wg48temp9
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Posts: 761
Registered: 30-12-2018
Location: not so United Kingdom
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Leaded glass in light bulbs
I have examined the glass to metal seals and evacuation tubes of various light bulb. I have also worked the glass in a reducing flame but neither my
working or the manufacturer has left the metallic gray black discoloration typical of leaded soda glass.
I suspected the glass does not contain significant amounts of lead. So I checked. Apparently the Europe Union banned leaded glass in light bulbs in
2011. See Attachment: leaded-glass-S1878029612006184.htm (80kB)
This file has been downloaded 261 times
That's good news if you are in Europe and you want to work old fluorescent tubes with the cheap torches that have reducing flames. The bad news is
the higher softening temperature requires a hotter flame.
On a different point from that paper "Leaded fluorescent lamp glass can also be divided into three types according to PbO concentration as
light red lead, medium red lead, heavy red lead, which is 11%, 20%, and above 28% PbO respectively" No wounder it goes black in a reducing flame.
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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Clear_horizons_glass
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Location: Pullman, WA
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So in your experience lead glass require a much more oxidizing flame to not develop the dark discoloration?
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wg48temp9
National Hazard
Posts: 761
Registered: 30-12-2018
Location: not so United Kingdom
Member Is Offline
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My experience is that a reducing flame reduces the lead in glass to lead metal. I would assume a neutral or an oxidising flame would not reduce the
lead to metal. I can not confirm that by my direct experience because I have never worked glass containing lead with a neutral or oxidising flame.
Though I have read that that is the case.
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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