h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I didn't quite get why the glassblower didn't burn their lips if they were using a steel pipe and molten glass. Is this the point of the 'cool the surface' step? Is it really that cool, and still malleable enough to blow into shape?

By the way, this is an awfully fascinating article.

It is only the "glass end" that you make hot. A little bit
like a blacksmith when he is forging.
sio2

The steel, or more often stainless steel, blow pipe does indeed get hot. The glass ranges from one to two thousand degrees when on the pipe, and steel is a conductor of heat.

The blow pipe is about four feet long, though, and only gets hot for about twelve to eighteen inches back from the glass gather. This leaves plenty of room to manipulate the pipe.

Glass is a nearly unique material in that it doesn't melt as such, but is liquid at 2000 degrees and gradually becomes more viscous as it cools to solid form at about 1000 degrees. Thus, after one gathers some glass, one can cool it and shape it and it may well still be malleable enough to continue to blow and shape. The period of time one has to shape it before it is too cool to shape is called "working time", which can vary from glass formula to glass formula.

And actually, if you really want to be technical, glass is also interesting in that it never really does quite go to a solid form - the form that we are used to seeing all over the place is, in fact, simply a liquid that is so viscous that it appears solid. However, the amount of time for glass to flow noticeably to the eye is, by many estimates, longer than the amount of time that humanity has known how to make glass. but it has, nonetheless, been measured with precise equipment.

And steel definitely isn't that good a conductor of heat. i do some blacksmithing (not much) and have often had a piece of iron a foot long with it's end literally white-hot, melting on the surface, and burning, but whose end was still quite cool enough to comfortably hold in my bare hand (steel burns at high temperatures, and makes interesting sparkles. But this makes a pitted surface on whatever you were working on, and destroys utterly any fine details).

And actually, if you really want to be technical, glass is also interesting in that it never really does quite go to a solid form - the form that we are used to seeing all over the place is, in fact, simply a liquid that is so viscous that it appears solid. However, the amount of time for glass to flow noticeably to the eye is, by many estimates, longer than the amount of time that humanity has known how to make glass. but it has, nonetheless, been measured with precise equipment.

And steel definitely isn't that good a conductor of heat. i do some blacksmithing (not much) and have often had a piece of iron a foot long with it's end literally white-hot, melting on the surface, and burning, but whose end was still quite cool enough to comfortably hold in my bare hand (steel burns at high temperatures, and makes interesting sparkles. But this makes a pitted surface on whatever you were working on, and destroys utterly any fine details).

And actually, if you really want to be technical, glass is also interesting in that it never really does quite go to a solid form - the form that we are used to seeing all over the place is, in fact, simply a liquid that is so viscous that it appears solid. However, the amount of time for glass to flow noticeably to the eye is, by many estimates, longer than the amount of time that humanity has known how to make glass. but it has, nonetheless, been measured with precise equipment.

And steel definitely isn't that good a conductor of heat. i do some blacksmithing (not much) and have often had a piece of iron a foot long with it's end literally white-hot, melting on the surface, and burning, but whose end was still quite cool enough to comfortably hold in my bare hand (steel burns at high temperatures, and makes interesting sparkles. But this makes a pitted surface on whatever you were working on, and destroys utterly any fine details). This is probably on a somewhat shorter timescale than when a glassblower is dealing with his/her material on the end of a steel rod, though, so the given measurements sound quite plausible for the length that is actually heated. And one could always put a bit of water on the hot part of the steel, so long as care is taken not to touch the glass with the water and crack it.

And i apologise for the multiple postings, this computer is not mine and is being annoying.

glass is infact a solid at room tempereture and does not flow over long periods of time any more than a piece of wood does( though who knows maybe wood flows slowly over time, its not really my field of expertise).

glass is called an "amorphus solid" ie it has no crystaline structure unlike most other solids. instead it has a random structure like a liquid which is what defines it as a glass. however this does not make it a liquid.

all movement stops at about 500 degrees celcius for normal glass you would find in the home. this is when you need to anneal glass when its being produced becuase once it becomes solid it will crack or explode if not cooled slowly and evenly.


a real example of a liquid appearing solid is pitch which takes decades to move small distances( for more information look up the pitch drop experiment)