Furnace, Build 2 2024

Using the New Furnace at Winterfest Demo 2024

Last year I had a go at making a couple of furnaces. They worked well, and I learnt a lot, but there were a number of improvements needed. Last year's furnaces can be found here: Furnaces 2023 References can also be found at that link for the information mentioned here. 

My goal when making these was not to use modern materials in the construction of the furnace. I also wanted a furnace which could be worked by a single person. It also needed to be portable, so that I could bring it pre fired to an event without having to wait a week or longer at the event itself. 

I took it to Cold War 2023. The furnace met all these goals, though it broke when transporting home. I believe this was due to it getting wet at the event, and due to the composition used. The composition used was as follows; Slightly decomposed Horse Poo, Clay, Sand. I think I was too hasty and that the horse poo needed to decompose more. The idea is that the beadmaker would go and build their furnace near the river, using the materials there. The furnace would last a little while, but it was not a permanent build. The materials would have ample time to decompose though, so I decided to wait a year and try again with the same composition. 

I think it produced a material that was far more binding, as the fibres had split more and were able to blend and knit together far more effectively. However I am also certain it was a bit caustic, and would urge caution and the use of gloves in handling the blend. 

Much more broken down

More fibres

The original shape I used was modelled after the Ribe furnace. It was tall which allowed air flow to stoke the coals. I did not need a bellows to have the heat required to melt glass. The funnel allowed the heat to be centered at the top of the furnace which was a good point to melt glass, however I found that the best heat concentration was about 20 centimeters below the opening of the furnace. The shape of this furnace allowed me to use the survival fire method, which already primes the wood to have a good balance of air flow, producing high heat. It is not easy to move however, and whilst cracking is normal, the fault lines for this shape effectively cut it in half. You could fix this by making the walls twice as solid, but it would no longer be portable. 

Making the walls more solid

Building the shape up gradually

I spoke to Master Sui before building a new furnace, with similar goals to the first. He provided some insights into why and how it is possible to create a furnace without the use of bellows, and spoke about his experience and best results with certain shapes of furnaces. He also suggested not filling the chamber full of fuel, but rather have it half in to allow better air flow, and higher temps. 

I used this information, combined with last year's research to make a shape that was logical, likely to be used and effective. Amusingly, as I took the furnace to a demo for Winterfest 2024 , most folk called it a pizza oven, which it sort of does resemble. 

Annealling dishes on both sides

I also added rod rests, though rods were not as popular as tesserae in period. 

Due in part to the composition of the furnaces, there are not many extant examples. However we do see examples through history and recent history of low tech furnaces based on knowledge and ways passed down the generations. 

I used this to adapt my furnace slightly and add parts to anneal the beads. The process of allowing the glass to cool down slowly is important, and prevents the glass from shattering. There are a number of historical ways of doing this, having a clay pot near the fire being a common example. 

As I was working on the shape of this furnace, I decided to build in the annealing dishes to the top of the furnace. It worked very effectively, being hot enough to help transistion the glass slowly, but not too hot or too cold. 

The composition of the furnace, with waiting a year, and mixing the fibres a lot better, worked amazingly. I used river clay which I'm pretty sure made a difference as well. 

The furnace was portable. It fired up well. However, despite having the furnace going all day, I didn't get constant functioning heat at the tempertatures I needed. I think the fuel source had a small part to play in this, but I also think it was simply too small. 

Next time I will make it bigger, though I think it may no longer be portable at that stage. 

I will also try another idea, which is to place it on a built fire, and have it act as a funnel. I think this may be quite effective, especially in trying to achieve a pre made furnace, with the flexibility of being able to travel to events. 

Watch this space for that experiment. 

Annealing: https://mo-sci.com/glass-101-glass-annealing/ 

Annealing: https://www.sciencedirect.com/science/article/abs/pii/S0379073811000107 

Glassworking processes & properties [videorecording] / Corning Museum of Glass. Corning, N.Y.: Corning Museum of Glass, 2007. 1 videodisc ( min.) 

This educational video archive presents more than 40 short segments on the various techniques employed by glassworkers: including annealing. Commercially distributed.

Classes 2024

                             Classes with Contessa Ginevra Lucia Di Namoraza 

Rowany Newcomers: Introduction to Glass bead making

9/3/24 

Saturday 3-5 PM 

An introduction to glass beads through cultures and ages, including a practical section to make several of your own glass beads. 

