Ok, so it took me longer than planned to get things together for this tutorial but I finally made it as promised. Remember, there are lots of ways to accomplish the same thing and I've presented just my own methods here. I'm certainly not the foremost authority on bead slumping!
What you need:
1) kiln which will fire to at least 1350 degree F.
2) kiln shelf & wash or fiber paper
3) beads to slump
4) a timer is helpful (esp. if you are the type to burn cookies)
I prefer to slump all my small glass on 6" kiln shelves that have been coated with kilnwash. You can use watered down bead release. Apply with a soft brush until you have a good coating, usually 5-6 layers. I prefer Bullseye brand kilnwash over the others I've tried so far. Below is a picture of the shelf before it's been used and one that I have already fired glass on. See how the color changes? You can usually use a shelf several times before you must reapply the kilnwash. Be SURE to wear a dustmask when you scrape off old kilnwash (dry) and reapply.
Another option is to use fiber paper on your shelf instead of wash. OR you can use THICK fiber paper (see below) instead of a shelf all together for small things. Kilnwash tends to give a smoother backing to your fired pieces, so I prefer it, but fiber paper is perfectly servicable and I've used it as well.
I intentionally crack beads that I plan to make into cabs by leaving them to cool too long before putting into the kiln. Sometimes I crack them unintentionally too! There are plenty of ways to split your beads, from saws to hammers. I find I can split beads pretty well using a flathead hammer, metal punch slightly (fractionally) larger than the bead hole and a solid base such as a metal block. Lightly tap until you have split the bead.
Be very sure to clean out any remaining release you have in the bead. Bead release left inside a bead will bubble up and cause your cab to be quite ugly, depending upon how much you have and how long you fire your glass. It's best if you get rid of it!
Place your beads split side down on the shelf/fiber paper. If you are slumping whole beads remember the side that is up will be the 'good' side, the side that is down will go against the skin or cab setting, so position accordingly. If you are using whole beads like bicones it is sometimes easier to set the kilnshelf in the kiln and load it there because these babies tend to roll. I've made different beads for this tutorial so you can see what happens when they slump.
Load the kiln. Be sure nothing is touching the elements and there is plenty of room for each bead to spread as it slumps.
I'm using an Evenheat Hotbox Kiln. I've used both of my other kilns (see below), and Evenheat 2541 and a Glasshive custom annealer for slumping, but the little hotbox is a super investment if you plan to slump small pieces regularly. It's very affordable and easy to use. There are plenty of other good small kilns out there too.
Glasshive custom annealer (it's purple!)
Evenheat 2541 with several greenware slumping molds drying on top
Starting from room temperature I ramp up the small kiln (hot box) using the following schedule for small beads:
15 minutes on Medium (heats up to about 500 degrees)
15 minutes on Level 5 (heats up to about 1000 degrees)
15-30 minutes on High (heats up to around 1500 degrees - I watch until I have the slump shape that I want)
Flash cool down to between 1000-1100 degrees (vent the kiln to do this - you should have thick gloves on, preferably kevlar).
Soak for whatever your preferred annealing cycle is down to room temperature again.
I like my cabs fairly flat for use as pendants or ring settings so this cycle works great for me. You can slump a bead as low as around 1350 pretty effectively, it just takes longer. Slumping at higher temperatures means you have to watch very closely because the glass can move from bead to puddle very quickly. If you wanted your cabs to be more bumped up (hump shaped) then I'd recommend a slower, lower temp slump which you watch until you get the feel of it.
I'll post the flattened cabs once they finish in the kiln.