Glass 101: Making Fluorescent Glass with Rare Earth Oxides

 

Glass 101: Making Fluorescent Glass with Rare Earth Oxides

Posted Krista Grayson on Nov 20, 2019

What are rare earth elements?

The rare earth elements (REE) are a set of seventeen chemical elements, consisting of the fifteen lanthanides, scandium, and yttrium. Rare earth elements are generally very reactive with oxygen in the ambient atmosphere, and readily form compounds known as rare earth oxides (REO). These oxides are thermally stable, and they are usually the final product when fired in the presence of oxygen. The final stoichiometry is closely dependent upon the temperatures and the oxygen pressure in the ambient atmosphere.

Rare earth elements are called such due to their even distribution over the Earth, making it hard to find a large amount in one location. Scandium and yttrium are included in the REE’s due to their original discovery alongside the lanthanides and also share similar chemical characteristics. REEs are widely distributed geographically, with the key ores mined in India, Brazil, and Malaysia; but they are chiefly mined, concentrated, and separated in China. Semi-fabrication also takes place in China, making it important to world production on several levels.

Applications of rare earth elements

Rare earth elements have been used for a long time in established industries such as catalysts, glassmaking, lighting, and metallurgy, which combined account for 59% of the total worldwide consumption. They are also being used in newer, high-growth areas such as battery alloys, ceramics, and permanent magnets, which account for the other 41%.

Rare earth elements in glass production

Rare earth oxides have been studied for a long time in the field of glass production, specifically how the addition of these compounds may change the properties of the glass. This started in the 1800s when a German scientist named Drossbach patented and manufactured a mixture of rare earth oxides for decolorizing glass. This was the first commercial use of cerium, albeit in a crude form with other rare earth oxides. In 1912, Crookes of England found cerium excellent for ultraviolet absorption without giving color, making it useful for protective eyeglasses.

The most widely used REEs in glass are erbium, ytterbium, and neodymium. Erbium-doped silica fiber is extensively used in optical communication; ytterbium-doped silica fiber is used in engineering materials processing, and neodymium-doped is applied in glass lasers used for inertial confinement fusion. One of the most important uses of REO in glass is the ability to change the fluorescent properties of the glass.

Fluorescent properties from rare earth oxides

Fluorescence in glass has many applications from medical imaging and biomedical research, to testing media, tracing and art glass enamels. Fluorescent glass is unique in that it can appear ordinary under visible light and then can emit vivid colors when excited by certain wavelengths.

Using REOs directly incorporated into the glass matrix during melting allows the fluorescence to persist, where other glass materials that only have a fluorescent coating often fail.

The fluorescence in optical glass, usually silica, is a result of introducing rare earth ions into the structure during manufacturing. When these active ions are directly excited by an incoming energy source, the REE’s electrons are raised to an excited state. The excited state returns to the ground state by emission of light of longer wavelength and lower energy.

This is particularly useful in industrial processes, where inorganic glass microspheres can be inserted into a batch to identify the manufacturer and lot number for many types of products. The microspheres do not interfere with the transport of the product, but when an ultraviolet light is shone on the batch, a particular color of light is produced, allowing precise provenance of the material to be determined. This can be achieved with all sorts of materials including powders, plastics, papers, and liquids.

It may seem that relying on only color for identification may lead to confusion between batch numbers, but the number of parameters that can be altered provides enormous variety in the microspheres. Along with the precise ratio of various REO, other parameters include particle size, particle size distribution, chemical composition, fluorescent properties, color, magnetic properties, and radioactivity.

Producing fluorescent microspheres from glass is also advantageous. Glass microspheres can be doped to varying degrees with REO’s, withstand high temperatures, high stresses, and are chemically inert. They are superior in all of these areas to polymers, allowing them to be used in much lower concentrations in the products.

One potential limitation is the relatively low solubility of REO in silica glass. This can lead to the formation of rare earth clusters, especially if the doping concentration is higher than the equilibrium solubility, and requires special action to suppress the formation of clusters.

