Sunday, 17 May 2009

How to fuse Dichroic Glass

Okay, pipe down at the back there. Now, in the past, I've turned a blind eye to the deafening wall of silence from you all regarding my jewellery. I can no longer ignore the clamouring chorus of absolutely no-one saying, "But, Mrs Jones, we luuurrrvve your stuff - tell us please how to make cabochons of dichroic glass - PPPPLLLLLEEEEEEAAAAAASSSSSEEEEE???". You've worn me down, truly, so I've decided to acquiesce to your demands and provide a tutorial on how to fuse dichroic glass. With pictures and everything. I realise I'm giving away the 'secrets' (not really, anyone can find out via Google) of my trade and that you'll all rush out and make nicer cabs than me and sell them all for a fortune. But I've not posted for a little while and this'll do.

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

and Sylvester

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 ( 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....


Zoë said...

Fascinating stuff!

lampworkbeader said...

Very interesting. I've tried slumping a few times but always go back to using my torch. have you tried drilling holes in the glass before putting it in the kiln? You can get some very interesting effects.

Mrs Jones said...

Hi lampworkbeader - no, must admit I've not tried drilling holes - how would that work? Would the glass not shatter?

Preseli Mags said...

Utterly fascinating. I have fused glass to ceramics, but that was always a bit hit and miss (and basically involved bits of old beer bottle). I loved all the descriptions and pictures (and Sylvester too, cute cat!)

Maureen said...

Well ! mrs Jones ! you made that seem so easy, but we know it's not really. It's all clever stuff and very pretty too.

mountainear said...

Now I want to have a go - you make the process sound do-able. Very interesting.

Mrs Jones said...

Bless you, Maureen, but, honestly it really is that simple to do a basic full fuse. It gets a bit more complicated and fancy when you start adding layers and then making jewellery out of it by wrapping wire around them and that does, of course, take practice, but this is the starting place for all of it and if you've got the kit, I promise you, anyone can do it.

Mrs Jones said...

Hi Mountainear - yes! Do it! It's good fun. It was Toady over at the coo who said she'd got a small kiln and was thinking about fusing glass - hopefully she'll find this blog and it'll inspire her to have a go...

toady said...

Great tutorial.Got to get this week out of the way - craft fair and Chelsea, don't you know, then I've promised myself I'm going to have a go.

Calico Kate said...

Good luck Toady!
I nearly didn't look at this as the last thing I need to do is get hooked on to another craft. Th requirement of a kiln however has fortunately put me off this! I have done stained glass lead and copper work before and thoroughly enjoyed. These days I stick to sewing.
Absolutely fabulous blog though, well done.
PS love the bridge (where does it go?) and the cat!

Red Shoes said...

Wow, that all looks so interesting and the end result is lovely. Also lovely is the honeysuckle. I would love a space that included a bridge overflowing with honeysuckle. Gorgeous. And finally... Sylvester. O kitty, I am charmed.

seashell cosmos said...

How fascinating and completely gorgeous!!

Mrs Jones said...

Toady - yes! You must have a go! You can get smaller sheets and offcuts of dichroic glass on eBay sometimes, and the clear glass is dirt cheap, so now there's no excuse...

Calico Kate & Red Shoes - thank you for your kind words. The bridge - I live in a cul-de-sac of 3 storey townhouses (the ones with the garage underneath) and our side of the road is, more or less, built into the side of a hill, so the gardens are very steep and mainly terraced. Our sitting room, kitchen & dining room are on the first floor (2nd floor to our American readers) so at some point in the past a previous owner had the brilliant idea of removing the window in the back wall of the dining room (that overlooks the garden) and putting in a door instead, then building a bridge that takes you over to the garden. It completely turns the garden into another room for us as the door is permanently left open during the summer, and you don't have to go all the way down to the ground floor to go outside (there's another back door down there, onto the patio which is a bit damp and shady so I grow all my hostas and ferns (and a big tree fern) down there). We're the only one in our close that has bridge which is daft as it's such a fabulous idea. Was the clincher when we were looking at it with a view to buying back in the mid-90s. And Sylvester Bean (to give him his full name) is a huge fat sweet boy - I have many amusing photos of him.

