France has always been the center of glass making, even at the close of the dark ages when all the countries in the world were beginning to pull out of the depression of Religious Chaos. Glass making in France, even superseded the making of glass in Italy and the low countries, where industry began first.
It was not the complicated effort or perhaps it was more complicated than our methods today. There was no way invented whereby the impurities could he taken from glass. This accounts for the grand amounts of colored or stained glass windows in the middle ages. It was an attempt to cover up the bubbles, unmelted stones, and foreign metallics in the glass batch.
Experimenting in the glass making techniques, and working with wood and coal fired glass furnace was a painstaking work. It was almost a century after the glass was first made in countries on a commercial basis before pure formulas were worked out for a specific color.
Almost all glass had a bluish-green appearance, or a smoky appearance, depending on the chemicals or the metals present in the sand and silica being used in the making of the glass. There seemed no apparent way to remove the impurities from the sand, but as the nations advanced in knowledge and techniques, it was bound to happen that someone would invent a method of removing most of the foreign matter.
Blue, black and green were the first and easiest glasses to make. This was from the cobalt, nickel or tin in small amounts in the glass batch, common sand, which had these ingredients in it. - At the beginning of the 18th century. it was possible to separate the impurities from the different materials, find silica which was much finer, and in cases where sand was available in the larger glass making centers, the ingredients were of finer quality.
England was the first to isolate nickel a as a coloring agent for almost pure black glass. Of course, all the other ingredients were used for black glass, but larger amounts of nickel were put in to assure as pure black as possible. Because black is a combination of all colors, when transilluminated, black shows purple or a dark ruby. And no matter how thick the piece, if it can be transilluminated, it shows color.
After the nickel agent was isolated, it seemed the whole world was off making black glass. It was something of a status symbol to be able to produce black glass. It didn't take on the name of "Black Milk Glass" until its making began in America at the beginning of the 19th century. And that was a misnomer. Who ever heard of black milk, or blue milk for that matter? It was made' in every county in England, Europe and America. And it never achieved a popularity which other glass enjoyed.
After its move to America, the ingenuity of Americans devised ways of removing iron, tin, and the metallics which gave glass a poor color. By running a magnetized belt over `the sand, the impurities could be removed from the sand. This method has not changed except to become mechanized by electricity or power driven belts.
Black was associated with death. Widows wore black clothing for at least a year. And all members of a family were encased in black from head to toe. Therefore the black glass which had some appearances of the black silk and satin of the period, was not a happy reminder of the pangs of grief.
Little of the black glass was marked. For that matter little glass of any sort was ever marked. One just must learn the history, patterns, and composition of the different firms to distinguish one from another.
Almost all glass houses made the black stuff in one form or another. Some of them went so far as to hand paint brilliant flowers to enhance the beauty of an otherwise dark color. And some engraved and set in, mounting of silver, platinum, and in some cases gold.
Regardless of what they did with it, it was still unpopular. When Prince Albert, the consort to Queen Victoria died, she required her entire court to wear mourning clothes for more than thirty years.
To capitalize on the soft silk veils of the Victorian period, Hydroflouric acid was introduced as a method of softening the glare of black glass. It, when exposed to the fumes of the acid, or was dipped, took on a soft appearance, which seemed to reflect small portions. But it hád the feel, and touch of the satin material.
Satin glass was famous in the Mt. Washington, Thomas Webb. Mt. Joye, and other firms seeking to enhance their colored glasses. And black satin was an instant hit because of its softened color and lovely feel. It had the touch of soft velvet. And more and more people made, sold to the general buying public, and enjoyed prosperity because of the satinized glass.
Not until the late 19th century, and early 20th century did every glass making house turn to making satinized glass. Black was the primary object. But green, pink, ruby, blue, and other colors in the spectrum caught the satin bug.
It has been reported, through the wonderfully illustrated book of colored glass, that Tiffin Glass Co., Tiffin, Ohio made the black satin glass. Of course, when something appears in print, and there are those who take everything at face value, it is assumed that that particular firm made a certain form or style of glass, to the exclusion of all others.
Because it was shown as Tiffin, almost all satinized glass with one layer is called Tiffin. It is a researched and known fact that Tiffin made only the large rose bowls with poppies and chrysanthemums. Every firm in operation, both at home and abroad satinized their glass to get in on the band wagon. Westmoreland, Fostoria, McKee, Heisey, many firms attached to the United States and National glass conglomerates made satinized glass. And Cambridge Glass, the firm from Cambridge, Ohio, in business from 1901 to 1958, sandblasted some of its glass for the soft appearance.
The formula was and is the same for black glass. It contains sand, silica, feldspar, fluorspar and nickel along with arsenic, and lime for purity of color. But then most of the glasses, except opaques, contain this formula. The extra coloring agent is an added attraction. Black glass is accepted as a part of the beauty in glass making.