Featured Tales from the Crypt, reminiscences of a glass student

Hoping that others will follow,

Many years ago I had an opportunity to discuss glass matters with a glass factory chemist. Among my questions was "Does sugar in a batch of glass turn it amber because it caramelizes?" He chuckled and said "No. before the batch melted the sugar would have all burned up. Sugar is an organic compound. it adds carbon to the batch, interacting with the iron present in almost all glass, turning it to rust. Rust is what gives amber glass it's color."
Many years later, in a visit to the Viking factory in West Virginia, I noticed a batch cart, awaiting an empty pot. Lying on top of it were grains of oats. I asked one of the workers "was that a batch of amber?" He said "Yes, How'd you know?" I pointed to the oats. Old glass workers were fond of relating going out in the street, (19th century) and bringing in a shovel full of horse manure for the amber batches.
And we wonder why there are so many colors of amber.

This is too important to loose, it's never appeared in any books.

 

The Romans were already doing something like this to darken & even out the color of chalcedony, soaking in a sugar solution then subjecting it to high heat. Think, though, in this case, it is the burnt carbon that is the coloring agent, not an interaction with iron. Really interesting - thanks.

 

Wonderful info, thank you both.
Looking forward to more Tales from the Crypt.

 

Faberge created moonstone by immersing agate for days in boiling honey.

 

Tom how about some squibs in "All About Glass"

 

It's probably well-known, but I've heard tales of gold coins tossed into a mix of ruby glass to improve the color.

 

Thanks always learning here.
Manure... oy!

 

This is the sort of knowledge that, when shared like this, makes this forum so rewarding. My interest in glass is negligible, as in my knowledge. But this is the sort of "social archeology" that needs to be shared with those that are more interested in the Why than the What. Thank you for realizing that and for being a part of the community that perpetuates the "backstory" of everyday life.

 

I too am looking forward to many more tales in the future & appreciate it greatly that you would take the time to educate us.

It just enhances my admiration of the artisans who created all of the beautiful glass that I see.

 

Makes you wonder how these things get discovered in the first place.

 

Yeah, this was the story for quite a while. Gold had to be dissolved in "Aqua Regia", a combination of sulfuric and hydrofluoric acid. The added to the batch as a liquid.

At one time, as recently as 150 years ago, these were family secrets passed down from father to son. Really.

 

George, my writer has written her last epic. Her eyes have given out. She was AAG's editor for 9 years.

 

Tom Sorry to hear that. I am fighting a delaying action with AMD myself. So far it is slowing the vision loss down.

 

There seems to be some confusion about opalescence. Its all dependent on what's in the glass. To make glass opalescent, the batch must include some bone ash. Once the piece has its final form, or at least is removed from the mold (swung vases come to mind) the areas that the worker wants to make opalescent is chilled with a blast of cool air. This precipitates something in the in the bone ash to make the glass white. The glass may be reheated to be formed a bit more, swung or ruffled, or what ever. Then it is sent to the lehr to be slowly cooled. Glass that is meant to be opaque (white) is not treated this way, it's got other chemicals in it, usually tin oxide. Any clear colored glass can be made opalescent.