gmshedd

6 hours ago, ThomasPowers said:

Have any of you checked the melting point of copper vs the working temperature of glass?---and remember that structural strength generally plummets as you approach melting temps!

Yes, the melting point of copper is 1984F, and the working temperature of glass at the consistency of honey is about 2130F (that's the temperature they use at the glass shops I'm familiar with). Another reason to switch to iron pipe.

However doing the most general of research: Wikipedia, under Glassblowing, mentions "Researchers at the Toledo Museum of Art attempted to reconstruct the ancient free-blowing technique by using clay blowpipes. The result proved that short clay blowpipes of about 30–60 cm (12–24 in) facilitate free-blowing because they are simple to handle and to manipulate and can be re-used several times." citing:  Stern, E.M. & B. Schlick-Nolte (1994). Early Glass of the Ancient World 1600 BC – AD 50. Ernesto Wolf Collection. Verlag Gerd Hatje: Ostfildern.

The bibliography for that section looks very interesting and citing a number of academic journals in archeology, chemistry,  etc; with the "Journal of Glass Studies" being a heavily cited source.

I bought that book (used) last week for $10, and I looked up E. M. Stern's J Glass article that includes the discussion of clay blowpipes, too. She obviously wasn't convinced that the first glassblowers immediately started using iron blowpipes, but I would like to ask her what she thinks now--her book and journal article are both from about 1993-94. There could have been some new archaeological discoveries in the decades since then.

6 hours ago, ThomasPowers said:

Thanks for the MFA info. I'll check to see what they have.

6 hours ago, jlpservicesinc said:

Again I understand the heat transfer thing.. But please just take a 3 or 4 ft long pipe and heat the end till it's red..  Your hands and or mouth will be fine at the other end.. 

     Being without a pipe, or a fire, I'll take your word for it!  I know that in the glass shops at the museum where I work there are two indicators: 1. They leave one end of the stainless punties (50"+ X ~5/8" solid rod)  in the fire to keep them warm enough to be dipped directly into the 2100F glass. The hot ends are orange when pulled from the fire. Sometimes the gaffers even dip the hot end briefly into water before doing the gather. But the other end is cool enough to be picked up without difficulty, even after sitting there for hours. 2. There are many times when a gaffer has been working with a piece on the end of a stainless blowpipe for long enough (>10-15 minutes) that they will use a pipe-cooler--a water-filled tray about 2 feet long with cutouts at each end for the pipe to drop into, that allows them to submerge the center section of the blowpipe (where they hold it) without affecting the piece on the end.

Where the problem comes in is if you angle the pipe upwards so there is a draft created pulling the hot flame and gases into the pipe..  I actually did a lot of experimenting when I was a child and learned just holding my thumb over the pipes opening was enough to keep the heat or draft from going up the pipe.. 

Luckily for glassblowers, this is seldom a problem because as soon as they gather glass on the end of the blowpipe, that seals the passage so that air doesn't freely flow while they are working with the piece.

I remember the pipe clearly as well as other glass items in the cases.. Mostly stamped or formed..  But then again as with all this stuff my memory is not what it used to be and could have easily gotten information mixed up..  

Our museum has glass artifacts from the time of Akhenaten (about 1335 BC), including one that is a molded glass image of his face. The artifacts we have are pressed, or cast, but none are blown. I have read of copper pipe from an Egyptian tomb of about 2500 BC, but haven't see it in the flesh.

Dates and such used to be very important to me and as I have matured the past occurrence or time frame has become less important as the only time there is,, Is now..   2000 years from now they will be saying the same thing about us and will be wondering why there is such a mix of extinct technology but that forged hinge still works..  

I was never very interested in history myself, but learning about the ancient items in our museum has piqued my curiosity about some of the details of the time in which they were made.

jlpservicesinc, thank you adding to the conversation. I added some comments that may, or may not, be of interest, beneath your comments above. Do you remember the name of museum where the Egyptian items were displayed?

5 hours ago, jlpservicesinc said:

it was the person who they removed from the Egyptian history

It may have been Akhenaten, originally called Amenhotep IV. He became monotheistic and made everyone become so as well. After he died, they reverted to polytheism and eventually erased his name, and that of his son, Tutankhamun (King Tut) from the list of pharaohs. If it was from the era of Akhenaten, then that would be from the last third of 14th century BC, which was about 1300 years before the advent of glass blowing.