Fluorescent glass from Mo-Sci

For keeping track of batches and processes, Mo-Sci offers fluorescent glasses in a variety of colors and excitation and emission wavelengths in sizes ranging from approximately 10 µm to 600 µm. Visit our online store or contact us to discuss your specific requirements.

References

1. Haxel, Gordon B., et al. Rare Earth Elements—Critical Resources for High Technology. USGS, https://pubs.usgs.gov/fs/2002/fs087-02/fs087-02.pdf. Accessed 17 June 2019.[RDM4]
2. Wells, Willard H., and Vickie L. Wells. “The Lanthanides, Rare Earth Elements.” Patty’s Toxicology, American Cancer Society, 2012, pp. 817–40. Wiley Online Library, doi:10.1002/0471435139.tox043.pub2.[RDM5]
3. Elements, R. The Rare-Earth Elements — Vital to Modern Technologies and Lifestyles. (2004) https://pubs.usgs.gov/fs/2014/3078/pdf/fs2014-3078.pdf
4. Strauss, M. L., & Strauss, M. (n.d.). THE RECOVERY OF RARE EARTH OXIDES FROM WASTE FLUORESCENT LAMPS https://mountainscholar.org/bitstream/handle/11124/170305/Strauss_mines_0052N_11053.pdf?sequence=1 
5. Jordens, A., Cheng, Y. P., & Waters, K. E. (2013). A review of the beneficiation of rare earth element bearing minerals. Minerals Engineering, 41, 97–114. https://doi.org/10.1016/j.mineng.2012.10.017 
6. Report, S. I. (2011). Rare Earth Elements — End Use and Recyclability Scientific Investigations Report 2011 – 5094. https://pubs.usgs.gov/sir/2011/5094/ 
7. Adachi, G., & Imanaka, N. (1998). The Binary Rare Earth Oxides, 2665(94). https://pubs.acs.org/doi/abs/10.1021/cr940055h
8. Riker, L. W., Optical, S., & Incorporated, G. (1981). The Use of Rare Earths in Glass Compositions, 81–94. https://pubs.acs.org/doi/pdfplus/10.1021/bk-1981-0164.ch004
9. Vasconcelos, H. C.  and Pinto, A. S. (2017)Fluorescence Properties of Rare-Earth-Doped Sol-Gel Glasses https://www.intechopen.com/books/recent-applications-in-sol-gel-synthesis/fluorescence-properties-of-rare-earth-doped-sol-gel-glasses 
10. Mo-Sci.com Fluorescent Glass Microspheres https://mo-sci.com/en/products/glass-microspheres/fluorescent-glass-microspheres 

Displays for Small Tables

Frequently small or busy craft fairs provide a relatively a small space or table to display your glass.  This means you need to make an impact with little area in which to do it.

There is also guidance elsewhere, but these are some basic ideas to get you started thinking about how to use the space you have and make your presentation stand out.

credit: CountryHeartandHome

Make your display like a shop window display

Think about how a shop with small windows works to display things to attract your attention.  Use your stand to display a single theme or style (sometimes called a brand).  Present your key pieces in a complementary but muted background.  Co-ordinate colour, or shape, or function.  Do not put everything out at once.  Give each of your glass pieces space.  Keep extra stock behind or under the table to meet the need for different colours, sizes or shapes.  Give your pieces space to be appreciated individually. The more unity you can give to your display, the more chance you will get the attention your glass deserves.

Be imaginative in your use of display materials

Think about props you have around the studio or in your home that can complement your glass.  Look for things that fit your style of work, or the theme you are presenting.  It is the unusual, but complementary coverings and props that can help you stand out from the other displays.

