So, first of all, you'll need a kiln. Hah - that'll stop many of you from stealing my business RIGHT THERE. But for those of you still interested, there are a lot of different kinds of kiln on the market, from great big ones that you can also use for pottery (and which generally cost four figures) down to the so-called 'hobbyist' ones which are much more affordable. You can even get ones that fit in a microwave oven these days and cost under 100 quid. I myself use a Paragon SC2 kiln which was bought for me as a Christmas present a few years ago by The Lovely Husband. It's still pretty expensive but if you shop around you might find a secondhand one on eBay. Please note the small fire extinguisher in the bottom right hand corner. Always good to have one handy, just in case, you know?
Next - glass. I get all my supplies from two places - Warm Glass UK and Creative Glass Guild. In fact you can get everything you need to make glass from these two companies. The important thing to remember about fusing glass is that the two (or more) pieces you want to fuse have to have the same 'Coefficient of Expansion', or COE for short. This is a bit technical but basically is to do with how quickly glass expands when heated. Some glass does it at a different rate to other glass. If you try to fuse two pieces of glass with different COEs then they can suffer thermal shock and shatter. However it's all made very easy by the glass being labelled with a COE number, so you just ensure you use only glass with the same number - simple. I use COE90 glass.
Dichroic Glass - I'll just post the Wikipedia entry here for you: "Multiple ultra-thin layers of different metal oxides (gold, silver, titanium, chromium, aluminium, zirconium, magnesium, silicon) are vaporised by an electron beam in a vacuum chamber. The vapour then condenses on the surface of the glass in the form of a crystal structure. This is sometimes followed by a protective layer of quartz crystal. The finished glass can have as many as 30 to 50 layers of these materials yet the thickness of the total coating is approximately 30 to 35 millionths of an inch (about 760 to 890 nm). The coating that is created is very similar to a gemstone and, by careful control of thickness, different colours are obtained." It was also said to have been invented by NASA for use in the gold-coloured visors of astronauts' helmets, which is a neat selling point when talking to customers. Dichroic glass has the unique property of showing different colours depending on whether the light is reflected or refracted. Think oil on water, bubbles, butterfly and beetle wings. In one light it's gold, turn it slightly and it's green. Or purple. Or pink. You can get sheets of dichroic glass in all one colour, or with a rainbow mixture, or with patterns or textures, on a black background or clear. It is, however, expensive to buy, so I only buy small 10cm x 10cm sheets as a rule.
Tools - You don't really need that many tools. I use a self-sealing cutting board, red plastic running pliers, a metal ruler and an oil-filled glass cutter. I've found through trial and error that the oil-filled cutters are the best. It's also recommended that you get some eye protection - those plastic goggle things will do but I wear glasses anyway so don't bother. You'll also need to do something with the inevitable little flakes and splinters of glass. I actually just sweep them with a paintbrush into an old plastic coleslaw pot after every cutting, otherwise they get stuck into the edges of the palms of your hands, which is NOT GOOD. I also have some grozing pliers which you use for nibbling edges but we won't be needing them for this tutorial. You'll also need some glue which we'll discuss later.
Right - let's get started, shall we?
We're going to make bog-standard, smallish round cabochons from one colour of dichroic glass with a clear layer on top.
1. Onto your cutting mat, put the glass you want to cut. In this instance I'm using a glass that will end up sparkly purple at the end.
2. I've lined the long edge of the glass up with the 3-8 black line on the cutting board - this will help keep everything straight. I've decided to cut the glass two squares deep (according to the cutting board, you can, of course, cut it to whatever size you damn well like). Lay the metal ruler along the line you want to score along.
3. The oil filled glass cutter has a little wheel at the tip - see? Leaning firmly and with even pressure on the metal ruler, run the little wheel on the cutter along the edge of the ruler. The 'rules' say you're meant to cut away from the body but, hey, we don't need no stinkin' rules here, amigos! I naturally find it easier to cut towards me and have never had any problems, but try it both ways to see what suits. These pictures are a little alarming because it seems I have somehow got my mother's hands at the end of my arms (except she has better nails than me), which I don't recall happening...
You need to press hard enough with the cutter so that you hear a noise a little like ripping silk. It's hard to describe but very distinctive. This indicates that the glass has been successfully scored.
You can see where the oil from the cutter has left a little line on the glass.
