Why do my lentils split

[wendy j]

I treated myself to a medium lentil press from Marin at the essex bead fair on Sunday, and when I got home I had a play.  One plain lentil and 3 decorated ones, one with stringer and 2 with swirled dots.  This morning when they came out of the vermiculite only the plain one survived removal from the mandrel.   I have been having this problem with the lentil trio press I got from some one on here but thought the extra depth of a larger press might help stop the splitting.  Im reheating the bead after decoration, perhaps not long enough?  Any suggestions?
Thanks
Wendy in Essex

[Lush!]

What kind of glass are you using?

Are you spending a long time gazing in admiration at your bead before putting it in the vermic?

[Lush!]

Part two ... 

What have you got your vermiculite in?

Is it deep enough?

Have you tried warming it in a slow cooker?

[Jolene]

Also the brass press chills the glass quickly. Are you warming the whole bead through thoroughly again before popping it in the vermiculite?

[Pam]

It'll be the way you have cooled them I'm afraid.
As Jolene says give it a good warm to get rid of the chill markes and the flame anneal in the cooler part of the flame (for quite a while ) before putting in the vermiculite.

I must admit this is why I stopped using vermiculite, it takes so long to falme anneal pressed beads and certain transparent glasses still crack.

[Mand]

Hi,

I've had  a lot of my lentils splitting too. I've started using my slow cooker to keep the vermic warm which has helped with beads not cracking.  Out of interest how long would you say a flame annealing of a medium lentil bead should take? I've not tried doing this before as I cool in vermic, then batch anneal.

[Mary]

Pressed beads are less likely to survive flame annealing and vermiculite, because their shape means they cool unevenly. And once they get bigger it's worse, the centre holds more heat so the temperature difference from core to surface is greater. Either stay small and round, or get used to losing a percentage, I'm afraid.

[Mand]

So should they go straight into a garaging temp in the kiln then?   I really want to make a set of lentils but have got as far as three...

[Mary]

I used to just accept that some break, and make extra! But yes, garaging makes a big difference, well, it did for me.

[princess pink]

i found i've lost fewer by flame annealing and sticking into a fibre blanket, had so many crack in vermiculite but a fibre blanket seems to do the job. i do tend to re-heat in the flame and flame anneal though, and i don't tend to repress more than twice on average.

shahlaa x