Orientation of Iridised Glass

Iridised Glass – Which Side Up?

“One rule in using iridised glass is iridised down to fuse, up to slump”

You need to understand the conditions for the “rule" before applying it. Bullseye iridescent and Spectrum System 96 (made by the Uroboros method - not the stained glass) iridescent are not temperature sensitive in the way the other fusing ranges are. Both Bullseye and System 96 can be fired face up.  It is not yet (June 2019) known how Oceanside fusing compatible iridescent will perform when it becomes available.

The Wissmach luminescent and the other fusing glasses seem to be more temperature sensitive and so need to be fused iridised side down.  Avoid using Bullseye Thinfire in contact with the iridescence, as it sometimes reacts with the iridescence and creates pits in the glass.

Use the lowest practical temperature when forming with the luminescent face up. This avoids the partial or complete disappearance of the metal film that creates the iridescence.

More information on what causes the iridescence.

http://glasstips.blogspot.com/2019/06/iridescence.html

Slumping unknown glasses

I had a recent request for help from an old friend who has taken up kiln formed glass. The problem is common enough, that (with her permission) I am adding it to the tips section.

I tried an experiment today to use some of my nice (non-fusing) glass. I cut at 270 mm diameter circle from a 3mm thick sheet and wanted to slump it into my 270 mm bowl mold. I set the mold up carefully and checked it was dead level in all directions and that the glass was absolutely centered on it. I have no idea what the COE is so decided just to use the S96 recommended slumping temperature of 650C. When I checked the kiln no more than 2 minutes after it had reached 665C, the glass had slumped almost to the bottom of the mold but it had slumped very asymmetrically. There was also a small burp on one side which has never been an issue when slumping bowls in this mold before.

The schedule I used was as follows:
200C/hour to 540C, 0 hold
650C/hour to 665C, 10 hold
Then standard S96 anneal programme

Also, the edges were still a bit rough from the cutting, i.e., they hadn‘t fire polished at all. Can you help?

Finding out about the softening characteristics of the glass

Slumping a single layer of glass with unknown characteristics – the CoE is not really relevant – requires that you watch it and other similar ones until you have established a slump temperature for the glass.

There is a way to do it:
Cut a piece of glass 305mm long by 20mm wide. Support it 25mm above the kiln shelf with the posts being 290mm apart. Put kiln furniture on top of the glass where it is supported. Make sure you can see the shelf just under the middle of the suspended glass when you are setting up this test. You can put a piece of wire or other dark element there on the floor of the kiln to help you see when the glass touches down.

Set the kiln to fire at 100C/hour to about 680C. Peek at the suspended glass every 5-10 minutes after 560C to see when the glass begins to move. Then watch more frequently. If your kiln has an alert mode on it, you could set it to ring at each 5C increase in temperature, otherwise use an alarm that has a snooze function to make sure you keep looking. When the glass touches down to the witness sitting on the shelf, record the temperature. This will approximate the slumping temperature in a simple ball curve mould.


Getting smooth edges

You need to have smooth edges before slumping. You can fire polish the piece of glass to get rounded edges, or you can cold work the edges with diamond hand pads, working from the roughest to the finest you have available. If that does not give you the edge you want, you will need to fire polish before you try to slump.

You can do at least two things to find the fire polish temperature. You can do a little experiment by using the cut off pieces of the glass and roughing them up a little before putting in the kiln. Make sure you can see it through the peep hole(s). Set the kiln to fire at about 250C to say 750C. Look in from about 700C to determine when the edges begin to round.

The other is to put a strip of the same glass in with the slump test and set the kiln to go up to 750C rather than just 680C. You can check on progress just as for the separate firing to determine the fire polish temperature. I think about 40C above slump temperature should be enough, but your test will determine that.


Avoiding uneven slumps

Most uneven slumps occur because of too fast a rate of increase in temperature. The piece can hang up on the mould sometimes causing the glass elsewhere to slide down to compensate. The real difficulty in the schedule was the 650C/hour rate up to the top temperature. This was so fast that the glass at the edges would have the opportunity to soften and so hang before the centre was soft enough to begin to bend. 150C / hour would be fast enough from 540C to achieve the slump.  In fact, 150C/hour all the way to the slumping temperature would be fast enough.  The glass reacts well to a steady input of heat rather than rapid rises, even with soaks at intervals on the way up.

