Was milk first added to tea cups in order to protect delicate porcelain from cracking under the heat of hot water?
Maybe. It depends when the teacup was made and who made it.
All early china teapots and cups, whether sitting on tea tables in London or Boston, were imported from China. Tea drinkers in England waited nearly a century to see the first domestic tea wares – other than silver – appear on their tables.
English factories first produced porcelain in the 1740s. The attempt to equal that being made in China – and on the Continent – was a matter of national pride. The problem was that the Chinese had been making porcelain for centuries. Asian potters had long ago perfected the making of a teapot and cups that would stand up to hot water.
Unfortunately, early English porcelain makers constantly fielded complaints from customers whose teapots or cups had cracked when boiling water was placed in them.
An advertisement in the October 28 1760 edition of the The Leeds Intelligencer touted the goods of a firm by the name of Robinson and Rhodes, “…a good assortment of Foreign China and a great variety of useful of English China of the newest improvement, which they engage will wear as well as foreign, and will change gratis if broke with hot water.’
The London manager of the Derby factory regularly received complaints from dissatisfied customers. He wrote to the company office in 1780 that he “…wished something could be done respecting the teapots to prevent them flying, for the disgrace is worse than anything, and it loses the sale of many sets.”
The company suggested that customers warm the pot gradually as to prevent breakage. Maybe a bit of milk might protect their product from the sudden ravages of hot water.
This flaw plagued the new British industry well into the early 1800s as consumers continued to prefer Chinese imports, not so much for design, but for their dependability.
Nicholas Crisp wrote in the Public Advertiser in 1753: “The Porcelain Ware of China is free from Imperfections, and is on this Account become of such general Use, that it must be considered as a great Acquisition to this Nation, could a domestic Manufacture be introduced, that might supply the place of this foreign Commodity.”
Germany had succeeded in making red stoneware pottery in 1707, and by 1710, they mastered the secret of making true porcelain like the Chinese and the Meissen factory was born.