Bullseye cracking...

[totallytorched]

I made like a hundred pretty pink and black Paris beads, encased in Schott, and every last one of the buggers craked right in half!! ](*,) What the heck, I annealed , but they were cracked before I annealed them, but fell off the madrel when I tried to remove them. :shock: What did I do wrong?

[suzanne]

Bullseye does not like to cool off quickly. You have to use a differend annealing schedule for bullseye ( I thought annealingtemp is 980 ). You need to put in the bead in the kiln while it is still glowing. Moretti is more forgiving, but bullseye needs a special treatment, try popping them in the kiln sooner.
You might want to visit the bullseye homepage and look up the annealing schedule there.

Suzanne

[pam]

I use 968 for annealing Bullseye, but 980 is fine. Since the beads are cracked in half, it is definitely a cooling problem instead of an incompatibility issue. My guess is either you are letting them get too cool as you work them and they are cracking while you are working on them, or you are letting them cool too much before putting them in the kiln. Make sure as you work Bullseye that you keep the bead warm (warmer than Moretti) and go straight from a reheat in the flame to the kiln. I hope that helps you.
Pam

[totallytorched]

well I am batch annealing, I don't have a bead door. What temp do I need it to be at to just add to the kiln as I am making them, if I don't batch anneal? At 950-960?

[Nanette Marie]

Hi, I use Bullseye a lot and also Moretti, a little Czech, a little Vetrofond, and very little Gaffer. I set my kiln for 975 and I always put my beads in while they are still glowing, and I rarely have cracking issues. I don't recommend batch annealing for Bullseye. 975 is a good average temp for all the types of glass I use. This is what I decided after extensive research on all the annealing schedules for all the types of glass I use.

[totallytorched]

So if I set it at 975, then how long do I soak for? And as I add new beads, how do I ramp down? This process totally confuses me, I feel like...duh!!lol



Jenni

[lunesse]

I use only Bullseye and I keep my kiln at 970 while I work. After the last bead, I let it sit like that about 20-30 min then start the ramp down.

[totallytorched]

I just got a used Jen Ken, small one, and it is a *%$#@ to keep at one temp. I have to keep opening the lid to keep it at 950, is that what I have to do the whole time? And how quickly do you ramp down?
I appreciate all the info, I just want my pretty pink Bullseyes to actually turn out!! :biggrin: I finally find a awesome pink and I can't flippin get it right :cry:

[pam]

Hi Jenni, Does your Jen-Ken kiln have a controller? If so, then you need to decide whether you possibly have it programmed incorrectly or perhaps it is defective. A good controller should be able to hold the kiln temperature within 10 degrees of whatever temp you have it set at.

As far as an annealing cycle goes, it is really pretty simple - just lots of variations you need to decide upon for your beads. First, after your beads have been held at the annealing temp for a certain period of time (most people I know use 1 hour but the general rule is 10 minutes per quarter inch of thickness of your beads) your annealing cycle begins. Your goal is to have the beads all the same temp from the inside of each bead to the outside before you begin annealing cycle. Your kiln should cool at a certain number of degrees an hour until it is below at least 800 degrees. The number of degrees per hour have to do with the type beads you make. I currently use 100 degrees an hour, but I make large beads with different thicknesses. Again, you are attempting to cool the bead slowly enough so that both the inside and the outside cool at the same rate. If you make small beads then perhaps you would want to use a higher number, 200 degrees per hour, for example. You really can't over anneal, so the longer it takes to get to 800 the safer your beads will be.

Once the kiln is below the strain point (which is generally thought to be 100 degrees below the annealing temp), then no more stress can be added to the bead and you can drop your temperature faster. A lot depends on your beads. You can still have thermal shock which will cause your beads to crack, so again, caution is safer than speed. I personally cool my beads at 100 degrees an hour to 400 degrees and then my kiln is shut off and I don't open it until it is at room temp.

Proper annealing is not really complicated, but it is necessary to remove stress from your beads so they don't crack at some future date.
I hope this helps you.
Pam

[totallytorched]

My kiln only has the manual temp controller, it is such a pain in the butt to have to sit there and keep raising the lid to keep it at a temp. I wish I had a digital controller for it that I could program.

Thank you so much for all the info, I am going to try and anneal as I make my beads and see if maybe that will be easier :grin:

[lunesse]

Hey guys, sort of in this thread, might as well not start a new one...
I've been making slightly larger beads and they have been cracking while I clean them. They come out looking fine, room temp, then start cracking neatly while I have a bead reamer in there. I'm trying to be relatively gentle but firm to get the release out. Any ideas?