Other things can be done too. You mentioned the edges were rough from the cutting. This can cause difficulties of hanging. To avoid that, you should smooth the edges before placing the glass on the mould. A further precaution against uneven slumping is to give a slight bevel to the bottom edge so that it can slip more easily along the mould.

You had already done the leveling of the mould and the centralization of the glass on the mould. These are two other things that can cause uneven slumps.


Avoiding “burps”

The glass slipping a long way down the mould is often accompanied with burps or bubble like up-wellings. These are both indications of too high a temperature being used to slump. I would begin looking at the glass from about 600C in the slumping of any unknown piece of glass. That would apply to any new configuration of the glass or mould too. The fact that the glass slid to the bottom and had a burp means that the temperature was too high and too fast. Once you have established the lowest slumping temperature, by watching to see when it begins, you then can add about 30 minutes soak to that temperature. The length of this soak will have to be determined by observation and experience, though.

A slow heating allows the glass to be at an even temperature throughout its thickness. A rapid rise with a thick piece will sometimes reveal a tear like opening on the underside of the glass that does not come through to the top. This is because the upper surface is sufficiently hot to begin slumping while the bottom is just a little too cool. If there is too great a difference, the glass just breaks all the way through.

Also slow heating allows the slump to be accomplished at a lower temperature, leading to fewer problems and to less texture being taken up from the mould.

More detailed information is available in the e-book: Low Temperature Kilnforming.

Sand Beds for Kilns

Sand beds can be used for shaping directly into the sand or as a bed for a large kiln to avoid having to place a number of shelves together and patch cracks. It also saves on the purchase of a large shelf, at the expense of some labour before each firing.

Mix (by weight)The mix is largely sand with powders to coat the sand particles to reduce the amount of sticking to glass. The mix ranges from 75% sand 25% alumina hydrate, up to 67% sand, 33% alumina. The proportions can be adjusted by experience.

Some kiln formers include plaster or china clay (kaolin) in various proportions so the whole mix can range from 70% sand, 25% alumina, 5% plaster/kaolin up to 60% sand, 20% each alumina and plaster/kaolin. Some have found that the plaster started to scum up the glass after a number of firings, and this can happen with china clay too.

UseThe use of sand as the bed of the kiln requires screeding of the sand before each firing. It is possible to smooth the sand with a plaster’s float. This presses the sand down and allows a fine film of powder to coat the surface. A more certain way of avoiding the sand sticking to or texturing the glass is to lay fibre paper over the sand.

You should be aware that a sand bed requires a little different cooling than glass on a suspended shelf does. Effectively you are cooling the glass on the bed of the kiln. Thus, you should use annealing and cooling schedules for one or two thicknesses more than is actually being fired to be really safe.

Sand formingIf you are using the sand for mild shaping, sprinkle alumina hydrate over formed sand to reduce sand particle take up and textures onto the glass.

Renew sand regularly if you are using powders on the sand. An annual renewal using half the old sand mix and the rest new will be sufficient in most cases. The effect of too much powder is to promote large bubbles as air cannot move through the sand with the same ease as when there is less powder. An easy way to tell if you have too much powder is that the mix flows ahead as you screed it.

Revised 22/6/19

Manipulating Slumping Glass in the Kiln

In my view the protection you need at slumping - or combing - temperatures are:

Face and hair protection – a face shield with a coating to reduce the infrared glow is ideal, but expensive.

Good heat protecting gloves – do not cut corners here. You need something more than leather or welders’ gloves.

Heat reflecting sleeves – the aluminised ones work very well.

A reversed denim jacket to protect your chest - you don't want hot buttons!

A helper to hold the lid/door open.

The tools

Wet timbers - at least 40mm in one direction, square is probably the best. They need to be at least 600mm long - a metre is better.

Wet wood handles on any metal tools.

In the case of manipulating glass at slumping temperatures, you need two soaked pieces of timber. If you try to manipulate with one stick you will just push the piece around the kiln. Two sticks allow you to move the glass on opposite sides of the mould toward or away from each other without shoving things around. Glass is amazingly stiff at slumping temperatures. You will wonder how it moves at all when you have to use so much pressure to affect the piece!

