Revealing blue light on a 19th-century Chinese helmet decorated with Tian-tsui

In preparation for the major redisplay of National Museums Scotland’s East Asian collection opening in 2019, I have been conserving the ceremonial helmet and armour of Zhang Chaofa, admiral and governor of the Zhoushan islands, China, from 1830 to 1840.

Front and back views of the main body of the helmet before conservation.
Front and back views of the main body of the helmet before conservation.

The ceremonial parade armour was confiscated by the head of British armed forces during the capture of the island of Chusan, in one of the first major battles between Britain and Imperial China in the Opium Wars of the 19th century.

The plume before conservation
The plume before conservation.

The armour came to National Museums Scotland from the leader of the British forces at Chusan, Lieutenant-General George Burrell, by way of James Young Simpson, the Edinburgh-born doctor and medical pioneer, when he donated it to the Society of Antiquaries of Scotland in 1860. It became part of the permanent collection in 1956.

Sir James Young Simpson. Image via Wikimedia Commons.
Sir James Young Simpson who donated the helmet to the Society of Antiquaries in 1860. Image via Wikimedia Commons.

The helmet for the suit of armour is made up of a silvered metal cap with gilt copper-alloy mounts decorated with dragons and phoenixes. A gilt metal dome sits on top to hold an elaborate plume, and a curtain of gold brocade, bordered with black velvet and ornamented with copper-alloy studs, hangs underneath to cover the neck. Lining much of the helmet and armour decoration are gold and silver papers. There are four detachable four-clawed dragons that sit front and back of the helmet, and two phoenixes which flank either side – all are made of gilt copper-alloy.

Other examples of similar types of Qing helmets and armour in Britain are at the Royal Armouries, Leeds, and the British Museum.

Examples of Qing dynasty armour at the Royal Armouries (left, image (c) Royal Armouries ) and the British Museum (right, image CC BY-NC-SA 4.0).
Examples of Qing dynasty armour at the Royal Armouries (left, image © Royal Armouries) and the British Museum (right, image © British Museum CC BY-NC-SA 4.0).
The gilt dome and attachments for the helmet before conservation.
The gilt dome and attachments for the helmet before conservation.

For the front and back of the helmet there are two elaborate copper-alloy attachments in the shape of dragons, with twisted gilt and silver wires, glass and paste beads, gilt paper and silver gilt tails, leaves and scrolls with tian-tsui decoration. Literally meaning ‘dotting with kingfishers’, tian-tsui is an ancient Chinese decorative style which uses kingfisher feathers glued onto silver gilt. The effect is rather like cloisonné enamel use in Europe, but with an even more striking blue colour.

Qing helmet
An example of a Qing helmet plume from the 17th-18th century with elaborate tian-tsui decorated attachments on two eagle feathers. This example comes from the Metropolitan Museum of Art, in New York (image public domain).

Kingfisher feathers have no blue pigment in them; they are actually brown in colour. The blue we see is a result of structural colouration. The blue barbs of the feathers contain spongy nanostructures with slightly different dimensions, causing different reflectance spectra. The feathers scatter blue light by a process called the Tyndall effect: the structure of the feathers reflects back blue light, which reaches our eyes and leads us to perceive the familiar blue. This is the same process by which we see the sky as blue.

Two detachable ornaments for the helmet in the shape of dragons before conservation. Of gilt copper-alloy with leaf and scroll ornaments with wire, glass and paste beads, and tian-tsui decoration.
Two detachable ornaments for the helmet in the shape of dragons before conservation, made from gilt copper-alloy with leaf and scroll ornaments with wire, glass and paste beads, and tian-tsui decoration.

The armour consists of a tunic, skirt, skirt front, shoulder pieces, arm pieces, and square pieces of gold brocade with blue silk and black velvet and embroidery, and two circular medallions of silver metal. As an artefact conservator, I have been working on the metalwork and attachments for the helmet and armour. A textile conservator, Danielle, has been working on the brocade, velvet and silk of the armour.

One of the silvered metal medallions before conservation.
One of the silvered metal medallions before conservation.
The right shoulder attachment of the armour, with gold brocade, blue silk, black velvet, copper-alloy studs and gilt decorative attachments, before conservation.]
The right shoulder attachment of the armour, with gold brocade, blue silk, black velvet, copper-alloy studs and gilt decorative attachments, before conservation.

