Bead Cracked, help me figure out why?

[Olimpia]

Hello,
I think I might know why this happened but I am trying to understand and would like to double check with all you guys.

Large barrel of 428 Morretti, (it's a red from an assortment, is this Coral) rolled lightly in Pshyche, encased with Lauscha reformulated.

I garage at 950, Anneal for 1 hour at 968, ramp down slowly to 848, then turn off.

There is a crack from hole to hole.

Things I think might have happened:
-428 is one of those colors that don't like to be encased?
-Didn't warm up my bead fully before putting in kiln?
-Admired bead too long? (although I've been having sticking beads lately so I guess I've been putting them in too hot)
-My schedule is off?

See? I have searched the forum for answers but I found too many options.

Thank you so much!!

BTW, should I anneal Psyche at a different temp? Seems like the colors looked a lot nicer when they went in.

[beadlvr]

I'm not sure what happened but in my annealing schedule I garage at 960 ramp down to 850 or 860 (can't remember), hold there for an hour (might be less because it was set up a couple of years ago and I can't remember) but I do hold there for a while, and then slowly ramp down. I don't turn mine off until it reaches 400 or so.

[KEW]

The strain point of Moretti, as I recall, is 820 deg., and you need to continue the slow ramp to about 600 deg. (Although in an emergency, I have been known to turn off the kiln at 700deg.)

Hole to hole cracks are generally thermal. (Although, I admit that I wouldn't totally rule out the whole combo you were using.)

Is your kiln brick?

[Olimpia]

Thank you Sherry and Kew.
Could you dummy down a schedule for Moretti for me?
(something like Step 1 RA to 950 hold for 8 hours,
Step 2 RA to 968 hold for 1 hour
etc... :)[-o<

My kiln is pretty new, it's a Jen Ken brick kiln, the AF3P/11.

Thank you!

[Carolyn M]

I have had some cracking when encasing corals.

[Olimpia]

Hi Carolyn
That's what I've been reading, but didn't know if this is considered a Coral, I am painfuly new lol.
I have been garaging and annealing using this schedule since I started making beads, I would think a couple of hundred have survived, only this one has cracked. Although, who knows down the line huh?

[Toni Lutman]

Coral is definitely a color that doesn't like to be encased (along with the special colors, such as reds, yellows, oranges and browns).

To get around this, make a clear core, and cover it with your color, then decorate and encase.

[jaci]

428 is Light Reddish Orange. I imagine that it would react in the same way that coral does, it is very close, and is a special color. Hole to hole sounds more thermal. Maybe it was a factor of size colors and kiln??? don't you love it when glass is an exact science... :rolleyes: :lol:

[Olimpia]

lol this is going to be harder than I thought... lots of trial by error huh?

Should I modify my schedule, I took this one from a thread, not sure if it was WC maybe...

[jaci]

yes. you need to cool slowly until the strain point has been passed. 700 is safe. try about 50 degrees every hour until you hit 650, then you can turn it off. if you search there are many different schedules. just go slow. (kilns are not my speciality... lol)

[beadgoodies]

You turn your kiln off at 848? If I remember correctly, that's a strain point for 104 glass. Some people even soak for a time at that temp. I don't schedule my kiln to turn off until it hits 400. You may not need to go as low, but I would definitely go lower than 848 -- especially if you're making beads that are on the large side. Just my opinion, of course!

The type of cracking you describe is definitely a thermal shock type crack. Maybe you waited too long to put it in the kiln?

Candy