Note also that the timbers must be soaked. If they are not they will certainly leave marks on the glass.

When the timbers began to smoke, it is time to close down the kiln - whatever manipulation stage you are at - and let the kiln heat up again while your sticks get wet again.

You need a second person to help with this kind of manipulation in the kiln. They are the door holders, fetch and carriers and anything that needs to be done while you are pushing the glass around the mould. Perhaps after a few trials, you would be able to do it without help, but it is always easier and safer to have help.

Strain Points and Annealing Ranges

I received the following question a while back and thought my response might be useful, although very informal.

“Can you dumb down the concepts of 'annealing point' and 'strain point'? I understand anneal point to be a fixed point (depending on the glass) but the strain point is a range...is this correct? I understand the concept of a hold at the anneal point but I'd like to understand how to bring it down through the strain point.”


I really dislike the idea of dumbing down concepts in kiln forming glass. Glass chemistry is incredibly complicated. Glass physics is still little understood. Glass is a very complicated subject. The marketing of glass for kiln forming has led us all to think it is a simple matter of recipes. Well it's not.

Having got that rant out of my system.... Let’s go ahead.

The annealing point is roughly defined as the temperature at which the glass (if it is the same temperature throughout) will relax most quickly. In the practical kiln forming that we do, it is not possible to ensure that the glass is that temperature throughout. So it is better to think of an annealing soak at the annealing point to allow the glass to become a more even temperature throughout its thickness. As thicker glass means the heat has further to travel from the centre to the surfaces, a longer soak is needed for thicker glass.

The annealing occurs during the slow cool past the lower strain point. The annealing occurs best with a slow, but steady drop in temperature. So annealing is occurring over a range, not at a point. We all rely on a combination of the manufacturers' recommendations, various writings we read, and experience to determine that rate, although Bullseye have published a chart which is most helpful, whichever glass you use.

Strain points.

There is an upper and lower strain point, although this is disputed by some. There are mathematical definitions for these as well as observational definitions. I do not understand the mathematics of either. In lay terms, the lower strain point is that temperature below which no further annealing can take place. It is safe to assume this is 50C below the annealing point (I think it actually is 43C, but I'm not certain of this number).

So it is safest to control the cooling to at least 5C below the lower strain point. Bullseye find that cooling from the annealing soak to 370C is best - this is much more conservative than is theoretically required – 146C below the annealing soak point. This does take care of any problem of thermal shocking of the glass during the cooling.

The upper strain point might be more properly described as a softening point. This also has scientific definitions. The way I think of it is as being the temperature above which no annealing can occur. Another is to think of it as a point beyond which the molecules of the glass are in relatively free motion - which increases with temperature. This again can be considered (on the rise) as 50C above annealing. However on the way down it is safer to consider it to be not more than 30C above annealing. This is because the glass temperature lags behind the air temperature (which is what our controllers measure).

So there is no point in soaking more than 30C above annealing in an attempt to equalise the temperature throughout the glass. However, if you really need to equalise temperature at some point above the annealing point, it might be better to slow the cooling from the working/top temperature and do the final equalisation of temperature at the annealing point.

To answer directly, the strain point by definition of language cannot be a range. There are two points which form the possible annealing range, although the lower one is the critical one. The upper one I described earlier as the softening point. The softening point forms the upper part and the strain point forms the lower part of a range in which the annealing can occur. So the concepts are the opposite of what you propose. They are points which are the boundaries of the annealing range.

To complicate things further, not all glass from one manufacturer has the same annealing point. The published annealing point is a compromise that their experiments and experience have shown to be most suitable. Bullseye glass for example has three annealing points, 532C for opals, 505C for cathedrals and 472C for gold bearing glasses. NOTE: these figures may not be exact; they come from memory rather than documents. Since this list of annealing points was published, Bullseye have conducted further experimentation that shows the best annealing soak occurs at 482C which is below transparent and opalescent, but above gold bearing annealing points.