Height provides interest and space

You might consider a self-supporting stand that can be placed on the table and provide shelves for your glass – as long as they are stable.  You can drape appropriately sized boxes that you brought the stock in to give height to the display.  If the boxes are appropriate, you can use them bare as platforms or shelves, depending on the arrangement.  Always think about ways to build higher, but secure, displays for your glass.  After all glass looks best with light coming through rather than flat on a table.

credit: dizziebhooked.wordpress.com

Make your display fit the glass you make

Think about what is needed to show your glass off to its best.  Mostly this will be vertical with light filtering through.  Vertical light behind or in front of the glass is good.  This is to avoid dazzling the visitor rather than displaying the glass.  It may be that jewellery is best flat, although earrings can be stunning with light behind.  You can consider constructing something that does not need a table.  Look for inspiration at the kinds of displays used by retailers to save space.

credit: pinterest

Create the illusion of space

Use light colours for table coverings and display materials.  It gives a sense of space, that black does not. Using the same colour throughout gives a sense of unity in the display.

Tablecloths are most often used because they are easy to transport, but they are not the only portable material to use.  You could consider rolls of paper, foam board, and other materials to give a clean minimalist base for the display.

What more could be done with that space behind?
credit: MacrameUK

Space behind your stall

Often there is a backing to the stall.  Make use of it if it is there.  You need to determine in advance from the organisers what backing there is to the stall you will be allocated.  If there is a wall or other partition, make sure you leave it as you found it.  You can also think about providing your own stall backing with the organiser’s permission.   Using the back of the stall increases the space you have to display your glass.

There are many ways to utilise small spaces at craft fairs. Your imagination will be the only limit.  Think of shop displays, build up, give your glass space, ensure good lighting, use the back of your space.

Glass 101: Glass Formers – The Backbone of Glass

 

Glass 101: Glass Formers – The Backbone of Glass

Posted Krista Grayson on Oct 15, 2019

Glass is a state of matter that exists separately from the conventional forms of metal, polymers, and ceramics. There is a wide and varied number of applications for glass that each require a different set of properties. Glass properties are controlled by the composition. One of the most fundamental changes that can be made to the composition is the basic unit of the glass: the network former. The former can be thought of as the backbone of the glass, and changing this element or compound will fundamentally change the properties of the final material.

How are formers used in glass production?

Glass formers are added to the bulk material to facilitate the formation of a glass and form the interconnected backbone of the glass network. The first paper to discuss these components was written in 1932 by Zachariasen, which is considered a landmark in glass research.1 In this paper, he outlines his theories on glass and classifies the three types of cation that glass networks are composed of: network formers, network modifiers, and intermediates. 

Some common cations that are in network formers are boron, silicon, germanium, and phosphorus. They have a high valence state (meaning they have a surplus or deficit of electrons allowing them to bond easily with other atoms) and will covalently bond with oxygen. Network ions that alter the glass network and intermediates are added to gain special properties in the glass.

Applications of glass formers

Various glass formers are used in varying ratios with modifiers and intermediates to produce a glass that can withstand the rigors of a specific application. For example, a glass suitable for handling high-temperature liquids will be made of a different composition than one that is being used for decorative purposes. 

Silicate glass

Silicate glass is one of the earliest types of glasses and is still produced worldwide today. It is formed of Si4+ ions that are covalently bonded to four oxygen atoms, to form SiO4 in tetrahedral shapes.2 They then connect to other tetrahedra by bridging oxygen ions. If each of the tetrahedra is joined corner to corner, it forms the SiO2 polymorph cristobalite that has significant long-range order. This long-range order produces a highly connected network which leads to a high softening point, a low diffusion coefficient, and a small coefficient of thermal expansion (CTE).

If the silica is worked at lower temperatures, it possesses only short-range order. Intermediates, such as sodium ions, can then be introduced to the silica glass to form alkali silicate glass. This is done through the addition of Na+ ions, each one of which creates one non-bridging oxygen. This reduces the network connectivity, resulting in decreased viscosity, and an increased diffusion coefficient and CTE. There is also increased ionic conductivity and reduced chemical resistance.

Boron oxide glasses

When boron oxide is used as the former, the glass is known as borate glass. In this case, the structure is composed of corner-sharing BO3 triangles connected by bridging oxygen. Borate glass can also be made into an alkali form through the addition of Na+ ions. 