4. You can, if you like, now turn the glass over and tap along the back of the score line and hope the glass will break, but I prefer to use the plastic running pliers. It's best to get a pair that have a white line marked on one side. This is because you line up the white line with the oil line on the piece of glass and, very gently, squeeze the handles together. The glass will split (hopefully) along the line.
5. You now have a thinner strip of dichroic glass. This now needs to be cut into smaller pieces that you're going to fuse. So you do the same thing again - take the metal ruler and use the oil-filled glass cutter to score along the lines that you're going to use the plastic running pliers to break. Again, these pieces are roughly two squares of the cutting mat in size.
6. You now have a batch of small evenly sized (hopefully) pieces of dichroic glass to form the base layer. You will now need to give each piece a bit of a clean. As you can see from the picture, there is a distinctive thumbprint on the piece just above the one that has the flash flare on it (you might have to click on the picture to make it bigger to see this). This needs to be removed - fingerprints will show up in the finished piece if you don't and you'll be cross, so clean it now and all will be well. I actually just use a piece of kitchen paper. Be careful - the pieces may be small but the edges are still cut glass and therefore sharp.
7. That's the base layer dealt with. You now need to make the top clear layer. Basically, you just repeat everything above but with a sheet of clear glass. I use 1mm thick clear glass but you can also get 2mm and 3mm thicknesses. You can also get tinted clear glass which will alter the colour of the dichroic underneath it, but that's for experimenting with later. For this tutorial we'll just focus on your bog-standard clear glass top layer. You'll need to cut the little glass squares a bit bigger than the base layer. If the base layer thickness is 1mm, then you need to have at least 1mm overhang on the top layer on all sides to ensure proper coverage all round. However you can get interesting effects if you make the top layer a bit smaller as the base layer comes up around the edges of the top instead of the other way round (if you see what I mean, which you probably don't until you have a go yourself). I did take a load of pictures of scoring and cutting the clear glass but, basically, they're the same as the ones above and I'm sure you're all intelligent enough to understand that concept, so I'll just post the one here where I'm breaking the glass.
Let me introduce you here to the fabulousness that is the Las Vegas Tin Tray. I bought this in, well, Vegas actually, back in 1996 when The Husband and I got married and I never really knew what to do with it until I discovered it was the perfect size for transporting my little piles of glued glass down from my workshop to the garage where the kiln is located, and I use it all the time now. If you can see, amongst the gaudiness, I've put the nine little squares of dichroic glass onto the tray.
8. Onto each of the base layer squares, put a drop of glue. I use Glastac but there are other kinds you can use such as Elmer's Fusing Glue which is white and thicker than Glastac but both burn away in the kiln. You can, of course, use nothing at all and just balance the glass but that can be precarious, especially when you have several layers. Glue each layer separately for peace of mind and lack of swearing.
9. Onto this you then pop a square of clear glass. The glue holds the two pieces together making it easier for you to move the finished piles around without them toppling over.
10. Now you leave it all to dry for a bit. You can cut more glass in the meantime or leave it overnight, or do what I did for this blog which is to go and take photographs of honeysuckle clambering over my bridge
11. You now need to fire these babies. The inside of the Paragon SC2 kiln is not really terribly large. The white walls inside are very thick because that's where the heating element sits. The black dot thing on the back wall is the thermocoupling device (basically the thermometer/ thermostat thing that tells you how hot the inside space is) and you musn't put anything up against it. The little tubular column things are stands that you can get from kiln suppliers. Like the average kitchen cooker, a kiln has temperature variation within the space. In my kiln's case, it's hotter in the middle and nearer the back wall. Also the outside ambient temperature (i.e., if it's winter or summer) can also affect firing - you may have guessed there's a lot you can't actually control when firing glass, which makes it all rather exciting and mysterious.
