Panel in machined and shot peened state

The machining of the panels was carried out by Birmingham based Delcam UK using a CADCAM computer controlled milling process. Unfortunately, much of their work is for defence contractors, and as such is classified so I have no pictures to show this part of the process. I can, however, explain the process.

Plates are the solid panels out of which the image will be machined, and is 25mm aircraft grade aluminium. These are uncut at this stage so that the image can be centrally located in the plate.

The drawings seen on the mosaic page are scaled to the full size of the plate, which is 100cm wide in all cases. Using the drawings, tooling paths are calculated using the CADCAM software, and these paths are fed as vectors to the milling machine. The computer controlled jig goes over the surface of the the plate, and bit by bit, machines out the recesses so that, after about 14 hours, the lines of the drawing stand proud and the white bits of the drawing are recessed to 9mm. The plate is cut to the correct size and shape, making it a panel, and then is moved forward to the next part of the process.

This was performed by The Metal Improvement Company here in Newbury. The panels in their raw machined state, although full of detail are covered in machine oil and the edges are very sharp. Shot peening (a kind of sand blasting but much more controlled) removes these sharp edges and degreases the panel ready for the mosaic work to begin.

This is panel 10 in the studio ready to have the Venetian glass applied.

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Planning each panel

Panel 12 on a bench on the studio at the beginning of the mosaicing stage.

Using a colour guide obtained from the glass suppliers and the 'smalti' sorted into individual jars, the building phase is planned for each panel. Here we see the owl it a very early stage, these colours and patterns being continued from the previous panel.

At the top of the picture can be seen a couple of the jars with the appropriate colours and the tile nippers used to shape the glass pieces.

2 or 3 panels were worked on at any one time; one for visiting and 2 in the studio.

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Cement is applied

The cement used is a 2 part resin based type suitable for outdoor use in extreme weather conditions. It is highly aggressive and had to be handled with the utmost care; hence the gloves; and has a working life of about 1-2 hours before it starts to cure and become unusable. The cement, which takes about 24 hours to set, and reaches full strength after 1 week, is virtually impregnable; even the manufacturers don't know how to remove it.

In order to accurately apply the cement to the desired areas only, I developed a piping bag technique, seen here. What you can't see are the goggles and face mask, also essential for long exposures to the cement vapours.

It is, however, quite safe to use for short periods with the correct precautions in place, such as suitable ventilation, barrier cream and careful hand washing.

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Cement is applied (continued)

A painters palette knife is used for more delicate areas. Note the smalti in place at the bottom of the picture

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Cutting the glass

The Venetian glass smalti is cut using special tile nippers. By offering the pieces up to the place where they are destined to go, it is possible to determine whether a cut is required. The smalti is gripped in the nippers and by applying the right pressure, a clean break can be achieved.

Waste pieces are collected up for possible use in the future.

The shards of glass that invariably fall are kept off the panel by using cloths to protect the surface, in a similar way to how a surgeon would isolate the area to be worked on. Other shards are hoovered up.

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Cleaning each complete area

As each part of a panel is begun, so it must be completed in a disciplined and methodical way. It is very difficult to flit from one part to another and the use of the cement is time sensitive.

This is a completed area being cleaned prior to the cement being allowed to cure undisturbed. Note the cloth on the left of the picture protecting the surface of the mosaic, the hoover and needle to clean unwanted shards away, and the electric toothbrush used to polish away drying cement before it hardens and gets too difficult to remove.

In the background is a segment of a full sized drawing used to work out and plan the colours and patterns.

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Panel 3 in progress

Panel 3 well along the road to completion. In the foreground is the colour guide; and note the labels denoting possible colours for the blank areas. Further in to the build phase I wrote in each area with indelible pen to prevent others from moving the labels around.

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