Atelier saint André Painting fresco


Colors - The range of colors for the fresco is very large (see the color table)). However only mineral-based colors are used as the lime "burns" the organic and vegetable colors
- Colors are diluted in water and they must have a precise consistency. If too much water is used, the intensity of the colors is diluted while if too little water is used, they will go on the support as paste.

- the white that is used for fresco is a lime wash which can be done as follows :
  • to one liter of water add one kilo of lime
  • stir the mixture and let stand overnight,
  • the following day, remove the water and collect the white paste.

Drawing (see Byzantine style)

A fresco must be executed rapidly. As a result any corrections to the drawing waste invaluable time and the possibility to make such corrections is limited. The drawing should be in its finished state, both on paper as well as in the artist's head, and it should be ready to apply to the wall.

Calq - Begin with a reduced scale drawing
- Do color studies that will refine the harmony of colors for the whole composition.
- Make a full scale drawing in charcoal on a large sheet of kraft paper.
- If the fresco is very large, subdivide the drawing the drawing into sections that can be handled each work day.
- Using titanium white on the full-scale drawing, determine the placement of the highlights.

Transfer the drawing

Transferring - Test the fresco coat by pressing it with your finger before transferring the drawing. The coat should resists the pressure of the finger.
- Using a plumb bob (this can be made using a string that is soaked in color), locate the center and exterior dimensions of the soace onto which the drawing will be transferred.
- The bob or string is used like a rubber band that has been tightened between two anchors and pulled out and released thus striking the wall. This leaves a trace of color on the wall
- Align the drawing to the wall and secure it.
- Transfer the drawing onto the support by engraving the lines into the coat. Use the tip of the handle of a brush to trace the lines through the kraft paper. This leaves a light mark in the fresh coat.

Stages of painting

Fresco painting requires a good organization :

- Colors and brushes should be within easy reach on stable working surfaces.
- Set out several containers of clean water in which to wash the brushes.
- Colors should be prepared in advance and put in small labeled containers.
- Paint from the top down in order to control drips and stains from damaging the lower parts of the painting.
- Colors will become clearer as they dry.
- The coat that will appear to be grey when it is wet will become white when it dries.
- Test the colors on paper to determine what the colors will look like when dry.

Trinity 2

Trinity 3

  • The frame should be painted with a red color, i.e. Venice red.
  • Trace in the main lines with a diluted color.
  • Apply color in transparent layers to each area according to their covering capacity (see the color table) :
    • one layer for ochres as they are a high covering pigment,
    • two or three layers for earth greens,
    • two or three layers for ultramarine blue, the emerald green, red and yellow,
    • four or five layers for cobalts as they tend to turn white,
    • the lime-wash mixtures become very white after drying
  • Wait for five minutes between two layers.
  • To keep the same intensity of color be sure to dry off brushes well.
  • Depends upon the weather, the season, the humidity in the air, one can smooth the colored areas separatly.
  • The base for the flesh tone is a mixture of chromium oxide green and a little yellow ochre.
  • Retrace the lines of the drawing in umbers and begin the modelling with a color that is a little stronger than the local color.

Trinity 4 Trinity 5 Trinity 6

  • Use the local color mixed with a little of the lime-wash and titanium white to lighten parts of the fresco .
  • Draw the lines in the flesh using red or Venice red and black.
  • Model the areas of the flesh to be lightened with a layer of red ochre. Leave the parts of the flesh that will not be lightened in green (the red is used as a transition between the green and the yellow ochre of the following enlightenment).
  • Lighten the flesh tones with yellow ochre mixed with a little red ochre. In layers reduce the areas toward the area of greatest light.
  • After each layer, blur the enlightenment areas, using an almost dry brush, by "melting" the colors to obtain a progressive gradation of tones.
  • Redraw and finish modeling.
  • Put in the final highlights on the fresco with lime-wash. These should include the flesh, the outer frame as well as the inscriptions.


  • If defects occur during the painting process, scrape the area with a trowel to remove the part to be repaired. Then rebuild the surface and begin painting again. This is only for minor repairs and must be done with great care and discretion. If serious defects appear in the fresco, it is preferable to remove the entire surface coat, rebuilt it and to paint it from the beginning.

  • A smoothed coat gives more solidity to the fresco. A coat that raises, cracks or splits shows signs of being applied to tightly, to feebly, or prepared with too much moisture. Or perhaps the rough coat under the painting layer was too dry when the top coat was applied.

  • However one should not come to the conclusion that the fresco must be hard like marble, because behind the crust or skin of the paint, the coat remains relatively flexible. This gives it the ability to absorb or reject ambient moisture and to always conserve a little of the same quantity of water. If fresco cannot breathe it will become too dry, crumble and become detached in pieces.

  • Deterioration of the mortar is caused by a bad quality of lime or sand, from a bad quality hydrated lime, through badly filtered or sifted lime. Cracks or fissures are caused by bad slaked limes or from an excess of water.

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Last update : Fri, Jan 9, 2009, P. Grall © ASA 2000 - 2009 All rights reserved.