Pegasus oval bead roller

senge · September 25, 2011, 07:01:31 PM

Help, I wanted to get a donut bead press with the centre hole but decided this would be too tricky for me at the moment. So I went for the Pegasus oval roller, my first ever roller. Well I am very pleased with how they come out but I am doing something very wrong. The largest oval I have pressed to make a flat pendant they( I have tried 4 )look lovely for a few minutes then they stress crack. I have a hot head torch and use the bubbles to cool slowly the next size down works lovely (so far ) . Each of the large beads I pressed to a different thickness in case that was the problem, do you think the centre of the bead gets too cool in the making as they take me and age.
Any help appreciated
Senge

Madam Steph · September 25, 2011, 07:09:42 PM

After pressing, do you flame polish (or reheat somewhat)?
Sadly it may be the size of the bead.
If you keep the bubbles hot in a slo-cooker, it may increase your chances of keeping them intact as they will cool slower.
Just a suggestion. It's what I used to do prior to kiln

Josephine · September 25, 2011, 07:17:03 PM

Pressed beads are much more prone to cracking when batch annealed than non pressed. Maybe try not pressing as thinly and make sure you give it a good reheat at the outer end of the flame, just keep turning one side to the other so it doesn't heat enough to go out of shape, and concentrate on the line that runs along the mandrel as that is the area of most stress.

senge · September 25, 2011, 07:46:27 PM

Thanks for the prompt replies ,
I heat the bubbles Over 3 nightlights and the last one I made I left the night lights to burn out. I also reheat the beads after pressing to remove the pressing marks , I have pressed each one thicker than the last, I will try an oval bead without pressing to see see if I can get it to stay hole.
Senge

senge · September 30, 2011, 01:43:20 PM

I decided to make all the different sizes on my bead roller.
I have by not had time till this morning to clean the last two
The two largest ones, they had been left in water because I was
going to clean them but ran out of time.
They both were fine I cleaned the holes and 10 minutes later the biggest one had cracked.
I do not know why , I thought pressing the largest bead was the problem
but it cannot be that so I must be at fault in the making or cooling.
Any hints as to what I am doing wrong.
Senge

MadelineBunyan · September 30, 2011, 02:27:33 PM

oh how annoying!

I have that roller, I'll try making the biggest one and sticking it in the bubbles and see if its just the size. I used to find there was a size limit with beads that didnt go straight in the kiln.
might not be today though, got lots to do!

senge · September 30, 2011, 04:20:50 PM

Thank you Madeline ,
At least if you try one I will know if it's the size or the maker
thank you in advance for trying
Senge

Josephine · September 30, 2011, 04:39:01 PM

I would guess that it is to do with size. Just thinking about it logically, the centre of the bead is going to stay hot longer than the outside so the temperature difference in a big bead is going to be greater as the centre will take longer to cool than it would in a smaller bead where the whole thing will cool relatively much more quickly.

MadelineBunyan · September 30, 2011, 04:40:19 PM

Thats more or less what I think Josephine, but I'll attempt to prove it! (in a thoroughly un-scientific, yes it breaks, kinda way!)

MadelineBunyan · October 01, 2011, 06:14:45 PM

right, I have made two biggest size ovals
after I made the first I realised opaque green was a really stupid choice as I won't be able to see any stresses! so I made a clear one and slapped some 104 frit on it.

I will clean them and keep an eye on them and see if they break anytime soon. off to get the clear one out of the bubbles now.
I made them as I normally would, just make the bead, heat it through pretty well at the end, let it cool to not quite lost all its glow as its so big, only needs the surface to not be sticky really, and into cold bubbles.

sarah t · October 01, 2011, 06:31:50 PM

the roller will take nearly all the heat out of your bead and then the squish will do the same ~ make sure you heat the bead back up all the way through not just the outside before you squish, then when you squish try not to do to thin then re heat again to the core again...i think the problem is not getting the heat back into the core of the bead before you put into the bubbles ...larger beads are a bugger to stop cracking if you are not garaging in a kiln

MadelineBunyan · October 01, 2011, 08:32:59 PM

I was wondering as I made them how hard it is to get the heat back into a bead using a hothead, being as I've not worked extensively on one, wondering if that was a contributing factor. maybe it is patience that is the difficult thing. I would struggle!

senge · October 01, 2011, 10:06:09 PM

Thank you Madeline, on my hot head it takes me ages to make the largest one.If yours survive it has to be the way I finish my bead , sounds as if I am not reheating the bead enough.I will wait to see how yours come out , then I will try again.
Senge

senge · October 10, 2011, 10:13:14 AM

Well I think I might have cracked it . I changed to a different glass and when I finished the bead I played it in and out of the flame for longer than before and after 3 days it's still ok. I made another one in the same glass and did exactly the same and after 1 day it's ok , so I thought I would test it . I poured boiling water over It and left it to cool in the water . The reasoning for doing this was it was opaque glass and I thought it might have a hidden crack and I read about doing this in my Warm glass book.
Thanks for helping
Senge

MadelineBunyan · October 10, 2011, 10:37:06 AM

just checked, both of mine are still intact.
glad to hear you're having more success now!