Boro with Quartz Kiln Schedule Question

[Dammond Taylor Studios]

what up all? does anyone have experience with firing boro pendants with quartz encased? what does the kiln schedule need to be?

i've been making small pendants with Herkimer diamonds which are really fine quality quartz. basically a tube encasement, color backing, loop, nothing crazy. the pieces of quartz are small, less than the size of a pinky fingernail. they retain there clarity until i put them in the kiln and run a cycle. i've been running the kiln to hold at 1050 for 8hrs, ramp to 1200 for 1hr, down to 1050 for 1hr, down to 900 for 1 hr, off to cool overnight. when the pendants come out the quarts has lost its clarity and looks like it has exploded somewhat, milky white instead of clear. Basically Im trying to figure out what the kiln schedule has to be. as i understand, the quartz strain point is 2000 F. a lot higher than the boro.

right now, i'm leaning towards holding the kiln at something like 1200 and then ramp to near slumping and cool really slow.

what do ya'll think?

[andrew brown]

Im not sure why you are trying to hold at 1200. Glass will sag, get marks, and move at 1200 especially for an hour. With the ramp towards slumping temps (1890- to over 1900 and upwards of 2100 for casting) most kilns take hours to get that high. During the 1300 to upper 1400's the glass starts to devitrify. I think if you went this route you would have a slumped hazy lump with a cracked herk in the middle.
The only successful pieces with herkimer's that I have seen have been hollow with the piece in the middle, or attached with epoxy. I think the problem is with the coe of the herk and not the annealing schedule.
Hope this helps.
Andrew-b

[Dammond Taylor Studios]

i'm worried about the kiln schedule b/c the herks dont exploded/become cloudy until after i'm done working them and they're in the kiln.

check out this link. this is why i think higher temps and slower cooling might work to keep the herk from exlpoding.

hXXp://online.momentivequartz.com/en/pdfs/annealing.pdf

has anyone seen encased herks that aren't exploded and cloudy?

[BlueBeard]

yeah the crystal cant be "melted" into the glass because of the different coe. A friend of mine makes small hollow pendants with herkimer diamonds in them and she just runs it like she would any other bead. the herkimers do still crack in the oven but the usually stay in one piece and are usually clear still. She has done several different types of stones this way andhad success.

[Mecha]

Herks are not the same thing as the quartz in that pdf, so that info is not relevant.