However, in contrast to silicate alkali glasses, the initial addition of these alkali ions has the inverse effect on borate glasses. It causes an increase in network connectivity, a reduction in the CTE and an enhancement in thermal and chemical resistance.3 Alkali borosilicate glass is also known as Pyrex® glass; the improved physical properties make it useful for lab equipment and piping, as well as the tiled coating on the space shuttle.

Phosphate glass

Phosphate glasses are based on P2O5, with CaO and Na2O as modifiers.4 Initially these glasses were used for industrial applications such as clay processing and pigment manufacturing, but more recently they have been put to more specialised uses. Research has found that the constituent ions of phosphate glass are similar to those present in the organic mineral phase of bone.5 This chemical affinity to bone sees these glasses being developed for biomedical use, as the inert nature of the glass is ideal for deployment within the body.

Mo-Sci glasses

Mo-Sci has extensive experience in developing and manufacturing glass produced from various types of formers.6 We offer a number of standard glass compositions such as soda-lime silicate, barium titanate, and type 1A borosilicate, as well as being able to develop custom glass compositions for specific applications. Contact us for more information.

References

1. Zachariasen, W. H. The atomic arrangement in glass. J. Am. Chem. Soc. 54, 3841–3851 (1932). https://pubs.acs.org/doi/pdf/10.1021/ja01349a006
2. Hosford, W. F. & Hosford, W. F. Amorphous Materials. Mater. Sci. 153–167 (2009). https://ocw.mit.edu/courses/materials-science-and-engineering/3-071-amorphous-materials-fall-2015/lecture-notes/MIT3_071F15_Lecture2.pdf
3. Yuntian Zhu. MSE200 Lecture19(CH.11.6,11.8)Ceramics. 19, 1–21 https://people.engr.ncsu.edu/ytzhu/Class-Teaching/MSE200/Lecture19-Nov23.pdf
4. Richard K. Brow. Review: the structure of simple phosphate glasses. J. Non. Cryst. Solids 263–264, 1–28 (2000). https://www.sciencedirect.com/science/article/pii/S0022309399006201
5. Rahaman, M. N. Bioactive ceramics and glasses for tissue engineering. Tissue Engineering Using Ceramics and Polymers: Second Edition (2014). https://www.sciencedirect.com/science/article/pii/B978085709712550003X
6. Mo-Sci Glass Products https://mo-sci.com/en/products

Annealing Previously Fired Items

“Double the annealing soak time for each firing” and “Slow the rate of advance each time you fire” are common responses as a diagnosis when a piece breaks in the slumping process.  It may come from the fact that once fired, It is now a single piece that needs a slower rate of advance on the second firing.  I’m not sure where the idea of doubling the annealing process originates.

You need to think about why you would slow the rate of advance and double the anneal for each subsequent firing of the piece.  This is an investigation of the proposals.

Thickness determines ramp rates and annealing

Annealing soak lengths and cooling rates are related to thickness and complexity.  If no additions or complications are added between the previous and the current firing, there is no reason to extend the soak or decrease the rate of cooling.

You of course, need to consider what lay-up and process you are using in the additional firing.  Have you added any complexity to the piece in the previous or the current firing?  If so, you do need to consider how those changes will affect the firing requirements.

Fire polishing

The question to be asked is, “if the piece was properly annealed in the first firing and shows no significant stress, why do I need to change the firing?”

The answer is, “you only need to slow the heat up because it is a single piece now.”  You do need to know that the existing stress is minimal, of course. A note on stress testing is here.  If there is little or no stress from the previous firing, the annealing and cooling can be the same as the previous firing.  Nothing has changed. You are only softening the surface to a shine.  The anneal was adequate on the first firing, and it will be on the second.

If you are firing a pot or screen melt, you have added a complexity into the firing. This is because of the high temperatures used in the first firing.  It means you may wish to be more cautious about a re-firing to eliminate bubbles, or for a fire polish for the surface.

Frit layers

If you are adding confetti or thin layers of frit or powder you have not significantly changed the piece.  You can re-fire the piece as though you are fire polishing any other piece of the same dimensions.

