p. 10ff: chapter “The Zenith of Color Glass in the Late Biedermeier Period”; on red stone
glass: s. Busson, Biedermeier Stone Glasses, 1991, p. 20ff.).
Red beads, buckles and other “quincailleries” (glass notions) were always populär in the
Gablonz bijouterie industry. “Gamet colored” and “rose red cut beads” were shown by Zen
ker/Josephsthal in Prague in 1829 (Neuwirth, Color in Glass I, 1993, p. 11), deep dark red
glass fragments were made by Blaschka & Comp as “raw glass composition” (Neuwirth,
Color in Glass 1,1993, p. 33, ill. 12), and the Ferdiand Unger Company in Liebenau, had nu-
merous red samples of its “Ohrbirndeln” (ear pendants). Some hundred years later, Art
Deco necklaces show the possibilities for light and dark, transparent and opaque red col
ored glass used in cut, moulded and wound beads, rocailles and bugles (pp. 18, 42). Sewn
on to the sample cards of Gebr. Redlhammer, are red or red marbled beads in many differ
ent shades (some labled “oriental beads,” some termed “cornelian beads”; garnet and coral
colored versions predominate (Neuwirth, Beads from Gablonz, 1994, pp. 24, 25, 290, 294,
311). Two color charts give an idea of the unbelievable variety of shades of red in rocailles
and bugles (Neuwirth, Beads from Gablonz, 1994, pp. 52, 53).
FORMULAS, PRIVILEGES AND PATENTS
We have innumerable Contemporary formulas for red glass and they are given here in
chronological order (s. 141 ff.). A few Privileges are also listed: in 1881 the Josef Riedel
Company, Polaun, had its “Improvement in the Production of Ruby Glass” registered as a
privilege (Privileges Catalogue 1896, No. 10011, p. 807, Priv. No. G. 32/802, Grant:
27.4.1882, Priority: 8.10.1881). The formula for this ruby glass (200 parts sand, 100 parts
soda, 40 parts sand, 15 parts cherry wood and 7 parts antimonium vitrum) is, however, ap-
parently incorrect since amounts for sand are listed twice.
Riedel also had a “Process for the Production of Solid Pink Glass” patented (Privileges Cat
alogue 1896, No. 10017, p. 808, Priv. No. G 46/856, Grant: 7.3.1896, Priority 6.5.1895):
“In order to produce solid pink glass which already has the red color directly from the pot,
the same has to be colored, and these characteristics are achieved in the following way.
The discovery consists in supporting the coloration of the gold in the batch with phosphoric
acid or with phosphoric acid and aluminium.
The phosphoric acid can be used as such or in the form of salts, such as potassium phos-
phate, sodium phosphate, calcium, phosphate, lead phosphate, stannic phosphate, zinc
Phosphate, that is, in all those salts which do not give the glass color. The aluminum can be
added as powdered metal or in its salts, oxides or minerals in the form of Sulfate, acetate,
silicate, nitrate, and also as aluminum Chloride and aluminum fluoride, etc.
Forsuccess, it is necessary for, depending on the characteristics of thecrystalline batch, as
much phosphoric acid and aluminum to be added as the batch allows without causing
cloudiness or Saturation, or a possible occurrence of Saturation that disappears with re-
heating.”
COLORING GLASS WITH SELENIIUM
In addition to copper and gold, selenium was also used to give glass a red color. Schubarth
already saw “the chameleon-like changes of color” with gold as analogous to selenium
(s. p. 188). Already in 1865 J. Pelouze reported on his experiments in coloring glass with
selenium (s. p. 192).
Towards the end of the 19th Century, a number of Companies were interested in applying for
a privilege to get exclusive rights to color glass with selenium. Some of the Privileges pre-
served in the Austrian Patent Office are listed here in chronological order and in the original
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