I wonder if you ever heard this myth about glass. The myth is that glass is not a solid but a highly viscous liquid, slowly flowing.
Proof given was that old pains of glass are sometimes rippled with this flow. The totally clear pains next to them are recent replacements.
A few years ago I read an article debunking this myth. No, glass is indeed a solid, although it has no crystal structure to it. It does not flow. Those old pains of glass were just badly made. The clear ones next to them are just as old, but better quality.
I realized at that point that we on this forum have been looking at the real debunk of the myth, vacuum tubes. With that high vacuum the glass would be constantly flowing inward. Since flow would be uneven, we would never see vacuum tubes from the 30's with intact vacuum.
Just think how much harder it would be to restore vintage radios if the myth were true.
Best Regards,
Bill Grimm
: I wonder if you ever heard this myth about glass. The myth is that glass is not a solid but a highly viscous liquid, slowly flowing.
: Proof given was that old pains of glass are sometimes rippled with this flow. The totally clear pains next to them are recent replacements.
: A few years ago I read an article debunking this myth. No, glass is indeed a solid, although it has no crystal structure to it. It does not flow. Those old pains of glass were just badly made. The clear ones next to them are just as old, but better quality.
: I realized at that point that we on this forum have been looking at the real debunk of the myth, vacuum tubes. With that high vacuum the glass would be constantly flowing inward. Since flow would be uneven, we would never see vacuum tubes from the 30's with intact vacuum.
: Just think how much harder it would be to restore vintage radios if the myth were true.
:
:Best Regards,
:
:Bill Grimm
What you're talking about is that glass is called an amorphous (sp?) substance, in that it has no melting point, that is when heat is applied it starts getting soft, and than softer, and then eventually it is a liquid, just as some alloys of solder will have a pasty stage they will go through between liquid and solid (cold solder joints, anyone?) By the time that glass gets to room temperature (or tube temperature) it is very much a solid, and a brittle one at that.
Lewis
Never thought of, nor had I heard of that bit about glass supposedly being in an ever
"flowing" state dimensionally wise. I consider it to be as equally stable in sizing as
all other items that we normally have dealing with in our 0-150 degree F temperate ranging
that we would typically have them stored in.
You really threw me on the "pains" bit there, until I reread it again and then zeroed in on
PANES..hi.. hi.
Looks like some variances of glass will melt as low as 500 deg F while the higher quality
and lab grades take on up to 2900 deg F.
If glass didn't have that extended plastic state and gradual transition...woe be the poor
glassblower. Whereas in our soldering operations, there is sometimes advantage in using
the the eutectic grade of Sn63/Pb37 and its almost immediate transition from a melted to
solidified state...plus its lower 361 deg F melting point.
Also, the ripple effect on some of the older first generation of glass making might have been from a technique of
taking a large blob of molten glass and dropping it in the center of a large carbon disc that is then spun up in speed and the glass distributes outwardly and thins down and then
sets up into to a thinner, spread out sheet of glass, then to be trimmed to size.
73's de Edd
::Hi All,
:: I wonder if you ever heard this myth about glass. The myth is that glass is not a solid but a highly viscous liquid, slowly flowing.
:: Proof given was that old pains of glass are sometimes rippled with this flow. The totally clear pains next to them are recent replacements.
:: A few years ago I read an article debunking this myth. No, glass is indeed a solid, although it has no crystal structure to it. It does not flow. Those old pains of glass were just badly made. The clear ones next to them are just as old, but better quality.
:: I realized at that point that we on this forum have been looking at the real debunk of the myth, vacuum tubes. With that high vacuum the glass would be constantly flowing inward. Since flow would be uneven, we would never see vacuum tubes from the 30's with intact vacuum.
:: Just think how much harder it would be to restore vintage radios if the myth were true.
::
::Best Regards,
::
::Bill Grimm
:
:
:
:What you're talking about is that glass is called an amorphous (sp?) substance, in that it has no melting point, that is when heat is applied it starts getting soft, and than softer, and then eventually it is a liquid, just as some alloys of solder will have a pasty stage they will go through between liquid and solid (cold solder joints, anyone?) By the time that glass gets to room temperature (or tube temperature) it is very much a solid, and a brittle one at that.
:Lewis
:
Hi All,
Thank you for the comments. I am pained about my spelling of pane.
When I was a kid and a ham radio operator, I belonged to a club whose members were quite knowledgable about designing things with vacuum tubes. One member had designed a souped up transmitter, which eventually burned the traps out of his triband antenna.
Once he came to a club meeting with one of the tube finals from his beast. Its envelope had been sucked in.
That doesn't happen in radios.
All the Best,
Bill Grimm
I've also seen glass sucked in on tubes. That happens when they get very hot and glass softens. Vacuum will suck in the glass.
I've heard the same about window panes. Seems it would be easy to verify? Glass should sag downward.
Norm
::I know that the ripples in old windows is from how they were made. However, I remember seeing a science show in grade school that talked about 500 year old windows suddenly breaking from becoming too thin at the top. I don't know if that is true, or if maybe sunlight melts them. They talked about a church window breaking, and then showed a leaded glass window shattering (most likely a set-up). Leaded glass windows would never shatter and fall to the ground. They are made up of small pieces of glass, and are held together with lead. However, they do sag, since lead stretches. It is sad seeing some of the magnificent houses which are now part of Milwaukee's ghetto. ....Poorly maintained houses with wonderful leaded glass windows that now sag (or get stolen).
