Thursday, 23 July 2009

Ask Me : Encasing & Cracking Problems

Hi Laura,

Whenever I try and encase, nine times out of ten, my bead cracks. I have to let my beads cool in a fibre blanket through the night. I have a small silver clay kiln and I hang my beads on chopped up mandrels on a little home made shelf and batch anneal them. More tend to break after annealing. Any thoughts on what I'm doing wrong?

Much love
Bev x

Hi Bev,

This is a really common question. Most people start out beadmaking with the whole fibre-blanket-or-vermiculite-then-batch-anneal thing. I did the exact same thing. And I had the exact same problem. I could make smallish un-cased beads and they would cool with no problems at all. The minute I tried my hand at encasing was when I started getting beads cracking.

I'd read a lot about clear glass and all the different ones available and I was fished in by the lure of Lauscha's crystal clear sparkliness and decided to give it a whirl. I'd received Passing The Flame as a Christmas pressie and I was eager to try out one of Corina's spacey cosmic beads. I did so and cased my Effetre with Lauscha and the three beads I made were good when they went into the warm vermiculite. They were good when they came out too! But I was wary about the compatibility issue that surrounds mixing glasses of slightly different COEs so I did my Kitchen Windowsill Test. This is a very technical test where I place beads on the tiled kitchen windowsill for a couple of days. The windowsill gets sun and shade and therefore, different temperatures. Two days after making the beads I was stood washing up and I heard a 'ping' noise and I noticed that one of the beads had broken. The next morning the other two had also cracked. I looked at the cracks and after a spot of interwebs research I concluded that it was more likely to be a thermal shock issue rather than a compatibility one.

That was the point where I decided to buy a kiln that I could put my beads straight into as I made them.

In my highly unscientifically-minded opinion, I just think that encased beads are fussy things that like to be kept warm. They feel the cold, poor things, and even though you've swathed them in a coat of hot, clear glass they're still chilly underneath and that is where, I think, the crux of the problem lies.

While I was waiting for my kiln to arrive (from America as back in the day you just couldn't get a beadmaking kiln in the UK) I carried on with the vermiculite and I tried my hand at more encasing, this time using Vetrofond clear. I kept my encased beads quite small but they were still cracking. So I left the encasing and concentrated on other stuff.

When I eventually got my kiln and garaged my beads straight from the flame all of my bead-cracking problems magically disappeared.

My advice to new beadmakers is to do the vermiculite-or-fibre-blanket thing but I tell them to expect cracks if they encase. You get to practice basic beadmaking this way but to be honest, if you're at the encasing stage then you really should be thinking about putting hot beads into a hot kiln. This saves time, glass, stress and disappointment. Yes, a kiln is expensive but it is an absolute necessity if you intend to pass your beads on to anybody else, be it as a gift or by way of selling them. Aunt Beryl would be very upset if you gave her a nice bead necklace for Christmas but come New Year the beads had cracked and fallen apart. So yep, in my opinion, encased, elaborate, sculptural and large beads need to go straight into a waiting kiln.

But don't let this put you off batch annealing. Un-cased beads seem to survive very well and there is so much you can learn and practice with them - dots, stringer, shaping and so on.

I think I'd also better address the whole glass compatibility thing a bit more here. As I said, I got cracking problems when I mixed Lauscha with Effetre and even though I'm 99% positive it was thermal shock, I've never mixed those two glasses since. That is my personal choice. I know many beadmakers that successfully use Lauscha with Effetre with no problem at all. I don't use the two together because I just don't. Have I stressed enough that this is my personal choice? I'm not decrying anyone for mixing the two and I'm not saying it's wrong. OK?! ;o)

Right. Hopefully that answers your question, Bev. Hot encased beads really do need to go into a hot kiln. To do this your kiln will need a digital controller and thermostat. Just a ramp-up, ramp-down kiln isn't enough. You need one that will sit at a garaging temperature for however long you want, then anneal for at least an hour, then ramp down. I have a Paragon SC2 with bead door and it does the job lovely.

Hope this helps. Happy encasing!

Laura x

Got a lampworky question? Email me at ask@beadsbylaura.co.uk and I'll do my best to answer it for you!

Please Note : Any answers and advice I give here are based entirely on my own lampworking experience and are my own thoughts and opinions. All views stated are personal ones and should not be taken to be carved-in-stone recommendations of what to do and what not to do with regard to beadmaking.

5 Comments

hellomyflumps said...

Thank you Laura - that's a great help - i best start collecting those pennies :-) xx
Bev xx

Laura said...

No worries Bev. Glad I could be of help!

Sue Doran said...

I have encountered no problems encasing Effetre with Vetrofond clear glass. However, I have found some colours in the CIM range crack with Vetrofond encasing, even using a kiln and despite being of the same COE. I now don't encase CIM glass at all.

My equivalent of the window sill test is to put my beads in the freezer for a couple of hours (in a plastic bag, just in case!)

Laura said...

Sue - yep, I use Vetrofond clear for all my encasing. It's basically the same glass as Effetre.

I've cased lots of CiM colours with Vetrofond with no problems at all - just goes to prove what I said about the Lauscha and Effetre thing. Some people can and do, and some people don't. And that is what makes all us beadmakers unique!

hellomyflumps said...

i think i will be trying the window and freezer test for alot of my beads as they seem like very good ideas .. :-) thanks !!xx