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粉彩探源

热度 1已有 771 次阅读2021-1-18 13:04 |个人分类:科学实验

2021-1-17

雍正十三年（1735）大清督陶官唐英在他所撰写的《陶务叙略碑记》一文中对洋彩做了解释：洋彩器皿，本朝新仿西洋珐琅画法，人物、山水、花卉、翎毛无不精细入神。乾隆八年，清高宗乾隆命唐英将景德镇御窑厂官窑制作过程，以图文并茂方式加以记载，写成了《陶冶图册》一书，说景德镇御窑厂就是洋彩的制作与完工地点。

那么洋彩究竟是个什么东东呢？

所谓的洋彩，就是粉彩（Famille Rose），是道教老祖宗们鼓弄了好几千年百思不得其解的真正的点金术，被十七世纪经历过工业革命后的德国（一说荷兰）人轻而易举就给破解了，于是康熙皇帝便欣喜若狂，惊为天人，迅速引进到宫廷珐琅器和瓷器生产中。Alice Min 在《紫啊紫》（In the Pink）一文中说，洋彩就是卡西乌斯紫（Purple of Cassius）也就是四氯化锡，传统上又叫紫金粉或胭脂红，是氯化金和氯化亚锡化学反应的产物，也是自大清雍正时期卡西乌斯紫在中国瓷器生产中的应用，于是就出现了变化多端不拘一格的粉彩瓷器。

It all began in 1650 with a Dutch chemist Andreas Cassius, who first discovered a formula allowing for the creation of pink glaze. His secret was a purple-toned mineral, known most appropriately forever since as Purple of Cassius. The colours conceived through his experimental persistence weren’t just pink and purple, but pale rose, coral red, mauve, salmon, lavender blue.

十五世纪德国鬼子淘金图

Chinese ceramists quickly (for the seventeenth century) caught wind of Cassius’ developments, and the first famille rose pieces began appearing during the relatively short reign of Emperor Yongzhen from 1723-1736. Things fully matured under his successor, Emperor Qianlong whose lengthy rule from 1736-1796 was closely knit with the profitable exchanges that took place between Orient and Occident during the era.

于是才形成了中国瓷器中唯一可以和青花瓷平分秋色的粉彩瓷：

雍正粉彩盘
乾隆粉彩茶壶

常言说，没有金刚钻，不揽瓷器活。粉彩形成的关键，是要先有氯化金，又称三氯化金，最简单的方法是把金矿石和王水反应，生成氯金酸[H(AuCl4)·4H2O]，才是点石成金的关键：

Au + HNO3 + 4HCl → H(AuCl4) + NO↑ + 2H2O

也可以直接在高温中氯化该金属，形成氯化金：

2Au + 3Cl2 → 高温 → 2AuCl3

再于酸性溶液中给低浓度的氯化金滴上几滴氯化亚锡，就可以点石成金，形成无色无嗅的四氯化锡，和游离状态的单质金：

2AuCl3 + 3 SnCl2 → 2Au↓ + 3SnCl4

可是四氯化锡极不稳定，会水解形成氢氧化锡:

SnCl4 + 4H2O→ Sn(OH)4 + 4HCl

在溶液中呈胶体游离状态的单质金吸附于氢氧化锡的表面，就形成了呈现亮紫颜色的所谓的桂皮紫。金含量越高，紫颜色就越深，这就是在欧洲风行了好几个世纪的检测矿石中是否含有黄金的秘密武器，也是玻璃生产中宝石红玻璃的秘密配方。

A solution of Stannous Chloride called “Purple of Cassius” has been used for centuries by gold prospectors to test for the presence of gold in a solution. It would give them a rough idea of how rich the gold is in the ore deposit. This is determined by the color of the reaction that could range from a light pink to a dark purple. The darker the purple, the richer the gold ore.

Purple of Cassius is a purple pigment formed by the reaction of gold salts with tin(II) chloride. It has been used to impart glass with a red coloration (i.e. stained windows), as well as to determine the presence of gold in a sensitive chemical test.

维基百科有关卡西乌斯紫的介绍中，说卡西乌斯紫是卡西乌斯发明的：

Purple of Cassius is a purple pigment formed by the reaction of gold salts with tin(II) chloride. It has been used to impart glass with a red coloration, as well as to determine the presence of gold as a chemical test. Generally, the preparation of this material involves gold being dissolved in aqua regia, then reacted with a solution of tin(II) chloride. The tin(II) chloride reduces the chloroauric acid from the dissolution of gold in aqua regia to a colloid of elemental gold supported on tin dioxide to give a purple precipitate or coloration. When used as a test, the intensity of the color correlates with the concentration of gold present. This test was first observed and refined by a German physician and alchemist, Andreas Cassius (1600–1676) of Hamburg, in 1666.