Schott recommends a range for annealing, not a point, to accommodate these variables. Bullseye, Uroboros, and Spectrum have published annealing points that are practical for people kiln forming in smaller kilns that are less well controlled than the factory lehrs.
If you look at the Bullseye site - education section, you will find a lot of useful information. Especially informative are their tech notes. Spectrum - to a lesser extent than Bullseye - gives helpful information. The information from both sites should be absorbed and the principles applied to other glasses.

Finally, kiln forming is deceptively simple. I have spent 29 years discovering how much more there is to learn. This is one of the reasons that glass is such an exciting medium - people keep discovering new things.

Reviewing the above, I realise that I have not answered your question "... how to bring {the temperature} down through the [lower] strain point". My answer is that you should look at the manufacturer's site for each glass that you use. Look at their rates for annealing for different thicknesses of glass (some also take into account the size). Consider them. Then look at some of the other sites for their published annealing rates for various thicknesses. Comparison of their rates will reveal differences. Think about what they are, how they relate, and whether they reveal that they are using the same principles with slight variations.

Also, if you can, get a copy of Graham Stone's book "Firing schedules for glass, the kiln companion". It provides a handy guide to annealing rates. But DO NOT use it as a book of recipes. Read all the commentary about the schedules, as they (combined with the introductory parts) give principles and tips about how to think about the cooling of the glass.  Bob Leatherbarrow has recently published an excellent book on kilnforming schedules, available from his website.

By the way, experience is so often lost, or misremembered, that keeping a log is essential. My first log consisted of loose leaf binder, so I could file all the same kind of firings for various glasses together (this was in the days when there was not much fusing compatible glass, and I couldn't afford Bullseye at UK prices. I was discovering lots about glass firing and using some schedules that I now wonder how I had any success. I did learn a lot from my failures and recorded them too. Now I use a log, usually an out-of-date A4 size diary, sometimes a manuscript book that is big enough to record observations and illustrations. Bullseye have a good record form on their site.

I congratulate you on your desire to understand the processes. Too many only want to put the glass in and turn the kiln on. That is the desire a number of kiln manufacturers pander to when they put pre-programmed schedules on the controllers. So, don't take any of this as criticism of you or your comments. It is meant in a constructive manner - even though I am told frequently that the manner is blunt, even rude.

Best wishes on continued successful kiln forming.

Revised 22/06/19

More detailed information is available in the e-book: Low Temperature Kilnforming.

Applying kiln wash

Applying kiln wash to shelves and moulds have the same requirements.

The kiln wash must be applied evenly

You can use a soft bristled brush like a hake and trail on the kiln wash in four directions – top to bottom, side to side, and diagonally left to right and right to left.

The pigmented kiln wash turns white, indicating that the shelf has been fired

You can also spray the kiln wash onto the shelf or mould. This can provide an even coating, but you must be careful to avoid puddling the kiln wash. Pause for a few seconds after each coat to allow the water to be absorbed before applying the next coat. Apply until the shelf or mould surface is not obvious through the kiln wash. There is no need to dry between coats.  The best coverage is achieved by applying all four coats in different directions at the same time.

You can use a sponge to apply to flat surfaces. A light touch is required. You need to apply in various directions as with the brush.    

Metal moulds are a special case. The water carrying the kiln wash will simply bead up or run off the metal. First clean the metal to get rid of oils and dirt – sandblasting will do well. Then you need to heat the metal to about 125C – 150C (ile., above boiling) and brush or spray the kiln wash onto the mould, one coat at a time. Return the mould to the heat source and then apply another coat of kiln wash. Do this until you have an even layer of kiln wash. Be careful not to put so much liquid on the mould that it begins to run. If this happens, you really need to start again.  Also if the metal is too hot, the water will boil off, leaving bare patched.

Apply the kiln wash thinly

You need enough kiln wash to separate the glass from the carrying surface. Any additional kiln wash will not make for a better separation, but may begin to flake off the surface and adhere to the glass more or less tightly.

The usual recommendation for brushing is one part kiln wash to five parts water. I recommend ten parts water to one part kiln wash if you are spraying the kiln wash. If you have a really absorbent surface, such as a vermiculite mould, you can reduce the water to two and a half parts water to one kiln wash. All these measurements are by volume.