When it arrived in the Artefact Conservation lab this spring, the metalwork of the helmet was in a fair condition overall. There were some tarnishing and spots of corrosion on the copper-alloy elements, and a lot of surface dust from storage. The helmet had previously been lacquered, as revealed with UV light.

The helmet under UV light showing the lacquer.
The helmet under UV light showing the lacquer.
Two of the plain dragon attachments of the helmet under UV light.
Two of the plain dragon attachments of the helmet under UV light.

The kingfisher feather details of the tian-tsui decoration and silver ornaments were looking a lot worse for wear. There was much surface dirt and dust obscuring the details of the decoration and concealing the kingfisher feathers, preventing their blue reflectance. There was a significant amount of loss of kingfisher feathers too, with some feathers being stuck back on at odd angles, and evidence that losses had been ‘repaired’ in the past with green paint/paste.

Hidden blue: one of the gilt decorations of the dragon attachment before conservation showing the kingfisher feathers and green paste.
Hidden blue: one of the gilt decorations of the dragon attachment before conservation, showing the kingfisher feathers and green paste.

After testing, the old iridescent lacquer was removed from the silver metal surface with cotton swabs of acetone, and then the of the main body of the helmet, gilt metal dome, brass mounts and studs were surface cleaned with cotton swabs of alcohol and deionised water and degreased with swabs of white spirit. Surface cleaning revealed, hiding underneath all the dust, red-painted paper on the peak of the helmet and gilt paper in between the decoration of the gilt dome. The gold decorated paper surfaces between the decorative elements of the peak of the helmet and gilt dome were cleaned with swabs slightly moistened with alcohol and deionised water, under magnification. The red painted paper was dusted with a soft hair brush and vacuum tweezers.

The brass studs and gilt attachments on the brocade neck curtain. These were cleaned with solvents, and so the brocade had to be protected whilst cleaning was in progress.
The brass studs and gilt attachments on the brocade neck curtain. These were cleaned with solvents, and so the brocade had to be protected whilst cleaning was in progress.

Some of the gilt copper-alloy attachments for the helmet and armour were suffering from spots of corrosion and accretions. These were manually removed with a scalpel under magnification and the areas of corrosion treated with a corrosion inhibitor before being sealed with an acrylic consolidant.

Copper corrosion on the gilt attachment on one of the shoulder pieces of the armour before treatment.
Copper corrosion on the gilt attachment on one of the shoulder pieces of the armour before treatment.
The shoulder piece after the removal and treatment of active copper corrosion.
The shoulder piece after the removal and treatment of active copper corrosion.
An accretion on the underside of one of the gilt decorations on the dragon attachment.
An accretion on the underside of one of the gilt decorations on the dragon attachment.
After the accretion has been removed, revealing the copper-alloy surface underneath.
After the accretion has been removed, revealing the copper-alloy surface underneath.

The tarnish on the silver medallions was treated with a Pleco pen. This uses electrolytic reduction to reduce the silver sulphide tarnish back to silver metal. This means abrasives, a common way to remove tarnish, do not have to be used and so no original material is lost.

The Pleco pen set up to reduce the tarnish on a silver lid from another object in the East Asian collection.
The Pleco pen set up to reduce the tarnish on a silver lid from another object in the East Asian collection.
One of the silver medallions after conservation.
One of the silver medallions after conservation.

The elaborate tian-tsui dragon attachments were the trickiest parts to conserve for the helmet, comprising of many different elements which needed to be treated individually. The kingfisher feathers were cleaned under the microscope with cotton swabs and soft sable brush moistened with alcohol and deionised water.

Cleaning individual kingfisher feather barbs under the microscope.
Cleaning individual kingfisher feather barbs under the microscope.

The feathers pulling away from the metal attachments were reshaped by wetting them with deionised water the manipulating them with tweezers and vacuum tweezers. Once clean and their original blue iridescence revealed, the feathers were consolidated and re-adhered in place to the metal surface. The twisted wire coil decorations were carefully detangled from the main copper-alloy body of the dragon attachments and those wire coils which had come loose were recoiled.

Blue revealed: one of the gilt decorations of the dragon attachment after the kingfisher feathers have been cleaned.
Blue revealed: one of the gilt decorations of the dragon attachment after the kingfisher feathers have been cleaned.
One of the dragon heads after the kingfisher feathers have been treated.
One of the dragon heads after the kingfisher feathers have been treated.

