This page entitled “Special Patinas” is an except from the book “Japanese Patinas” written by Eitoku Sugimori. This is a list of Japanese Special Patinas.
Wara-ibushi patina is used to achieve a dark brown-to-black color over a base of niage or su-tanpan patina. The first step in the process creates a sticky layer of tar on the prepared metal object, and the second step deposits soot that is bound by this layer. This description follows the traditional method, but it is also possible to create the soot in several ways. Pour oil (motor oil, olive oil, peanut oil, etc.) into a small dish that is sitting on a heat resistant surface. The size of the dish and amount of oil will depend on the size of the object. Ignite the oil and hold the work in the smoky flame to coat it with soot.
It is also possible to create soot with an oxy-acetylene torch. Reduce the proportion of oxygen (“starve” the flame), perhaps even to the point where you are burning the fuel gas by itself. This will create a lot of soot, both on the work and in the air, so it is best to work outside.
Safety Note: Work outdoors or in a well-ventilated place. This process produces a lot of smoke, therefore, a mask or respirator is recommended.
In the nuri-iro patina, a thin layer of Japanese lacquer ( urushi ) is applied to the metal to glue soot onto an object. This patina is applied onto a base coat of niage or su-tanpan , resulting in a glossy black surface.
Urushi is the sap of the urushi tree, a member of the poison sumac family. The sap, when exposed to the atmosphere, hardens, but also has extremely irritating affects when coming into contact with skin (like poison ivy only worse). When handling urushi , rubber gloves are essential. The following process also requires the heating of urushi , of which the evaporating steam and smoke should not be inhaled.
You must wear a respirator when applying this patina.
This process (translated as “painted copper”) does not fit into our usual definition of patina, but it is closer in concept to the surface we use on our cars. A high quality lacquer is colored with pigments, then carefully applied. Originating in China , iroe -do was popular in Japan for a short time at the end of the Edo period. Though commercially-made lacquer can be used, urushi is valued and favored for its strength. This is a final finish that is applied once the piece has been polished.
In separate dishes, make a few different lacquer mixtures using urushi and pigments. These should be thinned to make a paste that can be painted on with a brush. Apply the colors with a high quality brush, then allow the work to air dry. It is critical that no dust is in the environment; set the work in a closed box that will allow air to enter but keep contaminants out. A frame with fabric panels is useful.
When the urushi is dry, polish the surface, then seal it with wax or clear lacquer.
Safety Note: To protect against skin irritation caused by contact with urushi , always wear rubber gloves when handling the lacquer.
Ryuka patina is used to create a gray, dark gray, and black patina on silver and copper alloys. It behaves in a way similar to liver of sulfur, a compound familiar to metalsmiths in the West, who use it to color sterling, fine silver, and copper. In effect (though not in chemistry), ryuka is similar to gun bluing, a commercial product that can be used to create a gray and gray-brown on bronze.
Mix up a quantity of this solution in advance, then add a small amount to warm water as needed. Ryuka patina creates a black patina on copper, brass, and silver.
Combine the dry ingredients and grind them to a powder. Bring the liter of water to a boil in a stainless steel pot, and add the dry mixture. Stir thoroughly. Let the solution cool, then transfer it to a glass or plastic container for storage.
A similar effect can be obtained by applying the ryuka solution directly onto the surface with a cloth. Different results can occur depending on the strength of the solution, so for consistent results it is important to keep the ratios of solution to water the same each time.
Furubi patina is applied to silver and silver alloys (such as sterling), to create rich browns and grays associated with age. The first variation, kin- furubi ( kin means gold) creates a rich amber patina and the second recipe below, gin- furubi ( gin means silver) achieves colors that transition through gray to black.
The traditional kin- furubi recipe is a mixture of pure gold and aqua regia , a potent acid that dissolves the gold. In the interest of safety, that recipe is replaced here with a commercially available solution that contains the same ingredients: gold dissolved into a liquid solution, mixed with alcohol, which will allow it to evaporate quickly. Gold plating solutions are sold by most suppliers of jewelry equipment.
Furubi solutions are used mainly on silver. The following three patinas will produce a black or dark purple color.
Process: Immerse the object until the color changes. Remove and wash with baking soda. Dry with a soft cloth and apply wax to seal the patina.
Process: Apply with a brush or by immersing the work until the color changes and follow the finishing procedure as above.
Process: Apply with a brush or by immersing the work until the desired color is achieved. To finish, polish with baking soda and seal with wax.
When using furubi solutions containing strong acids, wear eye protection, rubber gloves and work in a well-ventilated area. Always wash your hands and work area thoroughly after using the solutions.
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