Pre-booking required 

Please bring gardening gloves if you have them. 

Rowany Festival: Introduction to Glass bead making- Workshop 1 and 2

19/4/24

Friday 3-5 pm 

An introduction to glass beads through cultures and ages, including a practical section to make several of your own glass beads. 

Pre-booking required 

$10 fee for materials. 

Please bring gardening gloves if you have them. 

Coronation- Southron Gaard: Introduction to Glass bead making- Workshop 

5/5/24

Sunday 9-10 AM

An introduction to glass beads through cultures and ages, including a practical section to make several of your own glass beads. 

Visiting Mordenvale and Stormhold soon

Visiting Mordenvale and Stormhold soon. 

Private Tuition and sessions by arrangement.

Class Notes

https://gydahrafnsdottir.blogspot.com/2022/05/class-notes-2022-making-glass-beads.html

Researching and recreating Glass Beads through the ages 

An in-depth review and round table discussion of extant artifacts and advanced research and recreation techniques. This hour-long class will take participants through a variety of techniques and approaches to researching glass beads, recreating extant artifacts, creating your own interpretations, and providing detailed documentation. There will also be an overview of how to meet Lochac arts and sciences rubrics and using rubrics throughout the known world to improve your work and research. Books and other documentation will be available for participants to browse.

Historical Pink Glass

                                                        The 4th-century Lycurgus Cup, a 4th-century Roman glass cage cup made of a dichroic glass

I had a project to complete and the brief for the project was "Historical Glass Beads, "Valentine's Day" theme. My immediate thoughts were "pink" and "love hearts". Neither of these have much evidence across the pre 16th century world, so I decided on "red" and "white", and a couple of love heart shapes on the beads on the premise that feathering and odd shapes do ocasionally turn up. 

I thought I might collate any evidence of pink glass here. Any questions or additional sources, please feel free to add. 

Wikipedia: Cranberry Glass

https://en.wikipedia.org/wiki/Cranberry_glass 

The origins of cranberry glass making are unknown, but many historians believe a form of this glass was first made in the late Roman Empire. This is evidenced by the British Museum's collection Lycurgus Cup, a 4th-century Roman glass cage cup made of a dichroic glass, which shows a different colour depending on whether light is passing through it or reflecting from it; red (gold salts) when lit from behind and green (silver salts) when lit from in front.^[2][3] Kitab al-Asrar, an Arabic work attributed to Abu Bakr al-Razi contains one of the earliest modern descriptions of the preparation of gold ruby glass.^[4][5]

Rock Tumblers and Glass Beads

 

So for a while now, whilst studying extant museum glass pieces and recreating them, some things haven’t sat quite right.

The shape and the style can be recreated almost perfectly ( warts and all) but the historical glass look and feel is almost clay like. Almost to the point where sometimes it doesn’t look like glass at all.

This is generally explained by weathering and different glass composition and manufacturing tools and furnaces.

But knowing something and seeing it in action are two very different things.

My sibling got us a rock tumbler for Christmas. The tumbler mimics the ocean or natural wear and tear over centuries.

0.03 seconds after setting the tumbler on, I had to see what would happen if I stuck some glass beads in there.

So I grabbed a bunch of broken glass, and some random examples that I had previously made and popped them in there with the other rocks that were tumbling away.

Some of the glass ( mostly any of the clear glass) came out as gorgeous sea glass style. But the opaque glass and the Phoenician/ Chinese ones came out EXACTLY like the worn thousand year old clay like glass which was freaking cool to see. They’ve only been in there for 4 days or so, so I’ve chucked them back in to see how it continues to tumble. And it feels so smooth and rounded.

I was asked some interesting follow up questions. Tom asked if I thought the orginal beads were tumbled or equivalent in period or if this was just replicating the act of aging?

I answered with the following:

"I haven’t seen evidence to say it was done initially and on purpose, nor any equipment that says it would have been possible. Based on this I would hesitate to say they were tumbled on purpose.

I have seen evidence where some necklaces were found with hundreds of years of age variations on the one necklace, and wear and tear on beads in ways that suggested constant rubbing and deterioration over time caused by potentially one lifetime.

I would definitely say that this effectively replicates ageing over time based on the very similar look and feel, not only on a surface level but looking more carefully at the details of the deterioration of softer colours ( such as the white)"

Any other questions, please ask :)