A chance discovery by French chemists led to the development of a fully toneable “White Acid”. Subsequent tones being produced by exposure to dilute acid. “French Embossing” is generally used to describe the more ornate decorative styles of etching, but technically any process that requires the use of white acid is in fact French Embossing.
Prior to this discovery,the method of turning soda glass opaque was “Blanc fix” or “Chinese White”. This was actually a method of polishing Lead Crystal glassware after it had been cut, but had the opposite corrosive effect on everyday soda glass.