The kiln wash finish must be smooth

There are several ways to smooth the surface.

You can rub your hand over the shelf or mould to remove high spots/streaks. You need to remove the dust before using though.

You can smooth the surface using a rolled up nylon stocking. This relatively open weave allows the powder to be captured in the material. It works well on irregular surfaces like a mould. Again you must clear off any remaining dust.

Another way is applicable to flat surfaces. After applying the kiln wash, but before it has dried, make sure the surface is level. Then brush or spray on a layer of hot water. This both puddles and evaporates quickly, leaving a smooth surface on thinly applied kiln wash. If the kiln wash is thick, the drying process will leave cracks as in a dried-out river bed.

Multiple firings of kiln wash

Iridescence

What is it?       How permanent is it?

“Many special effects can be applied to glass to affect its colour and overall appearance. Iridescent glass … is made by adding metallic compounds to the glass or by spraying the surface with stannous chloride or lead chloride and reheating it in a reducing atmosphere.” 

Older glass can appear iridised because of the light reflection through the layers of weathering.

“Dichroic glass is an iridescent effect in which the glass appears to be different colours, depending on the angle from which it is viewed. This effect is caused by applying very thin layers of colloidal metals (e.g., gold or silver) to the glass.”

Source: https://www.thoughtco.com/

A rainbow iridescent appearance caused by an oil film on water is seen by light being reflected from both the top oil surface and the underlying water surface.  The light reflected from these two surfaces or boundaries have slightly different wave times and so interfere with each other to create this colourful pattern.

This is also observed in soap bubbles.  Here the light is reflecting from both the inner and outer surfaces of the film.

This iridescent appearance is termed thin-film interference.  It is an occurrence in nature where there is a thin film through which light can penetrate and so reflect off the surfaces of the film.  These surfaces are termed boundaries where the light can reflect. 

The thickness of the film can enhance or reduce the iridised effect. 

At a certain thickness the light waves reflected can cancel each other out.  This is described as a destructive interference pattern as it reduces the reflection.  The phenomenon can be used to provide non-reflective surfaces.

At other thicknesses there is an iridised effect.  This is caused by the reinforcement of the recombination of the two light waves reflecting in phase or nearly so.

Control of the thickness can give the silver or the gold iridised appearance, as in the Bullseye iridised glasses, in addition to the rainbow and other effects.

The nature of the light affects the colours of the iridescence.  If the light is daylight or similar it is a combination of many wavelengths.  The different wavelengths reflecting from the “boundaries” or surfaces provide the multiplicity of colour.  If the film has variations in thickness, there will be variations in the colours created.

A diagram from Wikipedia shows how the reflections work at the microscopic level.

https://en.wikipedia.org/wiki/Thin-film_interference

The permanence of the film causing the iridisation appears to be dependent on the metals used and the way in which they are deposited.

Why Sell Online?

"Why not? Everyone else is doing it."

The more interesting question and response is:

“Why do it at all? There are lots of other ways to sell.”

The first thing you need to help you decide whether online is for you, is a plan for selling.  You need to think about how you sell. Selling needs to part of whole strategy that can involve multiple ways and avenues of selling. The ways you sell your goods needs to be integrated into social media - whatever platforms you decide to use to sell.  One platform will not be enough.  You need to look at where the main effort will have most return.

Planning a selling strategy

Initially:

Even before you have a whole selling strategy worked out, you need to be using social media to promote your work.  A blog about you and your work is a good place to start.  It gives you a presence, a personality, a brand. Write regularly about your craft life.  Share it with your friends on Facebook, Twitter, etc., and ask them to share it with their friends to get it known.

Linking to and from that blog using Facebook, Pinterest, Twitter, and other social media platforms help to spread the knowledge of who you are and what you do. These are the things you need to do whether you decide to join an online marketplace, a stand-alone shop, or stay with physical sales points.

Making an online selling plan:

The first part of the planning is to decide why you are going to sell online, rather than stick with just bricks and mortar sales locations. These physical locations include galleries, museum shops, gift shops, craft fairs and exhibitions, etc. Some questions to ask yourself are:

• What do you gain by interacting with shop owners and direct customers? 
• What might you lose by going online?
• How does online fit your products?
• Will you need to put in more, or less, effort online rather than selling in physical locations – shops, craft fairs, etc.?
• Where is your market located? Local? Dispersed?
• Is your market a specialised or a general one?
• Will your products stand up to delivery company handling?

