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Applied Feet & Finials – Pre-made, Or Made In Concert With The Other Parts? Let’s Look At The Undeniable Physics Of It!

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famatta127's loves15 of 1407KAJ FRANCK - FINLAND  "SMALL JUG"Hantich & Co. "Johnolyth" Vase
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    Posted 8 months ago

    (46 items)

    A suggestion in this forum has once again surfaced, presenting the idea that the black feet (or attached feet of any color) on certain types of pieces, along with finials, are possibly made in advance of the other pieces to be applied to production as it occurs.

    I am only posting this so that people are made aware of the physics of glass and glass production, so as to understand the inability for this to be accurate. I discussed it previously when it was claimed, and I find myself having to address the issue again.

    First, let’s look at some basic science:
    Water boils at 212 degrees at sea level.
    Common types of glass are primarily made from silicates. Most glass consists of Sand, Lime and Soda.
    Colors in glass are developed through the addition of certain elements into a molten batch of clear glass.
    Glass, depending on the type, reaches a molten state at a temperature of 1400-1600 degrees F.
    Glass is generally cooled down very slowly in an annealing oven whose temperature is reduced slowly over an extended period of many hours.
    The reason for that type of cooling process is that if allowed to cool quickly, many types of glass will crack due to temperature variances between the surface and the inner core of the glass.

    Most types of common glass crack when at room temperature and are then subjected to an extreme temperature variation quickly.

    Let’s start with the idea of filling a drinking glass with boiling water. Most folks are aware that if you pour hot water into a glass at room temperature, that there is a good chance that the glass will crack, or shatter unless the glass is meant to be subjected to heat, such as in pyrex or corning ware. Knowing this, imagine the reaction between a room temperature item, and a 1400 degree item…

    First, Let’s look at the reason that this occurs.

    If I have a glass that is at room temperature and I fill it quickly with boiling water (212 degrees F) the glass will immediately start to absorb heat from the water. The glass does not all change temperature instantly. What occurs is that the surface of the glass itself will start to heat up and expand (as all materials do when heated), but the interior of the glass does not instantly absorb heat. As a result of this, there becomes a quick disparity between the internal and external temperature of the glass. As the heated surface tries to expand, the inner core of the glass can not move as quickly as it is cooler, and the tension that occurs within the glass itself causes a crack, or in worst case scenarios, it causes it to shatter.

    It is the internal tensions within the glass that occur naturally when cooling or heating glass, that are avoided with the use of an annealing oven in production.

    If one is not careful in production, these cracks can occur to the objects being formed. As an example, it is not uncommon to find small internal cracks at the contacts points on an art glass pitcher with an applied handle. These are referred to as a heat check. Heat checks occur because of the difference in temperature between a molten handle and a slightly cooled pitcher body. The only way to avoid heat checks in production is to make sure that the glass being applied (handles, feet, flowers, rigaree, edge trim et al) is the same temperature as the main body of glass. Heat checks do not occur the instant that a hot handle is applied to a hot pitcher body. They occur as the two parts of the pitcher cool at different rates, and the internal glass tension causes cracks to occur. Sometimes those cracks are very small, and sometimes they can be catastrophic to the item being produced.

    So let’s take a moment and examine the process if we were going to make a foot or a finial (or any other item) in advance of producing vases or other objects, for those pieces to be applied to.

    The first step in the process would be to form the foot or finial in a small mold of the desired shape. Once removed from the mold, the next step would be to cool the items to store for later use. Because of the thickness of this type of item, it would be necessary to cool such an item in an annealing oven to prevent it from cracking as it cools, or to prevent it from being fragile if cooled without annealing it. If an items is cooled without annealing it, then certain types of tensions, or stresses occur naturally within the glass. Those tensions cause the glass to be much more susceptible to breaking from normal use. Those tensions can also be the cause of cracks to appear in glass without any apparent reason, and out of the blue, so to speak.

    So let’s say we made feet and finials, and cooled them to use for later production.

    In order to use such a piece of glass in production, the formed items would require heating up slowly to the temperature of the piece being created. If not heated up slowly, the glass would crack from the inner vs outer tensions cause by the temperature disparity between internal and surface temperatures.

    If not brought up to a temperature range the same as the main vase body being blown, when applied to the 1400 degree molten glass, the premade pieces would shatter from the huge heat disparity between the two objects.

    So in the suggested scenario, one would make the feet and finials, cool them in an annealing oven, reheat them to approx. 1200-1400 degrees F, and then apply them to the pliable glass object being produced.

    So let’s examine what is actually done.

    Art glass production, even to this day, is a task performed by a group of people, otherwise known as gaffers. Each gaffer on a production team performs a different task. One will be the individual who blows the main object. Others may lay frit on a marver table, or use paddles and shears to perform certain aspects of the production, or gather a small amount of glass to be used to create a threaded surface on an object. And the orchestration and timing of these individual parts of the production is critical. If the glass cools down too far, it will be reintroduced to the oven to bring the temperature back up to the necessary working range.

