yellow sand from Tuscany and grey sand from the Po in a ratio of 1:2.
We brushed the rough plaster with a brush to remove the dust, we wet it and we spread a layer of plaster of about 5 mm, of creamy consistency, always in 2 layers, one crushed and one softer, then smoothing it with the sponge trowel.
We also modelled the edges well, helping ourselves with a wet sponge, making the corners round so that they they split less easily.
Once the plaster had started to set, we spread the background color, which we had prepared previously.
We composed the background color with slaked lime, yellow ochre, Venetian red, raw umber and a touch of cobalt.
We learned that for example Giotto did not coverthe plaster with a background color, but he let it show through the figures, he pulled the color with the iron to bring out the lime putty and then be able to color more calmly. We spread the background color as a sort of skimming to make the plaster uniform, make the mortar more solid and delay the drying time. The water of the background color is gradually absorbed and we realize when it is time to start painting.
On the background color we marked the horizontal lines, taking the measurements, with a nail, an important operation to have uniform references in all the panels made, which make up the band.
The same measurements were present in the dusting sheet, so as to always be able to perfectly align the drawing to the panel.
At this point, when the background began to pull, we created the dark background of the band on the support, using burnt umber, thus starting to work on the fresco.
To go straight on the edge of the band, we started to learn how to use the stick with the brush suitable for fresco, which is also called line drawing pen.
This is a brush without metal parts, made of pig bristles, suitable for fresco and mezzo fresco painting.
For me it was a new and particular tool that I had never used, I was used to simple synthetic brushes and initially I did not get along well with the bristles that are stiffer, I felt like I could not get the effects I wanted.
However, it is a matter of becoming familiar with the technique, since fresco painting is very different from painting in watercolour on a sheet of paper or in oil. Once you get the hang of it and understand the process, the line brush is an irreplaceable tool.
Near the lower and upper edge of the brown band, we sponged the color to obtain a more jagged and wavy effect.
We then began to paint the green base of the band, covered with leaves, with a green that was as common as possible to everyone, composed of green earth, natural umber and natural sienna.
On this green base we carried out the dusting to see the outlines of the leaves and flowers, and in my case also of the central bow.
This is how the painting phase began with different shades of green to give shape and volume to the leaves.
Initially I had difficulty because I tended to use the pigments with too little water, fearing that they would not be covering well.
In this way, however, I would end up with too much layer of pigment and therefore with the color flaking and cracks.
Once I understood the correct procedure and became a little more familiar with the diluted color, I was able to give the right effect and trust a freer brush stroke and gestural.
I learned that the color lightens a lot, and I also compared myself with the addition of lime, such as white, or titanium white, observing how the lime lightens. Only experience can make you understand and intuit what the result can be up toale in fresco painting, because what we see when it is just spread with the brush, can be very close to the final result.
It is interesting to discover how to obtain a shade, for example orange, by mixing pigments such as Venetian red and yellow ochre, but also obtaining the same shade through glazes.
Some pigments, such as green, are not very covering, with others instead you risk insisting too much, obtaining a dirty effect and marking the shadows too much.
I learned to apply the color very diluted, to change its tone with glazes, as well as to create shadows by adding raw umber to the base color.
Interesting to see how the shapes acquire volume through the shades of shadow and then the final highlights.
I also noticed how the pure pigments are very bright and very covering even when working with the light on the dark.
Once you have taken a a little familiarity is a job, the fresco, that has given me a lot of satisfaction.
The lower band
After having created the band with the leaves, flowers and fruits in fresco, several days passed, so in the lower band of the panel, populated by rosettes and moldings, we proceeded almost dry. Almost because the plaster cannot be said to be completely dry after a few days, but it can be said that we worked with a technique halfway between dry and half-fresh.
The half-fresh technique in fact consists of always using pigments diluted in milk of lime on plaster. In this case the pigments are no longer incorporated into the plaster that carbonates as in the fresco technique itself, but remain attached to the surface through the same calcium hydrate combined with the pigment, which carbonates.
In order to use pigments without lime, therefore purer, we used casein as a binder, dissolving it in lime milk in a ratio of 1:10, which thus becomes calcium caseinate.
The stamping
To create the rosettes of the lower band we adopted the stamping technique, which consists of creating a mask in rigid and oily paper, so that it does not absorb liquid and can be cleaned, and then stamping the pigment on the mask, with a brush with a blunt tip.
The mask is made by cutting out the surfaces that will receive the color with a scalpel or cutter, masking the rest so that it does not get dirty.
It is important to clean the mask well between one step and the next, so as not to smudge the edges and dirty areas that should not receive color.
It was interesting to discover how a cardboard covered in linseed oil can become an excellent sheet from which to obtain masks.
For the base color of the rosettes we used the background color of the panel already made, adding natural Cyprus earth and natural umber.
Then 5% calcium caseinate should be added to the color to make it adhere to the plaster.
The density of the background color of the rosettes should be kept quite thick, to avoid the risk of it passing under the mask, smudging the design.
With yellow ochre we then created the center of the rosette, and then proceeded with lights and shadows.
For the roses we used three main colors for all:
- the background gray of the roses, obtained as already mentioned from the background color of the panel with the addition of natural Cyprus earth and umber
- an intermediate grey for the mid-tones, for the lighter shadows and for the lines and shades of the panel, adding raw umber, cyprus earth and burnt umber.
- a dark one for the shadows, also adding ultramarine blue
- a white with titanium white for the highlights
We have created these colors common to all the panels, to make the result uniform.
Once the roses were made, we moved on to the molding lines and their shades, first practicing a lot with a stick and a drawing pen to learn how to draw straight lines and shades.
After becoming familiar with the tools, we created the horizontal lines and the shades on the panel.
For the shades you can proceed either using the almost empty brush of color, “fraying” the color, or with very diluted pigment.
It was very interesting to learn how to create the shades, also because the color is immediately absorbed into the support, but I learned to keep in mind that the result must be seen on the wall from afar, so it is more important to convey the idea from afar than to work hard up close.
The last step before to consider the work finished, was to standardize the color tones of the various panels, especially in the blue of the bows and in the horizontal lines of the rosette band, which would have been the most noticeable breaks in the event of differences.
It was therefore nice, through teamwork, to let go of the result of “my” work, in favor of an overall result that is beautiful to see regardless of who created it.
In general, I really liked the technique, it was very interesting to finally discover in practice the difficulties and advantages behind this ancient technique so much admired as the fresco.