The small glass and paste beads, wires and copper-alloy elements were all cleaned with cotton swabs of alcohol and deionised water, and the gilt paper surfaces cleaned with cotton swabs slightly moistened with deionised water. The underside of the attachments are lined with paper, so these paper surfaces were dusted with a soft sable brush to remove dirt and debris. The lifting paper edges were re-adhered to the underside of the copper-alloy body with methyl cellulose in deionised water and alcohol. One of the tian-tsui dragon attachments had a detached tail decoration, and so this was reattached to the wire under the main body of dragon with acid-free polyester fabric adhered around the wire to strengthen the join.

Reattaching kingfisher feather barbs.
Reattaching kingfisher feather barbs.
The two dragon attachments with tian-tsui decoration: on the left post-cleaning, on the right before cleaning.
The two dragon attachments with tian-tsui decoration: on the left post-cleaning, on the right before cleaning.

Next to conserve for the helmet was the elaborate plume attachment, which secures to the top of the gilt dome. This consists of heavily ornamented gold and silver gilt copper-alloy, silvered paper, glass beads, bamboo cane, marten fur, coral, eagle feathers and more tian-tsui. This was dismantled to allow a thorough assessment and treatment of all the various materials.

The plume attachment for the helmet with close up of the feather and tian-tsui before conservation.
The plume attachment for the helmet with close up of the feather and tian-tsui before conservation.
The gilt copper-alloy elements of the base of the plume taken apart for conservation.
The gilt copper-alloy elements of the base of the plume taken apart for conservation.

As with the rest of the helmet, the gilt copper-alloy elements of the plume were cleaned with solvents and any active corrosion removed and treated. The kingfisher feathers on the copper-alloy were cleaned, consolidated and reattached where loose. As with the helmet attachments, this was a very fiddly business which required a lot of time hunched over a microscope. But the change in colour from dusty feathers to clean was wonderful to see. The silver paper was dusted with a fine hair brush and dry cotton swabs, and any loose paper was re-adhered back in place onto the inside of the gilt copper-alloy domes. The marten fur was dusted using a hairbrush and museum vacuum on low suction, with the nozzle covered with gauze to prevent any loss of material.

The eagle feather attachments after conservation.
The eagle feather attachments after conservation.

During cleaning, one of the threads of glass beads became loose. This thread was strengthened and reattached to the bead net with new cotton thread, of near similar colour, which was tied to original thread, wound around and bound to it.

The loose bead thread with new cotton thread to strengthen it (left) and then the thread reattached (right).
The loose bead thread with new cotton thread to strengthen it (left) and then the thread reattached (right).

The eagle feathers were cleaned with a soft brush: they were brushed in the direction of the growth of feathers towards a museum vacuum cleaner nozzle, covered with a piece of gauze, on low suction. The feathers were first manipulated by hand to rearrange the barbs back into place. Further manipulation was done after the barbs were relaxed by light steaming, and then straightened into their proper place. Feathers are a keratin material, a type of protein, and chemically related to hoof, horn, scale and nails. The protein chains of keratin are associated to each other by hydrogen bonding and most hydrogen bonds are interrupted at 40 to 60°C, which is why steam is often used to relax keratin materials. Fragile barbs at the tip and near the stem of one feather were strengthened by attaching them to a neighbouring barb with tiny spots of adhesive, performed under a microscope, to prevent their loss.

Fragile feather barb at the tip before (above) and after (below) strengthening.
Fragile feather barb at the tip before (above) and after (below) strengthening.
Kingfisher attachments
The Kingfisher attachments.

Once the conservation treatments were complete, it was time to reassemble the helmet and plume and see the tian-tsui decoration in all its blue glory.

The complete helmet

The attachments after conservation.
The helmet and attachments after conservation.
Plume and feather attachments after conservation.
Plume and feather attachments after conservation.

To see the completed conservation work, come and see the helmet, the rest of Zhang Chaofa’s armour and other treasures from China and East Asia when our new Exploring East Asia gallery opens at the National Museum of Scotland on 8 February 2019!


Find out how you can be part of the story of our new galleries by donating to our Museum Transformation appeal here: www.nms.ac.uk/transform.

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