What does late 19th Asian Cloisonne Metalworks and European Ceramic Pieces Share? German Glass Chemistry

1. Hand crafted Victorian era decorative cloisonne and hand painted ceramics were both prepared by using a glass flux for their colored enamel hand applied decorations, and then a kiln was used to fire and melt the flux onto the vessel.
2. Both types of decorative wares were part of the huge import export business that flourished between 1850 and 1950 all over the world.
3. Both fabrications improved the quality of their goods, by the changes based on the German advanced chemistry involving glass based compounds mixed with other elements to produce reliable and economical colors with an improved enamel process.

My four images are composed of two before 1879 items, and two after 1879 hand painted enamel on ceramic stoneware, and Asian cloisonne enamel on metal . The claim I am making is documented in two reference books I own. I need to tack down the exact paragraph with the names of the German chemists involved with the date and the locations.

1) Pre 1879: Petrus Regout was born in 1801 and lived until 1888. The Art Nouveau painted stoneware basket set in an ornate metal holder is signed on the base P. REGOUT MAASTRICHT pre 1879 in an oval mark. (my piece). Their initial decorations of the white wares produced were hand painted simple borders and flower styles. Then a massive number were decorated with transfers meant for exports, these would have The Sphinx mark.
2) Post 1879: A German salt glazed platter, with an application of blue enamel, contrasting with the white stoneware base and it's many motifs. Circa 1900. (item image used with permission)

1) Pre 1879: cloisonne plate, decorated with the limited enamel available at the time, with a standard cloiosnne approach in Japan, the cloisonne was fired in a kiln many times to fill the partitions of the design. The result was quite fragile and was easily affected by the wear of time, showing erosion and discoloration. (my item)
2) Post 1879 Japanese cloisonne, with smooth glossy surfaces, the pieces remain in very good condition over long period of time, it also allowed for the innovation of wireless cloisonne, where the wires were removed before the piece was completed and fired again. The group of pieces are mine, they are early to mid 20th century Chinese and Japanese cloisonne items.

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From WIKI:
Vitreous enamel, also called porcelain enamel, is a material made by fusing powdered glass to a substrate by firing, usually between 750 and 850 °C (1,380 and 1,560 °F). The powder melts, flows, and then hardens to a smooth, durable vitreous coating. The word comes from the Latin vitreum, meaning "glassy".
Enamel can be used on metal, glass, ceramics, stone, or any material that will withstand the fusing temperature. In technical terms fired enamelware is an integrated layered composite of glass and another material (or more glass). The term "enamel" is most often restricted to work on metal, which is the subject of this article. Enameled glass is also called "painted", and overglaze decoration to pottery is often called enamelg. Enamel was first applied commercially to sheet iron and steel in Austria and Germany in about 1850.
The word enamel comes from the Old High German word smelzan (to smelt) via the Old French esmail,[2] or from a Latin word smaltum,