Additional layers

If you are adding more full layers in subsequent firings, you need to reduce the rate of advance to top temperature.  You also need to extend the soak and reduce the cooling rate according to the new thickness of the piece.  This is because the piece is thicker, so the rate of advance needs to be slower, the time required to adequately anneal is longer, and the cooling rate needs to be slower.  All of these changes in scheduling are to accommodate the additional thickness.

Tack fusing additional pieces

If you are tack fusing pieces to the top of an already fired piece, you need to go slower than you would by just adding a full layer.  Tack fusing pieces to an existing piece adds a significant complication to the firing.  Tack fusing requires a firing for thickness between 1.5 and 2.5 times the actual total height of the piece.  The complexity added is the shading of the base glass from the heat radiating from the elements. 

For example, if your piece from the melt is 9mm/0.375", it would have been annealed with a 90 minutes soak. The first cool would be at 69C/127F per hour, and the second at 125C/225F per hour with the cool to room temperature at 415C/750F. If it shows no significant stress, you can fire polish and anneal in the same way as your initial firing.

But

If you tack fuse pieces on top, then you need to treat the piece as though it were between 15mm/0.625" (a little over 1.5 the thickness) and 25mm/1.0" (a little over 2.5 times) thick.  This would require a soak of 3 or 4 hours.  A cooling rate of between 40C/72F and 15C/27F per hour for the first cooling stage is needed. The second stage between will need a rate between 72C/130F and 27C/49F per hour. The final cooling to room temperature will be between 90C/162F and 240C/432F to room temperature.

Conclusion

If you have made no significant changes in thickness or complexity, the second firing can be the same annealing as the first firing. If you have altered the thickness or complexity of the piece, the second firing will need to be slower.

Further information is available in the ebook Low Temperature Kiln Forming.

Glass 101: Using Glass Modifiers to Change Glass Characteristics

 

Glass 101: Using Glass Modifiers to Change Glass Characteristics

Posted Krista Grayson on Sep 16, 2019

Glass modifiers such as lithium oxide, calcium oxide, and zinc oxide can be used to fine-tune the properties of silicate and borate glass to suit a number of niche engineering applications. In this article we take a look at the ways in which common glass modifiers are used to create high-specification glasses for various applications.

Ordinary glass is a unique material. It’s heat-resistant, exhibiting low thermal expansion and excellent thermal shock resistance; chemically durable; exhibits high electrical resistivity; and of course, is highly optically transparent. These properties have made glass an indispensable material in architecture, labware, electronics, and engineering.

Glass can be further transformed into a true wonder-material through the use of glass modifiers. Just like other materials such as steel, the properties of glass can be precisely tuned and augmented through the careful addition of chemical modifiers to suit a huge array of demanding applications.

Glass structure and composition

The constituents of glass can be broadly divided into three categories: network formers, modifiers, and intermediates.1 Network formers form a highly cross-linked network of chemical bonds and constitute the bulk of the glass. Silicon oxide is the most common network-forming constituent of glass, but glasses based on other oxides such as boron and germanium are also commonly produced.

Modifiers are chemicals that can be added to glass in small quantities to further alter the properties of a glass. These include lithium, sodium, potassium, and calcium; which exist as charged single atoms (ions) amongst the cross-linked network formers, reducing the relative number of strong bonds in the glass and lowering the melting point and viscosity. 

Intermediates; which include titanium, aluminum, and zinc; are chemicals that can behave as network-formers or modifiers depending on the glass composition.2 Glasses are naturally highly disordered, and require a carefully tuned balance of network formers, intermediates, and modifiers to prevent the formation of ordered crystallites within the material.

Effects of glass modifiers

As glass generally acts like a solution, the properties of modified glass can be approximately described by additivity relationships: that is, each ingredient contributes to the bulk properties of the glass by an amount roughly proportional to its concentration.3

Glass modifiers interrupt the normal bonding between glass-forming elements and oxygen by loosely bonding with the oxygen atoms. This creates “non-bridging oxygens,” and lowers the relative amount of strong bonding within the glass. As a result, glass modifiers generally have significant effects on glass properties. 