Seashell cosmos - why thank you, I'm glad you like it/them.

Vic said...

So cool! I was honestly fascinated by the whole process, and the end result is beautiful.

Lampworkbeader said...

It's not difficult to make holes in glass if you have a really hard drill bit. Have a look at She uses the technique for her glass pendants and they're lovely.

Sue said...

hello, great article - thank you. I had a go at fusing but for some reason my cabochons stayed square! It was my first go and I think that I didn't make the top layer of glass big enough, could that be the reason? (the squares were only about half an inch big). Thank you

Mrs Jones said...

Hi Sue - I would have sent this to you direct but I have no contact details, so hope you come back to see if I've replied. Could be a number of things, it's probably most likely to be temperature that's the cause. If you try again, try firing at a higher temperature and perhaps increasing the length of time. Even if the top layer of clear glass isn't quite big enough to cover the top of the cab, it will all still round out.

Stephanie Doskas said...

Hi there!! I just discovered your blogl lol its awsome! I searched the whole wide web and found shit all on fusin glass....well nothing quite as clear and put simply. Thanks a bunch. Now I actually have to go out and get the stuff to try this out.
Stephanie D.

Mrs Jones said...

Hi Stephanie - thanks for the positive comment. I had the exact same problem which is why I did the post. Don't forget that my temperatures in the post are in centigrade and being in Canada I expect the temperatures you'll be using are in Fahrenheit so don't forget to convert them. Good luck - it's really not difficult but expect a lot of fiddling around with the temperatures and timing until you get something you like. It's also a good idea to have a notebook to write down the details of each firing so that you don't forget what you did when you do a good one.

Gifted Designs said...

Definitely interesting. If glass wants to be round, is it even possible to make square pieces???

Mrs Jones said...

Hi Gifted Designs - You can, of course, do it after firing, by grinding the round cabochon into a square shape and then putting it back in the kiln at a lower temperature in order to smooth the edges but that presupposes that you have a grinder. If, like me, you don't, then it's down to experimentation with temperatures and holding times - you need to find them where (if you're putting a clear glass layer on top) the glass will melt and the edges will just rounds (so there's no sharp points) but it doesn't melt enough to lose the shape. You could also fill a square mould but that would probably be for making bigger, more functional, pieces. I have my kiln set on 3 programmable settings for full fuse (which goes round) and a tack fuse (or semi-full fuse) which rounds the edges and semi-fuses/melts other smaller pieces on top but leaves them 'lumpy' so there's texture. If I'm lucky the overall shape remains square or rectangular, but even if I do the same thing every time, I don't always get the same result as things like the temperature of the room where the kiln is sitting can affect how a piece fires. There is a certain element of unpredictability to the whole process which can either be inspiring or frustrating...

Anonymous said...

would you have a programme for tack fusing? Also I use Bulleye thinfire but on some of my pieces of glass I get a white residue do you know why? Thank you.


Mrs Jones said...

Hi Laura - first of all, not sure what's going on with your kiln paper. I was going to suggest ensuring you bought the thinnest paper, but it looks as if it only comes in one thickness. If the residue is on the top of your glass, then perhaps the paper is curling over during firing and touching the top of the glass. To avoid this you need to weigh down the corners of the paper with either bits of scrap glass or kiln stands.

Now, the programme I run for my tack fuse results in items that are fused together quite a lot but aren't uniform, they're still 'lumpy'. If you want it to be even less fused, then you can lessen the temperatures and shorten the times. Plus remember that my programme might not work in your kiln - like kitchen ovens, they are all calibrated differently, but you might as well give it a go, it's somewhere to start from. Don't forget the temperatures are in centigrade.