:
:Hi All,
: Thank you for the comments. I am pained about my spelling of pane.
: When I was a kid and a ham radio operator, I belonged to a club whose members were quite knowledgable about designing things with vacuum tubes. One member had designed a souped up transmitter, which eventually burned the traps out of his triband antenna.
: Once he came to a club meeting with one of the tube finals from his beast. Its envelope had been sucked in.
: That doesn't happen in radios.
:
:All the Best,
:
:Bill Grimm
:
: I've also seen glass sucked in on tubes. That happens when they get very hot and glass softens. Vacuum will suck in the glass.
:
: I've heard the same about window panes. Seems it would be easy to verify? Glass should sag downward.
:
:Norm
:
:::I know that the ripples in old windows is from how they were made. However, I remember seeing a science show in grade school that talked about 500 year old windows suddenly breaking from becoming too thin at the top. I don't know if that is true, or if maybe sunlight melts them. They talked about a church window breaking, and then showed a leaded glass window shattering (most likely a set-up). Leaded glass windows would never shatter and fall to the ground. They are made up of small pieces of glass, and are held together with lead. However, they do sag, since lead stretches. It is sad seeing some of the magnificent houses which are now part of Milwaukee's ghetto. ....Poorly maintained houses with wonderful leaded glass windows that now sag (or get stolen).
::
::Hi All,
:: Thank you for the comments. I am pained about my spelling of pane.
:: When I was a kid and a ham radio operator, I belonged to a club whose members were quite knowledgable about designing things with vacuum tubes. One member had designed a souped up transmitter, which eventually burned the traps out of his triband antenna.
:: Once he came to a club meeting with one of the tube finals from his beast. Its envelope had been sucked in.
:: That doesn't happen in radios.
::
::All the Best,
::
::Bill Grimm
Hi all,
I have heard both that glass is a very viscous liquid - the phrase put to me was "a supercooled liquid", and also the story that for this reason, glass "warps" with age, explaining why 50 year old windows look unevenly sagged. I stuck to believing all this official sounding knowledge although some have argued that indeed the glass was just poorly made - but I'll be curious what other responses turn up here.
Eddie
::
:: I've also seen glass sucked in on tubes. That happens when they get very hot and glass softens. Vacuum will suck in the glass.
::
:: I've heard the same about window panes. Seems it would be easy to verify? Glass should sag downward.
::
I've heard the same and the example given was a long glass rod hung on a wall with pegs about 2' apart for support. Allegedly if left that way for a year or so sagging will be noticable between the pegs. Don't know, never tried it. PL
::Norm
::
::::I know that the ripples in old windows is from how they were made. However, I remember seeing a science show in grade school that talked about 500 year old windows suddenly breaking from becoming too thin at the top. I don't know if that is true, or if maybe sunlight melts them. They talked about a church window breaking, and then showed a leaded glass window shattering (most likely a set-up). Leaded glass windows would never shatter and fall to the ground. They are made up of small pieces of glass, and are held together with lead. However, they do sag, since lead stretches. It is sad seeing some of the magnificent houses which are now part of Milwaukee's ghetto. ....Poorly maintained houses with wonderful leaded glass windows that now sag (or get stolen).
:::
:::Hi All,
::: Thank you for the comments. I am pained about my spelling of pane.
::: When I was a kid and a ham radio operator, I belonged to a club whose members were quite knowledgable about designing things with vacuum tubes. One member had designed a souped up transmitter, which eventually burned the traps out of his triband antenna.
::: Once he came to a club meeting with one of the tube finals from his beast. Its envelope had been sucked in.
::: That doesn't happen in radios.
:::
:::All the Best,
:::
:::Bill Grimm
:
:Hi all,
:I have heard both that glass is a very viscous liquid - the phrase put to me was "a supercooled liquid", and also the story that for this reason, glass "warps" with age, explaining why 50 year old windows look unevenly sagged. I stuck to believing all this official sounding knowledge although some have argued that indeed the glass was just poorly made - but I'll be curious what other responses turn up here.
:Eddie
:
: I've also seen glass sucked in on tubes. That happens when they get very hot and glass softens. Vacuum will suck in the glass.
:
: I've heard the same about window panes. Seems it would be easy to verify? Glass should sag downward.
:
:Norm
:
Norm, the surrounding atmospheric pressure outside the tube crushes the glass envelope in when it softens. PL
:::I know that the ripples in old windows is from how they were made. However, I remember seeing a science show in grade school that talked about 500 year old windows suddenly breaking from becoming too thin at the top. I don't know if that is true, or if maybe sunlight melts them. They talked about a church window breaking, and then showed a leaded glass window shattering (most likely a set-up). Leaded glass windows would never shatter and fall to the ground. They are made up of small pieces of glass, and are held together with lead. However, they do sag, since lead stretches. It is sad seeing some of the magnificent houses which are now part of Milwaukee's ghetto. ....Poorly maintained houses with wonderful leaded glass windows that now sag (or get stolen).
::
::Hi All,
:: Thank you for the comments. I am pained about my spelling of pane.
:: When I was a kid and a ham radio operator, I belonged to a club whose members were quite knowledgable about designing things with vacuum tubes. One member had designed a souped up transmitter, which eventually burned the traps out of his triband antenna.
:: Once he came to a club meeting with one of the tube finals from his beast. Its envelope had been sucked in.
:: That doesn't happen in radios.
::
::All the Best,
::
::Bill Grimm