12. I have some little kiln shelves that are designed to fit into my particular kiln. Whatever you do, DON'T put the glass directly on to the shelf and fire it because it will fuse to the shelf and you won't be able to get it off. There has to be some kind of protection between the shelf and the glass. This is the same as in firing ceramics and, traditionally, something called 'kiln/batt wash' or 'shelf primer' is used (in fact you would still use this if you were using moulds to heat slump glass sheets into to make bowls, etc., but we're not doing that here). But I use Bullseye Thinfire Shelf Paper instead. This is, as the name suggests, paper that you can get pre-cut to fit Paragon shelves or a bigger roll (which is cheaper) that you cut to fit yourself. I put a piece of the kiln paper onto the shelf and then put the piles of glass onto that. Normally I would cover the entire shelf with cabs to be fired but I'm just doing a few for this blog. If you click on the picture you may be able to make out the letter 'S' that I've written onto the paper in pencil. This is because the paper is fractionally smoother on one side than the other, and I want the smoother side against what will become the back of the cab, for a smoother finish (can I stop saying 'smoother' now? It's a weird word to keep looking at...) You can also only use each piece once.
13. Firing - this is the seriously technical bit and where the most experimentation will come in. Basically you have to get the glass to a temperature where it starts to melt and hold it there (known as 'soaking' so that everything heats up to the same temperature), before cooling it down. But you can't heat it up or cool it down too quickly or else Bad Things Happen, like shattering and bubbles. You'll really need to consult the instruction booklet for your particular kiln for this. The beauty of the Paragon SC2 kiln is that, once you've discovered the settings that work for you and produce the effect you want, you can preprogramme 4 different programmes into it so you can use them in future. My full fuse programme is saved as programme 2 (programme 1 on my kiln does what's known as a 'tack fuse' where the glass remains 'lumpy' rather than smooth, and I have programme 3 for firing precious metal clay). I was describing the process recently to a friend and she understood it through the analogy of making toffee - it seems you have to anneal both glass and toffee in order for it to form properly. I understand 'annealing' to mean cooling slowly to relieve internal stresses after forming, i.e., less likely to shatter.
My programme for a full fuse in a Paragon SC2 kiln is this:
rA1 550 (this means the speed at which the temperature rises - 'ramps' per degree centigrade per hour - in this case, a rate of 550 degrees per hour)
oC1 540 (this means I want it to stop when the temp reaches 540 degrees centigrade at the rate of 550 degrees cent. per hour, i.e., it will take just under an hour to get there)
HLd1 0.00 (this means I want it to hold/soak at that temperature for 0 time at all)
rA2 Full (this means that I then want the kiln to ramp up the temperature as fast as it will go...)
oC2 850 (...until it reaches a temperature of 850 degrees centigrade which is when the glass will start to melt)
HLd2 20 (then I want the kiln to hold/soak it at 850 deg C for 20 minutes)
rA3 Full (I then want the kiln to cool down as fast as it can...)
oC3 516 (...to a temperature of 516 deg C...)
HLd3 15 (...and hold it at that temperature for 15 minutes - this is the annealing section)
END (then the kiln switches off)
You can fiddle around and adjust all the ramp speeds, the temperatures and the holding times until you get something you like. This can either be deeply frustrating or excitingly experimental.
The whole firing process for my particular programme 2 takes 2 hours 11 minutes from switching the kiln on to when it automatically switches itself off again. Choosing different temperatures, ramping speeds and holding times will affect the length of the programme, but this one works well for me.
Obviously it takes a while after that for the shelves to cool enough for you to take them out and I would suggest leaving the kiln door shut until the red LED temperature readout gets to about 300-350 degree C and then you can open the door a bit to let the inside cool down quicker.
The 'red' picture above was taken through the window of the kiln while it was doing the second hold at 850 degrees, and you can see the edges are started to soften and round. Interestingly, glass wants to be a quarter of an inch thick and round so you don't need to shape the cabs at all, they automatically make themselves round.
14. Final product - and this is what you end up with. Neat, round cabochons that you can then do what you like with. A good option is to stick them to sterling silver earring flat pads/stud bases with a good clear 2-part epoxy resin to make a pair of stud earrings. You can get a reasonable idea of the colour change from this picture - there's a mix of dark blue, purple and pink in these particular cabochons. A final word, the shelf paper has to be washed off the back of the cabs but pick them off and wash them individually and put the rest of the used kiln shelf paper in the bin. DO NOT INHALE THE DUST as it is very irritating to the lungs and will make you cough like a bastard. Wear a mask if you can be bothered or do what I do and hold your breath while brushing off the shelf. DO NOT WASH DOWN THE SINK OTHER THAN THE LITTLE BITS OFF THE BACK OF THE CABS - it's weird stuff and will clog up the pipes.
Well, that's it, it's taken me all day to write this so don't say I never do anything for you people. I'm happy to answer any questions now, class....