These include a reduction in melting point, surface tension, and viscosity due to weaker overall bonding within the material. These are some of the primary reasons for using glass modifiers – they make glass easier to work with at lower temperatures without affecting transparency.4 Glass modifiers affect the coefficient of thermal expansion, chemical durability, and the refractive index.

Glass modifiers for high-specification applications

Despite a number of common properties, the unique chemical properties of different glass modifiers can have varying effects on the properties of the glass produced. 

Chemical Durability

The use of alkali metals such as sodium and potassium as modifiers generally reduce the chemical durability of glass, whereas alkaline earth metals such as calcium can increase the chemical durability of glass.5

Resistivity

In electronics, the high resistivity and permittivity of glass lend it to applications in resistors and capacitors. The addition of tellurium, germanium or titanium oxides to glasses in low concentrations have been shown to drastically increase resistivity, making them popular as glass modifiers for ultra-high resistance applications such as hearing aids and infrared detectors.6

Glass for labware

Glass with strong chemical durability and resistance to thermal shock is highly valued in labware manufacturing. The addition of zinc oxide to silicate glass can reduce thermal expansion effects, making it especially resistant to thermal shock. Borosilicate glasses, which use borate as well as silicate as a network former, are also especially thermally resistant and chemically durable, making them a popular choice of material for reaction vessels, test tubes, and other labware.

Specialty optical properties

Some glasses are prized for unusual optical characteristics: zinc-modified glass is widely used in photochromic lenses, while silver, gold, and copper can produce photosensitive glass which changes color in response to incident light.4,7

Bioactive glass

Of particular interest to the biomedical community, bioactive glass is a form of modified glass that closely emulates the properties of the mineral portion of living bone. Bioactive glass is highly biocompatible and forms strong chemical bonds with bone. 

This material consists of around 45% silicate with calcium and sodium acting as the primary modifiers. This results in a comparatively soft glass which can be readily machined into implants for use in the repair of bone injuries.8

Mo-Sci leading precision glass technology

Mo-Sci is a world-leader in precision glass technology and produces a range of high-specification glasses for application in healthcare, electronics, and engineering. With expertise including bioactive glass, high refractive index glass, and fluorescent glass; Mo-Sci is able to produce custom solutions for virtually any glass application. Contact us today with your specifications!

References

1. Karmakar, B., Rademann, K. & Stepanov, A. L. Glass nanocomposites: synthesis, properties, and applications.
2. Kienzler, B. Radionuclide source term for HLW glass, spent nuclear fuel, and compacted hulls and end pieces (CSD-C waste). (KIT Scientific Publishing, 2012).
3. Industrial glass | Britannica.com. Available at: https://www.britannica.com/topic/glass-properties-composition-and-industrial-production-234890#ref608298. (Accessed: 17th May 2019)
4. Phillips, G. C. A Concise Introduction to Ceramics. (Springer Netherlands, 1991). doi:10.1007/978-94-011-6973-8
5. Hu, J. MIT 3.071 Amorphous Materials 2: Classes of Amorphous Materials. https://ocw.mit.edu/courses/materials-science-and-engineering/3-071-amorphous-materials-fall-2015/lecture-notes/MIT3_071F15_Lecture2.pdf
6. Weißmann, R. & Chong, W. Glasses for High-Resistivity Thick-Film Resistors. Adv. Eng. Mater. 2, 359–362 (2000).
7. Photosensitive glass. (1948). https://patents.google.com/patent/US2515275
8. Rahaman, M. N. et al. Bioactive glass in tissue engineering. Acta Biomater. 7, 2355–2373 (2011).

Craft Fair Checklist

www.madeurban.com

There are so many things you need to remember before starting off to the event you have signed up for.  A checklist can help reassure you have everything you need and are prepared for your visitors and customers.

Spread the word

Let everyone know about the fair – your acceptance, your preparations, what you are taking, what else is happening at the event, etc.  The more stall holders talking about the event, the wider the publicity will be, and it should attract more visitors.