The thermal conductivity of copper is more than 6 times higher than that of iron--about 400 W/m-K for copper vs. about 60 W/m-K for iron. Perhaps enough to make a difference.

I think it's possible that someone would have tried copper pipe for glassblowing, but as someone pointed out earlier, a copper pipe would have been a bit uncomfortable to use because of its high thermal conductivity. Do you remember anything about when it was used? 

26 minutes ago, SLAG said:

Wiki professor Girschman. Also, read the latter portion of the cited Wiki article, to the section discussing the said professor's discovery and  his findings.

When I follow the link to the Roman_Ghirshman wikipedia page, I find no mention of glass, although all but one of the cited articles on that page are in French language journals, so I might be missing something. I also find, at the top of that page, just beneath his name, Page issues-This article needs additional citations for verification (December 2009).

When I follow the link to hyperlinked Chogha Zanbil page, the only mention of glass is as "ornaments of faïence and glass." All of Ghirshman's articles referenced on this page are in French, except a 1961 Scientific American article.

When I reread the Glassblowing wikipedia page, the only text regarding Ghirshman's finds of glass is that which you originally quoted above, which is supported by two references (18 and 19). 19 is written in Persian, and 18 is in Encyclopaedia Iranica. So there may be two references, one written in Persian, and the other probably written in French, that back up the assertion in the quoted sentence that the glass bottles that Ghirshman found when he excavated a 2nd millennium BC site in Iran in the 1930's constitute conclusive evidence that glassblowing was invented in the 2nd millenium BC. The same Wikipedia article that makes this assertion, then almost immediately contradicts what it just said by also asserting that "The invention of glassblowing coincided with the establishment of the Roman Empire in the 1st century BC." Obviously, both assertions cannot be true. Personally, I hesitate to place much faith in a fact that comes from a self-contradicting Wikipedia article that can only be verified if I can find, and then read, two obscure references that are written in Persian, and, most likely, French, especially when I find no mention of this 2nd millenium BC version of the invention of glassblowing in any other book or article I've read on the history of glass and glassblowing. As I said in a previous comment, I tend to doubt accepted dogma, so maybe Elam was the birthplace of glassblowing, but it will take more than one sentence in a sloppily-written Wikipedia article to convince me.

On 2/15/2018 at 11:39 PM, SLAG said:

Here is one reference.  https://en.wikipedia.org/wiki/Roman_Ghirshman 

I don't find the quote above at the link provided, but I do find it in the Glassblowing page on Wikipedia, under History: Origins (https://en.wikipedia.org/wiki/Glassblowing). Six sentences after the sentence you quote, the section labeled "In the Roman Empire" begins with this sentence: "The invention of glassblowing coincided with the establishment of the Roman Empire in the 1st century BC." It is this later period that is generally accepted in the glass history books as the time when glassblowing was invented. I can certainly understand the confusion based on how the Wikipedia page is written.

9 hours ago, Glenn said:

Please site your reference to the iron blowpipe and the size of the blowpipe.

If you mean by reference, who has said there were iron blowpipes around 1st century AD? Karol Wight in Molten Color: Glassmaking in Antiquity (2011) p. 53, and many other authors, as well. Within glass books it's so commonly repeated, almost word for word, that I began to wonder if everyone was just copying the first person to assert it as fact, without really thinking about it--that's what brought me here. As for the dimensions of the original iron blowpipes, I can't be certain, but current blowpipes are about 3/4" x ~5 feet. The length is a matter of being long enough to be away from the heat. I thought a cruder forged iron pipe would probably have a larger diameter.

More incredible

3 minutes ago, ThomasPowers said:

I know a lot of people who forge meteorite.

More incredible to me than Tut's meteoric blade (other-worldly though it may be) were the hundreds of feet of copper pipe that were (supposedly) found in the tomb of King Sahure, the second King of Egypt's 5th Dynasty, who ruled from 2517 to 2505 B.C.

