No, I'm not about to burst into song - for one thing I'm struggling to find a bead-relevant rhyme - but I thought I'd just write a few words on what a 'yesterbead' is, and, more importantly, why.
'Yesterbeads' are, quite simply, beads that I made yesterday. So far, so obvious! Although the making of a single glass bead, depending of course on complexity, is a fairly short and direct process, I don't get to play with that bead immediately. Why? Because it needs annealing.
Items made out of hot glass need to be annealed for lasting strength. Annealing happens in an annealing oven, or a kiln, or in the case of factory-made drinking glasses, for instance, on a very long, slow conveyor belt. Small things like beads don't take all that long to anneal, but larger things - well, how long is a piece of string? Vast glass items such as massive space-telescope lenses, for instance, require annealing over the course of many years.
What is annealing? I'm going to explain my own understanding of the process, using my lampwork glass beads as an example.
Heating and manipulating glass adds stress to the glass. If the glass is cooled too quickly, that stress has no means of relief, leading to weak points and cracking.
Glass expands when it's hot. A molten bead in the torch flame is larger than a cool bead sitting on the workbench. If a hot bead cools too quickly, it could very easily crack - and the way I see it is that because cooling happens from the outside inwards, the bead's outer surface is cooling (and therefore contracting) faster than its still-hot, still-bigger, innards. It's as if you're trying to imprison something in a cage that is smaller than the captive! That's not going to work, right?
The fact that glass expands when it's being heated, and contracts as it cools, builds up layers of stress. These layers of stress can - and do - result in cracking, which can happen either immediately, or many days, weeks or months down the line, when the glass is exposed to extremes of temperature, for instance.
Annealing is the secret weapon to ensure lasting strength of a lampwork glass bead!
My everyday working practice is to put each bead in turn, as I make it, into a preheated kiln, where it sits at the correct annealing temperature until an hour after I have made my last bead of the day. The molecules remain at this 'happy' temperature until such time as I ramp my kiln down to begin the very controlled cooling process. I cool my beads at a rate of 60 degrees fall in temperature per hour, which given the scale of my work (they're beads - they're little!) means that every part of every bead spends consistent time at consistent temperatures all the way through - and beyond - the strain point of the glass.
Beads I make on a Tuesday are ones which I take out of the kiln on a Wednesday, when they are safely annealed and have reached room temperature. At that point I carefully remove them from their mandrels, file the holes clear of bead release residue, and have fun putting them into size-ordered sets.
I remember speaking to a jewellery maker some years ago who was delighted with a recent online purchase of lampwork beads from the Far East. 'I bought a set of five, and the seller sent me ten! I was delighted! She'd sent the extra five to make up for the inevitable breakages in transit - but only three had broken, so I was two up on the deal!'
The seller knew that the beads would break. What a shame! Unannealed beads subjected to extremes of temperature (for instance, in the hold of an aircraft over many hours in an airmail envelope) can, do and will break.
I like to give my beads the best chance possible of survival, and anneal my work straight from the torch flame. That's why the beads I show you are always beads I made the day before.