Okay, my tack fuse programme runs like this:

rA1 550 degrees
oC1 765 degrees
Hld1 25 mins
oC2 516 degrees
Hld2 15 mins
rA3 0000

That's it - have a go and see if it works.

Boxofmisc said...

Mrs. Jones I am in awe of your beautiful jewellery and your ability to spend so much time and patience explaining how to make it ones self. You need never worry I would rather buy your expertise in the form of lovely things. It would take me forever to even get started. Thanks for your nice things.

Anonymous said...

Dear Mrs Jones, I just came across your wonderful informative blog as I was looking for something that would work in my newly acquired antique/vintage carved dragon which has coloured mirror as scales but many pieces are missing. How tiny can you make the cabochons? I think they could be the answer to my project.: D


Anonymous said...

I have made some pendant size pieces on a full fuse and now want to slump the backs slightly. Do you have a programme. Thank you.

Kind Regards


Mrs Jones said...

Ooh, Gwynneth - I'm so sorry to have missed your comment here (and I bet you won't get to read this either because you'll think I'm some snotty bitch who doesn't answer questions....). You can make dichroic cabs pretty damn small - the smallest I've gone down to is a few millimetres across but they will be quite spherical and not flat like scales. It might work but I think you'll have to experiment here.

Laura - ah, now, slumping is a WHOLE other ball game and one I'm struggling with currently, but with 3mm sheets of plain glass rather than fused cabs. You're going to have to experiment and I would practice on cabs that are not so precious. You probably only need to do a single speed ramp at full speed up to, say, 750 degrees centigrade, hold it for about 15 mins then turn the heat off and leave the door shut until it gets down to less than 200 degrees centigrade. You really only want to heat the glass enough so that it 'gives' and so it doesn't refire. I have no idea though if it will change the overall shape of the cab, for example, if it's slighly oval or rectangular, after heating it to slump it may come out more circular. It really is just down to experimentation but good luck - I hope you have better luck than I'm getting!

CT tech said...

When I fuse at 1425 degrees F for 10 minutes my cabs come out square. Is it the 20 minute soak that makes them come out round?

Val Spiers said...

You have me thinking that I need to fire to a hotter temp. We just bought a little kiln and we are getting an uncovered foily line around the edge of our earring rounds. We are still experimenting . It is such fun. I found your post very useful reading. Thanks.

Mrs Jones said...

CT tech - if you want your cabs to be rounder, I think you'll have to either fire them at a higher temperature and/or fire them for longer (a longer soak might also work).

Mrs Jones said...

Hi Val - try experimenting with a hotter temperature and see what happens but I think the uncovered foily line (and I know exactly what you mean) indicates that your top layer of clear glass needs to be bigger. Make sure that when you glue the glass pile together before putting in the kiln that the very top layer of glass hangs out over the edge of the pile by the same distance as its height, so when it slumps and fuses, the top layer covers everything. A bit like putting a layer of royal icing over a cake. Of course, this being glass and occasionally having a mind of its own, you might well find that there's now too much clear glass and you end up with a clear ring going all around the cab! Plus don't forget that where you actually put your cab in the kiln will make a difference to the temperature (again, like baking in an oven - you need to find where it's hottest). Good luck! Also, btw, if you end up with a load of small cabs that are not quite what you would like but are 'ok', then you might consider selling them in small batches on eBay, unless you have plans for them yourself.

galanthus said...

Your jewellery looks lovely, but to be honest, your writing is so entertaining, you shld try your hand at a book, so funny.

Very interesting tutorial, you've made my mind up about getting my kiln today :D Thank you.

by Susan Ruvolo said...

Hello! Thank you so much for this interesting article and your wonderful replies to people's comments. I have been fusing dichroic glass for about 8 months now. My cabs always come out square and often with very pointy corners. I have asked a few friends that also fuse as well as the shop where I purchased my kiln. No one has been able to give me an answer. I have been googling this problem for some time. I was so happy to come upon your suggestions. I can't wait to go try and see if this fixes my problem. Thank you again!