The Technique of the Mosaic Art


How two mosaics were made for
St George’s Orthodox Church, Houston, Texas

Aidan Hart

It all began with an email from Father James Shadid, the priest of St George’s Orthodox Church. His parish was extending its church, and he wanted two large mosaics of the Crucifixion and the Resurrection to fill the new east walls created by the renovations. Thanks to the marvels of the internet, he had found on my website a mosaic that my assistants and I had only just completed for St Martin’s in Cardiff, Wales. Right there and then he decided that he wanted us to make his church’s mosaics.

500,000 hand cut tesserae later, my assistant Martin Earle and I were ready to fly to Houston, Texas to install the two massive mosaics, each measuring 4.9 x 3.6 metres (16 x 12 feet). It had been a two year journey from design to this day. 

How did we make them? I had taken a course under Luciana Notturni in Ravenna and learned from her what I call the double direct method. Unlike the reverse technique, this method allows the mosaicist to lay the tesserae directly and therefore to bed them at the optimum angle to achieve the maximum play of light.

The tesserae are set directly into a temporary bed of lime putty in the studio. We used smalti from Orsoni and gold from Dona Murano. When the work is completed an open weave cloth is glued on top with animal glue. The mosaic is then pealed from its temporary panel and the lime removed from its back. Mortar is spread both on this back and on the permanent surface (wall or panel), then the two gently pressed together. We used Mapei’s Adesilex P10 with their Isolastic plasticizer, with the addition of a fine fibre. We also coloured the different areas of adhesive to match the corresponding area of mosaic: red behind the gold; blue-black behind blue mosaic, and so on. When the adhesive is fully set the cloth is removed with hot water and scrubbing.

Our mosaics were so large that we made each work in about fourteen sections. The supporting panels were Aerolite, a super light but very stiff sandwich system developed for the aerospace industry. It is made of aluminium honeycomb sandwiched between two layers of glass fibre enforced epoxy resin. The edges of our “jigsaw’ pieces corresponded to the edges of the figures, so no joins arbitrarily ran through garments or flesh parts. 

These panels, all 900kg of them, were then carefully crated and air freighted to St Georges. My assistants and I then spent a month screwing these to the prepared wall and carefully filing with smalti the spaces that we had deliberately left around the joins. Absolutely no joins were apparent in the end. 

So much for the technical stuff. What principles did we apply making the mosaics? I have been a professional icon painter and church artist for over thirty years, working in egg tempera, fresco, stone and wood carving, and for the past five years, mosaic. Although the work I do is clearly inspired by Byzantine painted icons, mosaic is a different medium. I believe strongly that one should design and make a work using the particular strengths and limitations of the medium at hand – and it is usually understanding the limitations that is the key to success.

  •  The andamenta (the lines created by the bedded tesserae) need to be fully expressive of the work, elegant and rhythmical, so that if the mosaic were all in white one could still clearly see the subject.
  • The angle as well as the placement of the tesserae is important. The gold tesserae at Houston were four to six metres from the floor, so we angled most of these downward as much as 30 degrees, and also left and right to create a sparkle.  And although to a lesser degree, we likewise varied the angle of the coloured smalti to create natural variations in the colour’s shades.
  • Regarding faces, hands and feet, the darker lines are crucial to give expression, in particular the eyebrows, upper eyelid line, the ends of the lips, and the outlines of the finger and feet. Any subsequent modelling can only embellish this expression: it cannot redeem bad drawing. 
  • Economy of cut. At least with Roman and Byzantine work, the tesserae are more or less the same size, and sort of square with very few rectangles, and they reserve triangles for areas or special treatment. The only exception to the same-size rule are flesh areas, where they will often use smaller tesserae than the garments, to allow greater nuance of expression. But even so, within these flesh areas the tesserae or more or less the same size and mostly square-ish.
  • I say sort-of square, because there is a perfect imperfection to Byzantine masterpieces. The irregularity of the hand cut tesserae – disciplined in overall size but relaxed in particulars – reflects nature. Just as the leaves of an oak are all recognizably oak-like, each is nevertheless different. Although each of our gold tesserae roughly filled a 10 x 10mm square, they actually varied in side length from 7 to 13mm.