Also called suikin. It is a type of overglaze pigment used in the finishing of ceramics and porcelain decorations, and is mainly used for Western tableware, but has also been used in Japan for a long time on Kutani-yaki and other highly colored ceramics. The main ingredient is an oil-soluble terpene (gold compound), to which several metals such as rhodium, bismuth, nickel, and chromium are added in the form of resin salts to increase the adhesiveness and heat resistance of the gold film. The resulting product has a blackish-brown, slightly viscous oil-like appearance, and when patterned on a ceramic surface with a special fine brush or rubber stamp and fired in a furnace at 700 to 800 degrees Celsius after drying, it produces a brilliant, solid golden film of gold. However, if it is applied to a porous product, it does not produce a gold film but a purple color. There are two types of gold solution, one for ceramics and the other for glass, depending on its use. Commonly used types are red gold, blue gold, vanishing gold, and NW gold. Red gold has a slightly reddish hue and contains about 1% gold, and is considered the standard product. Both NW gold and vanished gold have a higher gold content than red gold, and vanished gold is used for the highest-grade items, as the gold film is polished with special sand after firing to produce a deep, pear-like luster. The use of gold solution is said to have started with Kühn of Meissen, Germany, in 1830. However, in reality, the gold solution was exclusively imported from England and Germany, and when World War I broke out in the early Taisho period (1912-1926), imports were halted, causing great consternation. At that time, Jiro Ishikawa of Nippon Toki Co., Ltd. succeeded in the industrial production of mizu-gold for the first time and saved the country from this crisis. Ltd. also began to produce excellent products, and now all products are made in Japan.