The answers to these questions will help you decide if online will help sell your products.  It may of course throw up ambiguous answers – on one hand, on the other hand kind of answers.  This would indicate a mixed platform approach is desirable.

       

But, just a minute!

Don’t sign up to an online marketplace just yet.  There are some things you need to prepare before searching out the appropriate site or sites for your work.

Products:

Yes, you have a lot of different things you could sell. Think about where you want to concentrate your efforts.  A few key products will help to give your work an identity.  It will help you define, and so reach your customers.  It will focus your marketing and build your experience and reputation. 

Online enables you to concentrate on niche marketing more successfully than bricks and mortar can.  It is one of the main advantages of online selling. Once you have identified your products and therefore your market, communicate with them.  Think about their interests, needs and desires as you write.

Work on describing a strong identity – often called a brand. This should be accomplished in a short sentence. Know who and what you are. Tell your values, your story to the world. But especially to your potential customers.  Follow this description up and re-enforce it with photos and descriptions in all areas of social media. This will then be a style to carry over to the online shop, if you decide to set one up. And even if you don’t it will improve your selling at physical locations.

Prepare product titles and descriptions:

Clear titles and descriptions are needed for each item. These should be direct using simple language making it possible for the viewer to understand immediately what is in front of them. These titles and descriptions should include specific words - terms, tags, keywords - that the prospective buyers might use to search for your products.  You should include lots of tags for the photos and descriptions, but they must be relevant.

Include all the detailed information – size, colour, materials, price, delivery mechanisms and costs, projected arrival time, etc. – in the description, but toward the end when they have probably already almost made up their mind. 

Excellent photos are required.

The main descriptive element when the buyer gets to your page or listing is the pictures.  They must be descriptive of all the elements of the piece – several images per item is a good idea.  Consider a professional photographer to make these images.  They have an independent eye and can see things from the buyers’ viewpoint.  In addition, they can take better pictures.

Share these descriptions and images on social media.  This all needs be done before you join a marketplace website.  It helps to test your abilities to present your products successfully before you commit to online.  It will help you in your presentations of your work where ever you place it.

Costing and pricing:

Of course, there is the boring bit – deciding on the price.

These include factual elements:

Costs of production - materials and time, overheads, administration of the materials buying and the object’s selling processes.

Applying this cost information to each item will give you your break-even price.

You then need to consider what profit you want to make for your effort. This might be done as a margin on each piece, or as a part of your desired annual income.

The break-even plus the income or profit factor will give you the wholesale price.  The retail price is at least twice the wholesale.

Will the market bear that price?  Compare similar products and test your pricing with potential customers. If your price is too high, return to the design of the item and consider how it could be simplified. Alternatively, consider how it could be enhanced to achieve an even higher price for little more effort.

If your product is the kind where purchase of multiples is possible or likely, give yourself enough margin so that you can offer discounts for quantity purchases.

Also think about whether yours is a luxury product. If it is, the price needs to be higher than for general work.  E.g., if your jewellery is set in silver, it needs an extra margin for the luxury element of the item.

Cost of delivery – packaging, time, delivery charges. You need to decide if you are you including this in the price, or is it separate?  This will need to be reflected in the price, or the cost of delivery must be stated in the description.

Benefits

This process of preparing for online selling will benefit your selling, even if you decide against online selling.  It will clarify your offering to the potential customers.  It will help to define you as a producer and develop the awareness of your products. It will assist the customer to understand your story and your work, so encouraging them to buy.

A discussion of choices about choosing a website is here.

Preparing for a Craft Fair

“What should I take to the craft fair?” 

This is a frequently asked question.  The question gets a variety of answers from the materials to make the stand out of, the variety of supplies, to taking a variety of things to the show with different price points.

I’m sorry to say that the last piece of advice leads to set ups that look more like a jumble sale rather than a display of finely crafted works.  These stalls have a lot of closely arranged pieces to fill the space.  They have a lot of price points.  They have a wide choice of colours in each range.  What is the potential buyer to make of so much choice?