45 minutes ago, SLAG said:

he is also an engineer and worked the Corning company

Perhaps we crossed paths at Sullivan Park.

15 minutes ago, SLAG said:

The use of smithed iron dates to about 1,100  or 1,200 B.C.E. (by the Hittites).And tempered iron to about 500 or 600 B.C.E.The use of blown glass predates that by more than almost a millennium.

Is there a book or a reference you can point to that has an example of blown glass from ~1500 BCE? The curators at the glass museum where I work would be very interested. The oldest pieces in our museum date to the 15th century BC, but the earliest blown-glass pieces we have are from the first century BC or AD (I'd have to look it up).

25 minutes ago, SLAG said:

Glass making/manipulating using blowpipes was first used 2,000 B.C.(E.).

Although there are quite a few glass artifacts from as long ago as the 15th century BCE, these were made by core-forming, fusing, casting, and mold-pressing. There are also some pieces of unworked-glass that predate 2000 BCE, but no worked objects that I'm aware of. The earliest blown glass artifacts (inflated by blowing through a tube) are widely accepted by glass history scholars to be from the 1st century BCE. They were actually formed by inflating the melted end of a glass tube, by blowing into the other end.

I agree with you that there were probably clay blowpipes in the earliest days of glassblowing, but the advantages of iron pipes are considerable, so when they became available, they would have been preferred. A group of glass-blowers tested the clay pipe hypothesis back in the 1990's and concluded that glassblowing with clay pipes was possible, but that they weren't very strong transverse to the long dimension of the pipe.

Very true. Thank whoever for the iron blowpipe! It may be interesting to those who work iron, that some of the tools a glassblower uses to shape glass are flammable--made of fruitwood (because it's close-grained) and even folded-up newspaper, although in both cases there is a lot of water involved too!

Good point, although I suppose that if there wasn't any such thing as iron, some bright boy might have tried to use some ceramic insulators around the copper pipe, or a ceramic section in the middle, between two sections of copper pipe. However, copper melts below 2000F, so it would be very touchy to use in a glass furnace. Melted glass is commonly kept at 2100F these days to maintain a consistency like honey, although 1st century AD furnaces could have been very different. Modern blowpipes are low conductivity stainless, so they conduct even less heat than iron. Still, glassblowers use pipe coolers (water troughs) if they work on a piece long enough.

2 hours ago, ThomasPowers said:

May I commend to your attention how they made gun barrels just 200 years ago by either lapping or spiraling the wrought iron and forge welding it together.

You are so right! I just finished watching the Colonial Williamsburg video on YouTube when you posted this. Thank you.

2 hours ago, ThomasPowers said:

So the answer to the original question is Yes.  (Unless you are planning to replicate it I might have suggest the question be phrased: could a blacksmith working at the time of Christ forge an iron pipe?)

Yeah, I am a docent there and was doubting what people who specialize in glass had to say about iron blowpipes--that's why I came here, and I got my answer in less than an hour!. The earliest iron blowpipes (found at glassmaking sites in Spain) are from around the 4th century AD, so I was thinking it was a stretch to say that iron blowpipes had been universally adopted for glassblowing within a century of its invention in the mid first century BC. Furthermore, it seemed unlikely that people who already had pipes made out of lead, and, to a lesser extent, copper would bother making pipes out of iron. But now that I've seen the gunsmithing video I am no longer skeptical about whether a first century blacksmith could make a blowpipe.

Thanks to everyone for your replies. I now believe that 1st century AD blowpipes could have been made of iron.

BTW, the estimated iron production at the height of the Roman Empire was almost 83,000 metric tonnes, and they were apparently making iron in Britain in the first century AD (https://www.thehistorypress.co.uk/publication/the-roman-iron-industry-in-britain/9780752478593/)

The Iron Age began about 3000 years ago in the Middle East, so by the time of Christ, iron was well known.

Any tool that wouldn't have existed 2000 years ago.

Dear sirs: I’m hoping not to waste your time, but I would like to know whether you think it would be possible for a blacksmith to make an iron pipe that is about 1 inch outside diameter (any inside diameter bigger than 1/4") and 5 feet long, using no modern tools?   The reason I ask is that glassblowers from the time of Christ are said to have used iron blowpipes.