Sunday, October 30, 2011

Misadventures in annealing...

Last time I blogged I wrote about the Devardi Professional Mini Bead Annealer I ordered.  USPS took their sweet time delivering it, but when the box finally arrived I took the annealer out, plugged it in, and spent the next couple weeks annealing dozens of beads I've made over the last few years.  You don't know how good it feels to be able to anneal my beads after having hundreds of unannealed mini time bombs sitting around my house in bowls, ziploc bags, and rubbermade tubs for so long.

Devardi Mini Bead Annealer at work!

The first couple batches I ran were test runs, figuring out the right batch annealing schedule, and with the awesome help of several of my friends on Lampwork Etc. (A huge "Thank You!" to GlassGalore, periwinkle, Holly, Anne, Dragonharper, Lisi and PittsGlass!) I was able to refine a schedule that worked for me.  After my third batch, my trusty polariscope (aka polarimeter) showed my beads were annealing and I was happy as a clam.

This is the batch annealing schedule I finally settled on:
0 to 950 over 2 hours

Hold at 950 for 1 hour
950 to 840 over 1 hour
840 to 600 over 1 hour
600 to 300 over 1 hour
Turn off annealer

Here is the difference between unannealed and annealed beads as seen through a polariscope:
Unannealed Beads
Annealed Beads
The next couple batches came out perfect, then there was trouble...
The distinct line between rough ick and glassy beauty.
Suddenly about a quarter of the beads that came out of the next three batches had rough patches on the sides, next to the bead hole.  I hadn't made any changes to the way I was annealing the beads, and the colors were a random mix as they had been the first few batches, so I couldn't figure out what was going wrong.  I also knew it wasn't the temperature of the annealer, cause I had a pyrometer to keep track of the temp.  At this point I was pulling my hair out.  I hadn't spent all that money, time, and electricity trying to get my beads annealed just to end up with ruined beads.

Someone on Lampwork Etc. suggested it might be my non-stainless steel mandrels creating an icky atmosphere in the annealer.  I admit, my mandrels were old, ugly with firescale and rust, and so I latched onto that theory like a drowning man to a life preserver.  I sanded my mandrels to a sparkling steely shine on our belt sander and my next batch had no more of the ugly patches.  I did run that batch with some of the previously damaged beads, but they came out as bad as before.  I have no idea how I'm going to fix it, but someone suggested bringing them back up to temp in the annealer then flashing them through the flame of my torch.  I'll try that next time I run a batch.  For now I'm just going to make beads and put them into the hot annealer.

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