This is all great stuff, Bill. I'm sure we're all looking forward to your
piece in Historical Archaeology, especially those of us who work on early
20th century sites.
I'd worry a little about your modern chemist being surprised that selenium
caused glass to solarize to amber back in the early twentieth century. Like
you observe, he probably wasn't familiar with the combinations with other
chemicals, or with the long-term effects of sunlight on the glass. But it
is an interesting observation, nonetheless. I've personally ignored the
"straw-colored" glass talk among the collectors, largely because I couldn't
figure out what they were talking about and couldn't find much of it in my
assemblages anyway.
All of this helps with my saloon report. Thank you!
Cathy
Catherine Holder Spude ¨ Archeologist ¨ Cultural Resources Management ¨
National Park Service – Intermountain Region ¨ 505.988.6831Voice ¨
505.988.6876 Fax
The National Park Service cares for special places saved by the American
people so that all may experience our heritage.
LOCKHART BILL
<[log in to unmask] To: [log in to unmask]
MSU.EDU> cc: (bcc: Cathy Spude/SANTAFE/NPS)
Sent by: Subject: Re: manganese clarified glass date
HISTORICAL
ARCHAEOLOGY
<[log in to unmask]
>
09/22/2004 05:05
PM MST
Please respond to
HISTORICAL
ARCHAEOLOGY
{ SEQ CHAPTER \h \r 1}I hope to do a follow-up article on selenium and
arsenic as decolorants. The
earliest reference I have found for selenium as a decolorant in the US is
1895.
Selenium is still used as a decolorant in the US. It is not the culprit
for the
solarized amber glass (often called “straw-colored glass” in collectors’
literature). I have two chemistry articles that show through experiments
that
more than one chemical combination can create the effect, but key
ingredient
is arsenic – not selenium. When I spoke to a chemist at a bottle
manufacturer
about nine years ago, he was completely surprised at the idea that selenium
would affect glass color.
As to time, the collectors are probably correct, although on report stated
that a
bottle from (if my memory is correct) about the 1950s was solarized amber.
I
can’t completely support this yet, but the use of selenium and arsenic in
combination was used by some companies, apparently in response to the
wartime pressure and the change from mouth-blown to machine production,
beginning about 1915 or so. By about 1930, most had caught on the color
change (or found better formulae – don’t know which yet), and the “straw-
colored-glass” era was generally over.
Bill
> Selenium was used as a clalrifying agent AFTER the supplies of
> Manganese ran out. On top of that, not everybody used it. On top of
> that, those that did did so for varying lengths of time. It creates
> another kind of solorized glass - Amber. This was discarded in the
> depression era since it was cheaper to color glass than clarify it.
>
> Time to offer a rare opinion: There is a special place in perdition
> for whoever came up with that "Lima Beans through a Baby" green color
> so popular in the depression.
>
> :-(
>
>
> Smoke (Michael A.) Pfeiffer, RPA
> Ozark-St. Francis National Forests
> 605 West Main Street
> Russellville, Arkansas 72801
> (479) 968-2354 Ext. 233
> e-mail: [log in to unmask]
>
> It is easier to get forgiveness than permission.
>
>
>
>
> Carl Barna
> <[log in to unmask]
> ov> To
> Sent by: [log in to unmask]
> HISTORICAL cc
> ARCHAEOLOGY
> <[log in to unmask]
> Subject > Re: manganese clarified
> glass date
>
>
> 09/22/2004 02:51
> PM
>
>
> Please respond to
> HISTORICAL
> ARCHAEOLOGY
> <[log in to unmask]
> >
>
>
>
>
>
>
> I thought the purple color was caused by Selenium, the supply of which
> was cut off by WW I.
>
> Carl "Slow Digger' Barna
> Regional Historian
> BLM Colorado State Office
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