但事实并非如此，卡西乌斯也不是最早发现卡西乌紫的人。因为早在罗马帝国晚期，西方就有了用金制红玻璃的技术，即是使用胶体金（colloidal gold）的发色，把奈米级别的金粒子悬浮于液体之中，由于金粒子的形状、大小不同，生产出来的玻璃所呈紫红颜色也略有差异。到了1659年，德国化学家约翰格劳伯（Johann Rudolf Glauber）开始用用氯化亚锡还原金盐的化学方法配置紫金粉了。随后不久，在普鲁士，约翰孔克尔（Johann Kunckel）就把这种技术应用到宝石红玻璃生产中了，通过加入氯化金成功烧制出一种红色玻璃（Goldrubinglas ，金红玻璃）。后来的维也纳化学家因为揭示了其中的化学原理，获得了诺贝尔化学奖。也就是说，卡西乌斯紫的发明是历史上诸多化学同人不懈努力的结果，并和红宝石玻璃的生产和应用有关：

Although there were hints of the pigment that would eventually be called Purple of Cassius as early as the 15th century, its history really begins in 1659, when the alchemist and chemist Johann Rudolf Glauber prepared a “brilliant purple-colored powder” by reduction of gold salts with tin chloride.

德国化学家约翰格劳伯（Johann Rudolf Glauber，1604-1670）

Glauber had many interests, among which were glass production and the use of solutions of gold for medicinal purposes, but he never seemed to have explored the addition of his purple powder to glass. That advance was left to the chemist and glassmaker Johann Kunckel (1630–1703).

普鲁士化学家约翰孔克尔（Johann Kunckel，1630–1703)

Kunckel was aware of Glauber’s work, and in 1679 produced gold ruby glass from his glass works in Potsdam. He described the formation of a purple precipitate from the addition of metallic tin to a solution of gold in aqua regia, essentially Glauber’s procedure, in his Laboratorium Chymicum, which was not published until after his death (1716). Kunckel produced a variety of ruby glass on a commercial scale, although few pieces that can be definitively assigned to him survive.

Six years after Kunckel started producing gold ruby glass, the physician Andreas Cassius (1645–ca. 1700) published De Auro, a book that described what becomes known as “Purple of Cassius”—the same material earlier prepared by Glauber and used by Kunckel. Cassius did not pretend to be the first to use the gold-based pigment, but his was the name forever associated with it.

In the seventeenth century, beautiful glass which came to be known as 'ruby glass' from its colour, was first made in Potsdam in Germany. The recipe for making the colouring pigment or stain was published in 1685 by Andreas Cassius, and ever since then the colour has been called Purple of Cassius. The recipe was costly, for it involved dissolving fine gold powder in aqua regia, adding water, and then adding a piece of pure tin. After an hour or two, a brilliant purple precipitate formed, Purple of Cassius.

Many famous chemists in the eighteenth and nineteenth centuries attempted to understand the nature of Purple of Cassius, but it was a Viennese chemist, Richard Zsigmondey, who finally found the answer: the gold is in colloidal form, adsorbed on a base of stannous hydroxide. For his work on the nature of colloids, Zsigmondey was awarded the Nobel Prize in 1925.

维也纳化学家Richard Zsigmondey（1865-1929）因为揭示了粉彩的化学机理获1925年诺贝尔化学奖

卡西乌斯紫在瓷器上面的应用，不仅仅是景德镇一家。德国的梅森早在1719年就开始使用这种技术了，早于景德镇生产的粉彩。法国塞维斯和其它欧洲瓷器厂家生产的高档瓷器，至今还都有卡西乌斯紫的身影。由于卡西乌斯紫在瓷器上是低温（700摄氏度以上）成彩，相对于高温(800摄氏度)下形成的青花、单色釉和五彩硬瓷，所以老外又称雍正粉彩为软彩、洋彩或珐琅彩。尽管粉彩和珐琅彩的生产工艺，也不完全相同（珐琅彩中含有大量的硼砂作为融剂，而粉彩中也使用传统五彩中的矾红）。

Purple of Cassius was used in some of the most world-famous porcelain from Meissen, and Sevres, and the art of making it travelled to China where it was used from 1723 in Chinese Famille Rose porcelain. The presence of gold explains its extremely high cost, but it has immense colouring power and is still used today in very high quality tableware.

Purple of Cassius is a powerful colorant as well as a beautiful one, and it will yield a range of purple, red, and pink colors that can be used in enameling and to decorate ceramics. The solution was so powerful that, despite the use of gold, it was not prohibitively expensive. One of Jean Hellot's correspondents noted that one gros of gold could make 49 gros of purple color when prepared for ceramic painting; if application is measured in numbers of brushstrokes, this could decorate a very large number of pieces.

Famille rose (French for pink family) is a type of Chinese porcelain first introduced in the 18th century and defined by the presence of pink colour overglaze enamel. It is a Western classification for Qing dynasty porcelain known in Chinese by various terms: fencai, ruancai, yangcai, and falangcai. The colour palette was introduced in China during the reign of Kangxi by Western Jesuits who worked at the palace, but perfected only in the Yongzheng era when the finest pieces were made.