I'm ready to give up. Help!

[cinder]

A couple months ago, I switched from SC to Zephyr. My encasing improved dramatically as the glass melts so much easier. On the down side, I've never had this many cracked beads or kiln marks. So annoyed.

For the questions that I know are coming, my kiln was set to garage at 980, then down 50º / hour to 700, hold half an hour, then down 200º / hour to 500, hold half an hour, then off. I changed it the other day to garage at 965, then down 50º / hour to 400, hold half an hour, down 200º / hour to 300, then off. thinking maybe that would help with kiln marks. I only had one bead with kiln marks yesterday. I've grown so frustrated with them that I started tapping them with a pick to see if they clink before I put them in the kiln.

I know, kiln rack. I have one, and I use it most of the time because I don't make a bajillion beads a day. I have a bead door on my kiln and getting all those mandrels in there on the rack and through the door without siamese beads... huge PITA- I hate having the rack in there, but not as much as kiln marks.

As for whether they're incompatibility cracks or thermal cracks, I *think* they're incompatibility for a few reasons. I've never had so many cracks before I changed glass. They're usually very prevalent around the holes, not so much in the middle. I never hear or feel that "tink" when one thermal cracks, so they'd have to be doing it in the kiln after I've set them down. I deep heat them, then around the holes and the mandrel before I put them in- especially if I've been admiring the awesomeness. I've had a couple that I thought might be thermal cracks because they kinda run along the mandrel, but the wind around it in a straight line too. I dunno.


Any ideas? Or have I just suddenly lost all basic bead annealing ability? I'm so mad

[AKDesigns]

Zephyr is softer so any beads made with it need to be put in the kiln on a rack while they are still glowing. If you are able to put them in touching other beads and you aren't getting marks then your bead is too cool and will more than likely crack because of it. If you can tap them with a pick before putting them in the kiln they are too cool.

[cinder]

Okay. Thanks

[Toni Lutman]

I have a chili pepper with fiber blanket on the bottom, and I have a small (about 3" wide) little rack in the middle of the kiln.

I make my first bead and put it on the right side of the rack.

When I make my second bead, I put it on the left side of the rack, and by then the first bead has hardened enough that I move it off the right side of the rack, onto the fiber blanket.

Third bead goes on the right side of the rack where the first one had been, and I move the bead from the left side of the rack off to the side onto the fiber blanket.

This way I always have one hot tacky bead on the rack, and a space for my next bead to go.

The ones on the blanket have cooled beyond the tacky stage so are fine if they touch.

[Sherry]

Try putting your beads in glowing, but hold onto the mandrel and keep the bead suspended in mid-air for one minute. It'll seem like forever, but that one minute will allow your bead to firm up safely. Its what I do for implosions.

[ewdb]

This might help:

to avoid kiln marks: after thoroughly reheating the whole bead to orange (hold it under yr table or somewhere dark to see if the glow is consistent) i blow on the bead on all sides to form a "skin", count slowly to 5 (1, 1000, 2, 1000, etc.) and then pop it into the kiln. I keep a fibre blanket on my kiln floor for off-mandrel and really big beads and they sit right on it.

re cracking: if it's mostly vertical or horizontal cracking that usually means thermal. i'd suggest adding a couple soaks to your annealing cycle to even out the heat between all the beads at the various annealing stages - first at your garaging temperature or slightly above and again at around 850F (the approximate/average strain point for Effetre and most other 104 glasses). The length of time would depend on the thickness of your beads and the stiffness (viscosity) of the glass you're using - e.g. i find Lauscha, CIM and 96 COE glass tends to be more stiff and prefers a higher garaging and annealing temp compared to Effetre/Vetrofond.

I rarely ever get any cracking and i mix COES (within the stadard limits) quite a bit in my work. Here are the annealing cycles that i use for 96 & 104COEs - you can adapt them to suit your needs:

- for smaller beads up to 1" thick: garage @ 940F, ramp 350F/hr to 980F, soak for 1.5hrs, ramp down 350F/hr to 870F, soak for 1.5hrs, ramp 350F/hr to 500 and goes off.

- for larger beads and sculptures up to 2" thick: garage @ 965F, ramp 350F/hr to 985F, soak for 2.75hrs, ramp down 350F/hr to 870F, soak for 2.75hrs, ramp 350F/hr to 500, soak again for about 2hrs, and goes off.

note1: Set your annealing schedule based on the thickest bead in the kiln, you can't over anneal a bead. I've heard silver glasses might need lower temps but i just toss them in there and they're fine - then again i don't use them much.

note2: I have a brick kiln, if you have a fibre kiln i'd recommend a slower ramp at each stage since it may not hold the heat as well. I don't take the beads out until they are room temperature.

Hope your next session turns out better!

[cinder]

Thanks all

[Frit Diva]

I was taught that the holding at strain point (870 F) is as important as holding at your actual annealing temperature. With the annealing sched you described, you are not doing a hold time at the strain point, you're skating right past it down to the 700 or even 400 temp. At those temps the strain is pretty much already built in. The sched described by ewdb above sounds very safe, it's similar to what I follow as well. I'd guess that is what's causing your cracking. As far as kiln marks, what everybody already said!

good luck


Jo