It is important to have an identity on display.  Are you a maker of votives, table ware, suncatchers, garden objects, panels, recycled and repurposed glass, etc.?  If they all are displayed, it is difficult for the viewer to determine what it is that you do.

This identity can be a unified colour range throughout the items you are selling.  It could be a range of bowls, platters and other table wear with a consistency of colour or design.  It could be your concentration on making objects from recycled glass. Essentially, you are telling the viewer what you are about.  It could be from “I make jewellery” to “I make glass objects in a range of blue green” (not that I think the latter is a real identity, but it is a possibility).  This “identity” can change from venue to venue, of course.

The usual way shops and stores distinguish their important items, is to give them display space.  This is vital for craft shows too. Space around items allows each item to have its own significance.  It is possible to give this space by concentrating on just a few lines of work.  You can always have spare stock under the table or out back to fill the gaps caused by purchases.

You may decide to go for the jumble sale approach. One of the reasons might be the people coming will be looking for lower priced objects. (Should you be selling your pieces at bargain prices?). You may be unsure of the nature of the visitors to the show and want to appeal to a wide range of people. You still need to give each piece its space.  You may have a range in multiple sizes and colour ways.  Display only one product in the full range of sizes and only a single item in each of the colour ways.  Your “under the counter” stock will fill in the sizes for the colour range.  In this kind of way, you can make space for each item even when you bring a multiplicity of objects.

So many times, I see little evidence of descriptions relating to the object or range of products.  You need to illustrate the thought you have put into the creations by the descriptions you give to the pieces.  Simply putting the pieces out in a nice arrangement is not enough.  You need to tell people what it is, the concept that led to its development, possible uses, how it might fit into a life style and its benefits – unique art piece, display of the owner’s ability to choose beautiful objects, etc.  And of course, you need to give the price.  You might also want to make it possible for a buyer to have it shipped, so you need information about delivery costs as well.  In giving this kind of description, you are showing you have put thought into the piece and into the buyer’s needs too.

It is very unusual to see anything about the maker.  Unless people are looking for bargain basement items, they want to know about the maker.  They are buying your story almost as much as the object. You have a story relating to your life and your approach to making.  Tell it. Display it prominently.

Where else can your products be found?  People want to be assured that they are buying things in demand. Telling where else your creations are sold helps assure them that their choice is validated by other people’s interest (even though they are buying a unique piece).  Put this information in a few sentences and put it up somewhere on your stand.

Telling people about where you can be found in the real world, on social media, your blog, and any online marketplaces is important.  Often people can turn into repeat buyers through maintaining contact. At the least it can promote continuing relationships, which may turn into commissions.

Research the market. You need to look at the profile of people that will be attending the event.  If it is a gardening event, you might take garden-based objects, or set your pieces in a garden-like atmosphere. If it is a school event, think about the background of the parents.  If it is a stand-alone event, then you need to think about the population of the area, or the people that the event will draw.  The organisers in all these cases should be able to give you information on the people who are likely to come. 

Take things that will appeal to the people who will be browsing and arrange them appropriately to the event as well as getting the display right.  This might involve different table coverings, or backgrounds to reflect the ethos of the event to which the craft fair is attached.  You need to make a connection with the potential buyers.  Show that you are tuned into their lifestyle.

Preparing for a craft selling event is much more than what structure to hang or display your work on.  It is about reflecting the environment of the event. Will the people be browsers that need to be converted to buyers, or are they going to be coming to buy? Those two groups have different display requirements. What your identity will be in relation to these buyers will determine the range of material you bring to the show. 

Summary

A craft fair is very similar to a shop display or your offering on an online craft marketplace. 

• Your display needs to immediately say what you do. This is assisted by the walls, coverings, etc. of the stand, but is most importantly shown by the selection of objects to show.  This is what tells people what you do.  It is your identity for the time being. 
•  
• You need to lovingly describe each object on display. This gives the buyer a feeling for the concept behind the item, an idea of the benefits and value of it to their life.
•  
• You need to tell your story. They are buying an idea of the maker as well as the object.  It is a good idea to tell people where else your work can be found too – even if it is at other craft fairs just now – but especially if you are on any online marketplaces such as Etsy.  Engaging them with your social media is also a good idea to help maintain the currency of your story.
•  
• You need to find out about who will be attending the event.  The social and economic characteristics, the age profile, the status of the event and many other things will be important to what you bring and how you dress it.