Set up at home

Set out the floor space you will have and see how you can make your stand be the best.  Mock-ups at home allow trials of various displays.  Set up one day and leave it for the next.  Your immediate impression the next morning will tell you if it is right.  When you have the display right, photograph it so you have a reference at the setup at the show.

Design your own banner

Most big organisers will have a generic name board for your stand.  Everyone has that.  Your pitch can stand out if you have designed a banner which reflects your glass work and business logo.  It needs to be boldly visible and state the business name clearly.

Tool kit 

You need to have a box or bag of all the things you need to set up and sustain you for the event.  There are the things you need to operate during the show - a float of cash, pens, business cards, Publicity material, blu-tac, scissors, string, strong tape, wet wipes, polishing cloths, pens, phone charger, and a small notebook, tablecloth, price labels, bags, packaging,  a card reader, smart phone or internet connected tablet, directions to the venue, etc.  Your list will vary to some extent for your needs, but will be much the same for large and small events.

You need to think about yourself too.  Bring bottles of water, snacks, chewing gum or mints, tissues, a folding chair, anything else you need for sustenance for 6- to 10- hour days;  and a positive attitude.

Make it possible to carry all of it

Remember you have your set-up materials – stands, boxes, supports, and survival bag.  You also have to get your glass and packaging into the premises too.  How are you going to manage? Will a folding trolley be needed? Maybe some other carrying method will be better.  Pack things up and practice transporting them for a distance.  If it is too heavy, try other methods such as breaking the materials into smaller units.

Have your directions to the event with you

You need to be sure how to get to the venue to avoid any panics.  Make sure you have plenty of time to get to the place.  Being early allows you to have a rest and calm down after setting up and before the visitors enter.  Give yourself plenty of time to unload and park the car – everyone else is trying to do the same thing as you and at the same time.

Pricing 

Make your price list days before the fair, ideally as soon as you have finalised what glass you are taking.  Make sure all the glass is clearly priced, so the less confident buyers don’t have to ask. If you are selling online, the prices should be the same. You may want to offer discounted prices at the event, but the ticket price should be the same as online.

Business details

Bring business cards to hand out to people who cannot make the decision to buy on the day.  They may decide to buy later. A discount code written onto the card may stimulate a later purchase from the online shop.  Have publicity material available too – something about you, your glass, and your business.  Price lists are useful if you meet buyers and wholesalers.

Card reader

A method to take card payments is essential. A sign or logo indicating that you take card payments encourages people to purchase.  If you don’t already have one, give yourself enough time to get it, as it often takes at least a month.  And you have to get familiar with it before the show.

Web presence

Make sure that your website, your shop and your social media are up to date.  Events often cause more traffic to your sites, so they need to be ready before you leave for the event.  This means hiding anything that is one-off or difficult to replicate.  Sometime after the show they can re-appear.

Conversations

Be ready for the people you will be meeting with a variety of starters for the conversation with different visitors.  You will probably have a different conversation with a buyer than with the general run of visitors.  You want a conversation to get feedback on your glass and other things relevant to your glass, display and general presentation.  These also help discover what may fit the people who want to buy, or comment on your work in ways that can help you improve or even start new glass lines.  Have a notebook to record the feedback you get as soon as you can at the event.

Plan friendly, but not pushy conversation openers.  You can offer help in describing the qualities of your glass, rather than how it was made.  Be prepared to talk about yourself, your inspirations, how you work, etc.  Be interested in the visitors – their likes, desires, what they are looking from the event. 

It is from these conversations that you can expand your mailing list.  The people you have pleasant conversations with will be willing to join your mailing list and the social media you participate in.  Enjoy your event!

Engage with your neighbours 

If you are on your own for a long day, you will need help from them to cover for your toilet breaks at the least.  Friends you make at shows can become long-term and can be a source of information when you have questions.  They don’t have to be glass workers.  It is a good way to business network and get mutual support.

