Nhat Tran | About Urushi

The Origins of Urushi

The oldest lacquer artifacts found were in Japanese tombs from 6,000 years ago, while in Vietnamese tombs archaeologists have found many lacquered objects dating back to the fourth century B.C. Urushi (the Japanese name for lacquer) is a viscous fluid organic material that comes from the milky sap of several varieties of an Asian tree belonging to the Anacardiacea family. Nearly all Southeast Asian countries have a variety of their own: in Japan, it is the Rhus vernicifera; in Cambodia, it is the Rhus Malanorrhea. Vietnam, too, has its own varieties, the most reputed being the Rhus Succedanea. Urushi should not be confused with industrial synthetic coatings that are used to impart a high gloss to surfaces.

The Process of making urushi paintings

Making an urushi painting is a long and demanding process. It may take several months, depending on the specific technique of the artist, the number of urushi layers that are applied, and atmospheric conditions that are favorable enough for the lacquer to cure.

Priming

After the sap has been tapped, it is boiled, skimmed, and filtered through a hempen cloth to remove impurities. It is then stored in wooden barrels for several weeks and graded according to the age of the tree, the season it was collected, and the depth at which it separated after maturation.
Urushi is a medium with remarkable qualities. It is highly resilient and durable thanks to its biochemical properties (how its enzymes react both with oxygen and with proteins in order for urushi to cure and harden). Before painting begins, the support (plywood or polystyrene) is primed with ten layers of lacquer mixed with very fine clay.
As a result, it becomes very resistant, water-proof, insect-proof, and mold-proof, and the support is prevented from cracking, bending, or warping under fluctuations of temperature or humidity. Urushi also has strong adhesive properties: any material added to it binds with it permanently. In addition, it provides a rich array of esthetic effects of textures, dimensions, layers, colors, light, and shine.
Urushi products can last hundreds of years while retaining their glossiness, smoothness and elegance. Their colors do not fade with the impact of light and time, and amazingly, as the years go by and the pieces age, their colors keep getting deeper and become more luminous.
Artists mix urushi with color pigments and various natural dyes. Other embedding materials can be used, such as eggshell, mother-of-pearl, plant fibers, sand, and gold and silver leaf.

Painting and Wet Sanding

Good priming is a long and arduous process, but essential to ensure long-term durability. Before urushi painting can begin, the support needs to be primed with ten coats of lacquer. Each coat must completely cover the support: front, back, and sides. Each of these coats needs to cure completely and then be sanded before the next one is applied.
The support is first painted with persimmon tannin to seal the surface and facilitate absorption, and then sanded. A first layer of raw urushi is applied and then sanded after it has dried.
Thin sheets of hemp cloth are soaked in raw urushi and attached to cover tightly all sides of the support. A new layer of raw urushi is applied and then sanded after curing.
Subsequently, a foundation layer of urushi is applied mixed with ground clay. Four more such coats mixed with a decreasing ratio of ground clay and an increasing ratio of pulverized clay stone are then applied. Two more layers of raw urushi are applied to finalize the priming.
Once fully cured, the support is sanded and polished. When fully primed, the support is pitch black, perfectly smooth, and permanently protected against decay or damage caused by water, acids, heat, insects, and mold.

Polishing

The last stage is the polishing of the work, which takes the following steps.

If a particular design is needed, it is first drawn with chalk on the fully-primed support.
The artist will then start to apply layer after layer of a higher grade urushi mixed with different colors (at least five coats in average, often much more, with curing and sanding taking place between each).
Mixing the dry pigment with urushi is time-consuming because both must be stirred together thoroughly and then filtered.
On some layers the artist applies extremely thin leaves of silver or gold to create background effects of light. Tiny pieces of crushed eggshell may be embedded with tweezers, one fragment at a time, wherever white color or a mosaic effect is needed.
Once no more additional layers or materials need to be applied, and once the work has again completely cured, the extremely delicate task of “painting by wet sanding” begins. This is an artistically risky and crucial step, for upon it depends the final external appearance of each painted panel. Using very finely grained sand paper (of a grade ranging from 400 to 2,000) and a constant flow of water on the surface, the artist begins “digging” into the layers, moving carefully her hand inch by inch, taking at every moment the decision to continue or stop sanding according to what pattern develops all around and to the textural effects she is determined to achieve. The artist must remember in what layer a particular color has been applied and must be careful not to sand too hard or too quickly to avoid passing through the desired layer and thus spoiling the painting. Specific color nuances can only be achieved by carefully sanding the interface between a given pair of layers.

Finishing

First, the entire surface is wet-sanded with a very fine grain of paper and cleaned with clear water.
Then the same process is repeated with san-jet (an abrasive powder).
Using a piece of fine silk wrapped around a cotton ball, a very thin layer of a finishing urushi of the highest grade is applied in round motion, throwing away the silk as soon as it gets dark. The work is then put inside a muro (urushi-curing chamber) to let it cure.
After sanding, five layers of the clearest variety of urushi are applied to serve as a clear-coat protector.
Finally, the entire surface of the work is polished by rubbing it first with either a soft cloth or the bare palm of the artist’s hands until adequate depth of appearance and a wonderful sheen is obtained.

Care

The surface of clear lacquer is protective and durable. The only maintenance the artwork needs is dusting with a light soft feather duster or a soft dry cloth. If necessary, urushi paintings can be cleaned with almost anything that is not abrasive or harsh. Fingerprints can be removed by rubbing with a soft damp cloth and the surface needs to be dried immediately with a soft dry towel. A mild soap or alcohol can be used to remove stickier dirt. Rinse well with clear water and dry immediately with a soft paper towel.

No polishing or varnishing product should be applied to the paintings. If desired, one can easily polish the painting again with the palm of the hand to make it cleaner and shinier.