    One of the gaffers on such a team would be in charge of producing the feet at the same time the main vessel was being created. The final, feet, etc would be molded and then applied to the object. With both of them being molten glass, it would ensure that there would be no damage from temperature disparities, and also enable the fit between the pieces could be as good as possible with both items being pliable and molten. The finished objects would then be cooled in an annealing oven for packing and shipping after they were cool.

    The basic physical properties of cold glass and hot glass, combined with all of the additional work (think extra money spent) precludes the premanufacture of parts such as this. The exception to that would be if the feet and finials were glued to the items, which is not the case we see in early Czech production specifically, and in most art glass production in general…. Even today…..

    This is not really an opinion of mine, but reflects the characteristics of glass production, the physical properties of glass itself, and the issues caused by temperature disparities in production pieces.

    So let’s look at a couple of applied feet on Welz production in my collection and see what they can tell us through a close examination.

    Images 1 and 2 show two different pieces of Welz with an applied foot. Although the connection between the two pieces (body and foot) is reasonably smooth to the touch, it can be felt that they are two different pieces of glass.

    The 4th image above shows us the bottom of the two pieces of glass, and there is no indication of pontil work. This tell us that the feet were removed from a mold and punty rod by being cut at the point where the base attaches to the bottom of the vase body.

    The macro shot in the 4th image is one that shows that there is a trail of glass where the base attached to the body of the vase. This type of glass trailing would be an indication that the piece would have been pliable and molten when applied to the bottom of the vase body.

    All things such as rigaree, threading, finials, flowers, feet, were produced at the time that the individual bases were made. I am only posting this because I feel that people looking to understand glass should understand some of the basic properties of the material…. Properties that have a huge impact on how art glass can and can’t be produced.

    Physics are physics, glass is glass, and facts are facts…. No matter how hard one tries to imagine that something different occurs, the materials (combined with an assessment of production costs) dictate how they can and can’t be used in production.

    Edit 2.29.2020
    Additional comments on the post I am addressing, and my responses to them.

    TOD says:
    "My intent here was to share a simple foray into possibilities, I am always curious about potential variations and how they might be handled."

    My response:
    The laws of physics, combined with the physical properties of glass, exclude using annealed production to apply to new molten production. A true understanding of the physical properties of glassand the laws of physics provide insight to the understanding that this is not a real world possibility. The logical question would be if one was to produce, anneal, and then reheat a piece of production to apply it to a freshly produced example, "Why would one go to all the effort to do that, when it is much simpler, quicker, and prudent to simply produce the foot, finial, flower, rigaree et al, at the same time?"

    TOD says:
    "As far as I have seen and know, it it possible to handle a piece annealed glass (cooled off slowly) and add some newly heated glass to it as long as the point of juncture of the two glass objects are at the same temperature."

    My Response:
    In order for a molten and pliable piece of glass to be attached to an annealed piece of glass, it would be necessary for the two pieces to be at the basically same temperature range. (1200-1400 degrees F) It is impossible, due to the physical properties of glass, to heat one area of an annealed piece of glass to that temperature, without also slowly heating the remainder of the piece to the same temperature. If one area of a piece of glass is heated to a high temperature without the surrounding areas being the same temperature, the item will crack or shatter. This is not "my opinion", this is an inarguable result of the laws of physics and expansion as determined by the physical properties of glass itself.

    TOD says:
    "There has very complicated designed glass items, when this was necessary, in the Dale Chiluhy methods."

    My response:
    Having originally come from the Seattle area, I can assure everyone that the use of annealed glass to attach to a newly produced piece of glass has never occurred in Chihuly production. Also having watched glass production at Pilchuck Glass School north of Seattle (Chihuly founded), all production which occurs by these artists is done with newly melted glass batches regardless of how complicated the piece is.

    TOD says:
    "As my critic also seems to be a mind reader, and bases his conclusions on his usual negative perceptions about me when I am the target."

    My response:
    My "target" is not TOD. My "target" is the bad information being suggested as a "possibility" in glass production, when in reality, it is a fanciful production notion which the laws of physics and properties of glass would preclude from being used. My objective, in doing this post, was to help those that are interested, to learn why such a suggestion in infeasible.

    End Edit

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    1. DuDa DuDa, 8 months ago
      Absolutely correct. Physics is physics and there is no escaping it.

      Heat checks are common in older glass handles. The thinner the handle, the higher the chance of it checking. We have a Fenton off hand vase that has a long slender handle down each side of the vase. On this form heat checks are the rule rather than the exception. We searched for several years to find one without the heat checks.