Finally, all these elements of an approach to selling your work apply to anything you are thinking of selling on an online craft marketplace.  Getting it right at craft fairs prepares you for successful online selling too.

Hot Spots in the Kiln

You may suspect you have hot spots in your kiln because of bubbles or one side of the piece being more fully fused than another. A good method for determining the temperature distribution across the kiln is given on the Bullseye site.  It does not require any sophisticated equipment – just supports equal distances apart and strips of glass equally wide and long – to be witnesses for the hotter and cooler parts of the kiln.  You fire slowly to a very low slump temperature – ca. 620C - for only 5 minutes.  Go as fast as possible to the annealing point and soak for 15mins. Then you can turn the kiln off, and let it cool as fast as the kiln can.

This test will show where the hotter areas are.  You will see from the test results that there is a gradual change of temperature across the shelf, rather than small hot areas that would be required for localised large bubbles originating from under the glass.  It will tell you where the cooler areas are, so you can avoid placing pieces in that area when you need precise profiles on the finished piece.

There is little to no relation between hotter areas of the kiln and localised bubbles.  Do not think hot spots are the cause of large bubbles.

Bubbles more often relate to:

Bubble squeeze

Alack of an adequate bubble squeeze, as described here.

Avoidance is the best approach.

Do not be lead into the idea that mistakes are automatically art, or that all of them can be rescued.

Rapid firing rates

Firing rates need to be adjusted to the materials you are firing.

As fast as possible firing rates can cause problems.

High temperature rapid firings can also cause problems.

Rapid firings are more likely to harm the glass than the kiln.

Damaged shelves

Distortions or damage to shelves can trap air and so cause bubbles to form between the shelf and the bottom of the glass.

Checking for flat shelves and fixing.

There are some remedies.

Volume control

Varying volumes within the piece can give problems.

There are a variety of related things that can cause large bubbles.

Glues

Glues and adhesives have a variety of effects and dangers, especially if generous amounts are used:

There are a variety of glues each with their own characteristics.

Uneven layers/layup

You must think of ways for the air to escape from the interior of the glass and from under the glass.  Most often we set up things in a way that creates bubbles. There are two main ways that we do this.

Encased items

When we put glass or other materials between an upper and lower sheet of glass we are creating conditions for bubbles to form.  The encased items hold the upper glass above the lower glass by an amount related to the thickness of the inclusion.  Routes for the air to escape must be planned. 

One of the ways to reduce the height of the space taken up by the enclosures, is to fire upside down with the inclusions on the shelf. This allows the glass -which will be the bottom layer - to form around the materials, reducing the air space between the bottom and capping layer.  This is known as flip and fire.

You then clean the face which will be capped very thoroughly.  Place the capped piece on fiber paper – which can have Thinfire placed over it, or coat with kiln wash.  This is to allow the air in the uneven bottom surface to escape from underneath through the fibre paper.

Weight

Even when there is no encased material, the weight of the glass pieces on top can create areas where the air can be trapped.  On a single layer the arrangement of pieces can create areas where the glass cannot resist the air pressure that cannot disperse from the pockets caused by the glass on top.  Very clear and generous exits for the air are required.

This can happen with two layers as well, although usually a higher temperature is required.  A means of avoiding large bubbles when there is glass – powders, frits or pieces of glass – placed on top is a two-stage firing of the piece.  First fire the base layers together at full fuse so they become one whole.  Then add the decorative elements on top and fire.  Remember to fire more slowly than for two unfired layers.  The main piece is now 6mm thick and needs a slower rise in temperature.  The additional heat work this entails may mean that a lower top temperature, or a shorter soak will be required than normal.  You will need to peek at intervals to check on the progress of the firing.

There is a multiplicity of ways that bubbles large and small can be created.  Careful layups, bubble squeezes, slower rates of advance and lower top temperatures can minimise, but not always eliminate, bubbles.