wombat1138: (narbat)
From Google Books PCR of Stanislav Libenský, Jaroslava Brychtová: a 40-year collaboration in glass by Stanislav Libenský, Jaroslava Brychtová, Susanne K. Frantz, and Thomas S. Buechner, p. 51 ff(?):

The intensity and color offered by glass through its changing density were key attractions for Libensky and Brychtova during the 1950s and 1960s, and most of the pieces from their earliest collaboration through the Montreal monuments used the richest values available. "Safirin" glass, from the Czech word for sapphire, now assumed a prominent position in their smaller-scale sculpture (p.153). This glass, developed for the Jablonec nad Nisou jewelry industry, is dichroic in that the color changes dramatically between transmitted and reflected light. With light bouncing off the surface, the glass appears to be a milky caramel. As light penetrates, first through the thinly ground edges, the glass takes on deepening shades of blue. The color of the glass can range from orange tones to fuchsia, depending on slight differences in the batch and on the heating and cooling schedules of the casting.


(I'm not sure what the p. 153 ref points to inside the book.)
wombat1138: (Default)
Mostly working notes as I try to hash out the whole COE thing.Read more... )
wombat1138: (Default)
copper colloids: Astralite and porpora )

Faberge "purpurin(e)": appears to be a dichroic aventurescent glass, ranging from tawny orange to indigo depending on angle of reflected light; appears to be opaque?

gold colloids )

beads

May. 26th, 2010 12:15 pm
wombat1138: (narbat)
clickable for description:
wombat1138: (narbat)

The key chromophore responsible for the fluorescence is allegedly cadmium sulfide. Since finding this goblet, I've found a few Czech glass beads that seem to be made of the same stuff, but so far I haven't spotted any obvious pointers from my previous attempts to data-mine the Czech glassmakers' color-coding system wrt uranium glass-- and even in the strand that I found at Global Beads down in Mountain View, there are several distinctly different levels of fluorescence brightness despite all of the beads looking identical under normal viewing conditions. I suppose that's not too surprising, considering the difference just between the inside (middle image, UV light from top) and outside (rightmost image, UV light near bottom) of the goblet.
wombat1138: (narbat)
From a 1922 chemistry textbook, emphasis added:
Ruby glass owes its red color to the presence of colloid gold. I show you three specimens which are "solid solutions" of gold in three very different and characteristic degrees of dispersion (demonstration).[1] The first is an almost clear and but slightly yellow mass of glass. This is obtained immediately after dissolving the solid gold salt in the glass. There is obtained in this way a molecularly dispersed solution of the gold in the glass, and one which, in consequence, is ultramicroscopically empty. The second preparation is the ordinary ruby glass in which the gold is contained in a colloid state. The third specimen is deep blue by transmitted light and orange brown by reflected light. The specimen is also distinctly turbid. It springs from a failure in glass manufacture in that, presumably through a too long heating of the glass, a coagulation of the red gold particles to the more coarsely dispersed blue particles has taken place — just such a change as I showed you in an aqueous dispersion medium when I coagulated the red gold (produced through reduction of gold chlorid by tannin) to blue gold through the addition of acid. These same facts as illustrated in the case of glass prove of what little importance is the kind of dispersion medium and how much depends upon the degree of dispersion in determining the variations in color in this substance.

[1]: Different specimens of gold ruby glass were kindly placed at my disposal by POPPER AND SONS of New York


No illos, alas, but "Popper and Sons" still appears to be in operation; I wonder if they'd have any records/samples of what they sent to this guy?
wombat1138: (narbat)
The Lycurgus Cup (dating to Imperial Rome) reflects green but transmits red. Technical analysis here, ascribing the effect to colloidal nanoparticles of gold and silver; there's also a lovely picture of an experimental piece from the Corning glassworks that reflects translucent jade-green but transmits a gorgeous true violet (less red than the standard manganese-based purple).
wombat1138: (narbat)
While (still) looking for info about "orange manganese" glass, found an intriguing late 19th-C reference to a type of glass called "astralite" that I've never heard of before. It sounds beautiful, though: "resembling aventurin [i.e., goldstone], but containing crystals of a cuprous compound, which by reflected light exhibits a dichroitic iridescence of dark red and greenish-blue." The recipe starts with a base mixture combining (in relative proportion) silica (80), lead oxide (120), carbonate of soda (72), and anhydrous borax (18) with a secondary mixture of either "scale oxide of copper" (24) and "scale oxide of iron" (1); or of lime (5), "scale oxide of copper" (26), and "scale oxide of iron" (2). (I may have to look up the equivalent modern terminology later.)Read more... )

weird glass

Oct. 1st, 2008 11:31 am
wombat1138: (spot)
While looking for an explanation of "orange manganese" glass, finally found what looks like a technical explanation of "saphiret glass" in a late 19th-century glassmakers' manual. here: in a way, it's the gold-based analogue to the confusingly named copper-based "goldstone". Both are the result of reducing the chromophore ions in the glass melt: in the case of copper, the metal precipitates out into visible crystals; in the case of gold (usually added at a much lower proportion), the precipitate forms a translucent colloidal haze that (as the source says) reflects light as pale brown but transmits it as sapphire-blue. Read more... )

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