Based on an article written by Camilla from Folksy blog.folksy.com

Glass 101: Glass Processing Temperatures

 

Glass 101: Glass Processing Temperatures

Posted Rebecca Molt on Aug 14, 2019

Glass is an amorphous solid with no long-range order. This lack of order is what differentiates a glass from a crystalline solid. For example, when silicon dioxide is cooled slowly through the crystallization temperature, it is allowed to form crystals, giving the solid a geometric structure throughout the material. When silicon dioxide is heated and then rapidly cooled, it’s ordered crystalline structure is unable to reform and it becomes an amorphous solid (glass). [1] 

Glass goes through different transitions during melting. The glass transition temperature, softening point, and crystallization temperature are all part of the glass forming process. Careful maneuvering through these steps is critical to the formation of a stress-free glass product.

Glass Transition Temperature

The glass transition temperature (Tg) characterizes a range of temperatures where an amorphous material transitions from a hard brittle state to a viscous state relative to increasing temperature.[2] The solid begins to exhibit viscoelastic properties above Tg. When disordered molecules are below Tg, they have less energy, and the molecules aren’t able to move into new positions when stress is applied. When above Tg, the molecules have more kinetic energy, allowing them to move in order to alleviate applied stresses.[3] The annealing temperature is selected based on the glass transition temperature, allowing any stress to be released before completely cooling the glass.

Littleton Softening Point

The Littleton softening point (Ts) of glass is the temperature at which the glass moves under its own weight. As a glass is heated, the glass flows more easily. The resistance to flow is known as viscosity. At the softening point, the glass has a viscosity of 107.6 poise.[4] This point is often used to define the working range of the glass. Once the glass has reached the softening point, it is malleable without melting.

Crystallization Temperature

The crystallization temperature (Tx) characterizes the onset of crystallization. Crystallization is the process of forming a solid. The molecules become highly organized into a geometric structure known as a crystal. This occurs in two steps. The first step is the nucleation or “seed” formation. Nucleation can be influenced by the initiation of a secondary phase formation within the matrix or the introduction of an outside substance, such as particles from the crucible. The second step is crystal growth, which is the growth around the original nucleation sites in layers.[5] Crystallizing brings the melt down to a lower energy state. If a melt crystallizes it will not become a glass since glass is a disordered solid. Crystallization is avoided by rapidly quenching through the glass transition region. 

Coefficient of Thermal Expansion

The coefficient of thermal expansion (CTE) describes a material’s change in shape, area, and volume in response to temperature change.[6] Heat is a type of kinetic energy. When a material is heated, its kinetic energy increases which causes the molecules to vibrate at a higher frequency. The molecules then take up more space than usual. The reverse is true when cooling a material. When cooled, the molecules have less kinetic energy, and they contract, taking up less space....

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References

1. NDT Resource Center, http://www.ndt-ed.org/EducationResources/CommunityCollege/Materials/Structure/solidstate.htm, Center for NDE, Iowa State University.
2. ISO 11357-2: Plastics – Differential scanning calorimetry – Part 2: Determination of glass transition temperature (1999).
3. The Glass Transition. https://pslc.ws/macrog/tg.htm. Accessed: 21 June 2019.
4. Technical Glasses: Physical and Technical Properties | SCHOTT Technical Brochure. https://www.us.schott.com/d/tubing/ffed51fb-ea4f-47d3-972e-5a2c20f123f5/1.0/schott-brochure-technical-glasses_us.pdf. Accessed: 21 June 2019.
5. Crystallization |Reciprocal Net http://www.reciprocalnet.org/edumodules/crystallization/. Accessed: 24 June 2019.
6. Tipler, Paul A.; Mosca, Gene (2008). Physics for Scientists and Engineers – Volume 1 Mechanics/Oscillations and Waves/Thermodynamics. New York, NY: Worth Publishers. pp. 666–670. ISBN 978-1-4292-0132-2.
7. Novel Sealants to Significantly Improve the Lifetime and Performance of Solid Oxide Fuel Cells | Mo-Sci Blog https://mo-sci.com/novel-sealants-Improve-solid-oxide-fuel-cells. Accessed: 25 June 2019
8. Mo-Sci Corporation Website https://mo-sci.com/en/custom-development. Accessed: 24 June 2019.