      There are many videos available online that show this process being done.
    2. welzebub, 8 months ago
      Yeah.... but it would seem that one would actually have to want to understand the subject to go watch one... :-) I fear that is not the case here, as I explained this process in this forum before.... and yet the information was treated as "Fake News"... LOL

      This time instead of comments on a post that could be deleted, I felt that a post of my own would at least remain available to those wanting to understand this topic regarding glass production. This explanation can't be deleted.

      Here is a link to the post which I am providing accurate information to counter.
    3. IronLace IronLace, 8 months ago
      Excellent information!
    4. scottvez scottvez, 8 months ago
      Great information!

      Using facts and science to make a case-- doesn't seem to be an accepted method by many today!

    5. welzebub, 8 months ago
      Thanks to all that stopped by and commented or loved the post. I am glad that some found the factual information to be useful.....

      I have always believed the old adage.... "You can lead a horse to water..... but you can't make them drink...." Proven time and again in this forum.....
    6. welzebub, 8 months ago
      In the post above, I have added some responses to additional remarks made by the OP on their post. The remarks I am responding to were added in the comments on the post I am addressing.
    7. LoetzDance LoetzDance, 8 months ago
      DuDa - You are absolutely correct there are many videos that show how molten glass objects are made. Hot glass has been worked into various artistic shapes for hundreds of years. Glass artists have added handles, feet and other embellishments to glass since the beginnings of ancient glass production. It was and is certainly possible today for an artist to add previously annealed pieces of glass to a new molten, work of glass art. The only requirement for the artist is to reheat the earlier made piece(s) to a temperature that will allow it to be worked with and therefore connected to the new, molten piece of glass. I have included a link below to a video that shows how various pieces of a glass dragon (specifically the feet and horns) were made much earlier but worked in later to complete the creation a beautiful red dragon. Enjoy!
    8. welzebub, 8 months ago
      Gee Deb... I think you may have missed the point of the conversation.

      Deb says " I have included a link below to a video that shows how various pieces of a glass dragon (specifically the feet and horns) were made much earlier but worked in later to complete the creation a beautiful red dragon."

      The pieces that you are discussing as made "much earlier", were made as part of the project that was being shown, and were NOT ANNEALED and stored for later use. They actually discuss the time frame it took to make all of the parts including the body and the feet etc.

      As described in the video, They were produced as part of a 4 hour project and then heated with a torch and attached. If you hit a piece of annealed glass with a blowtorch to reheat it, it would shatter. Even sitting there, that glass retains some heat, and does not exhibit the physical properties of COOLED and ANNEALED parts.

      I appreciate the video though, as it kind of proves the point in the question I asked, which is "Why would one make, anneal, store, and then try to reheat a part, when making it as part of the actual production of the object (as done in the video) is clearly a simpler and less risky path to take.

      It is also noteworthy I think that a comparison of an artistic object which takes multiple people 4 hours to make one, is a far cry from the idea that someone is making black feet (or anything for that matter) in advance of making a very simple vase that was likely produced in a matter of minutes from start to finish.

      Thanks for dropping by though, as always it is a real pleasure to hear from you.
    9. LoetzDance LoetzDance, 8 months ago
      Craig, Please watch the video again. In the first minute the narrator tells us that: "Jason made the leg earlier in his own studio back in Seattle. He brought it down to 253 and put it in their pickup oven so he could heat it up and add it to this new bit...."
    10. welzebub, 8 months ago
      I already watched it Deb....

      The legs were were put in a pick up oven to bring them back up to temperature slowly. It is obvious they are hot when he holds them and applies the glass to it. You can see the feet glowing.

      I am pretty clear in my discussion above, that any piece that was cooled would have to be brought back up to temperature before being used. The video demonstrates that clearly. They just don't tell you how long it had to be in that oven before it could be used.

      From my discussion above:

      "In order to use such a piece of glass in production, the formed items would require heating up slowly to the temperature of the piece being created. If not heated up slowly, the glass would crack from the inner vs outer tensions cause by the temperature disparity between internal and surface temperatures.

      If not brought up to a temperature range the same as the main vase body being blown, when applied to the 1400 degree molten glass, the pre-made pieces would shatter from the huge heat disparity between the two objects."

      This video of a Dragon being produced, is a far cry from the concept of making feet for a vase to store and use later. In the case of what was proposed by TOD, it would take longer to reheat a small foot in a pickup oven to use it, than it would to actually just mold it on the spot and apply it to the base of the vase body.

      I did not say it could not be done.... What I stated was that from a practical and cost effective production method, it was impractical and time consuming, which means it is impractical and overly costly compared to other production techniques.

      Pretty Apples and Oranges. But an interesting video supporting my opinion....

      I stand by my contention that feet and finials (et al) were not produced in advance to be reheated and added later. Dragon feet.... That is a different story. :-)
    11. Trey Trey, 8 months ago
      Beautiful colors :)

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