View Full Version : Breaking beads
07-20-2006, 12:57 PM
I'm new to the Lampwork world and have only 30 hours or so into it. I've recently purchased my tools including Minor burner, Propane, Oxygen concentrator and Kiln. I've made 50 or so beads using Morreti glass with half of my batch breaking when I'm removing them from the mandrel or cleaning them. They are clean breaks mostly breaking in half or three pieces. They are kiln annealed at 950 degrees for approx. 3 1/2 to 4 hours. What am I doing wrong?
07-20-2006, 01:24 PM
Can you post your full annealing schedule - it would be easier to see what the problem is:)
If you are just soaking your beads at 950 but never slowly ramping down your temperature then that would be your problem.
07-20-2006, 01:32 PM
I've had the same problem in the beginning. I found out that it was not an annealing problem. (I still don't have a kiln). But one moment I saw, my beadseparator was not sticking to the mandrel. Since I changed the separator, none of my beads are broken.
Which separator are you using?
07-20-2006, 05:22 PM
How quickly are you getting your beads from torch to kiln? If your torch is on one side of the room and your kiln is several feet away, or even across the room, that could be the problem. Learning to know when to put a bead into the torch takes a bit of practice. I read somewhere that you let all the glow go off your bead before you put it into the kiln. I did that and most of the broke the way you discribe, which is indicative of a "stress" fracture (cooling too fast. I now blow on my bead a couple of times, then tap it on the metal door handle. If it make so noise, or is still so molten that you mark your bead, it needs to cool a couple of seconds more. If it makes a nice pinging sound, that means the "skin" is firm enough for the bead to hold it's shape, but the middle is still hot enough to start annealing. Depending on the glass, sometimes I still see the "glow" on the bead when it makes that sound. I find Moretti does best at 960 to 1000 degrees for annealing but Once down to 800 - 850 degrees you can let the kiln cool by itself as at that temp the stresses in the bead are either healed or not healed. The only way to tell for sure is if they crack like yours.
07-20-2006, 07:28 PM
What trappedinabead said...lol... except I only run my Moretti at 960 degrees high
07-20-2006, 11:19 PM
Many thanks to ALL of you :0) :)
I first turn on my Paragon kiln which was pre-set to 950 by Sundance Art Glass who is the supplier that I purchased my goodies. I then turn on my Oxygen concentrator and Propane. I make stringers while waiting for the kiln to reach 950. I then do the usual and melt my glass on to my mandrel that was dipped in "Blue coat" that has been wafted over the flame. Sometimes I leave it in the flame too long and it gets red hot.
I then do my footstep around the mandrel and proceed with my bead. When I start to decorate my bead with my stringer I pull my bead away from the flame so that I can see what I'm doing. It does cool off a bit when I'm decorating and then I put it back in the flame but not so far into the flame that it's so hot that it starts dripping. I keep it in there to make my bead as perfectly round as possible.
Once I'm done I turn around to my kiln on the work bench which is approx. 4-5 feet away and I place my mandrel in the door. I continue this step until I'm done with my mandrels for the day. I usually bump some of the soaking beads when putting in a new one and they drop to the bottom of the kiln and I put them back in their spots to soak. Once I'm done for the day I turn off the kiln and let it cool down.
After 3 1/2 to 4 hours I check the kiln and the beads are cool (maybe a little warm) so I take them out because I AM SO EXCITED to see them!!! :clap:
When I'm taking them off of the mandrel they break in half or they break when I'm cleaning them with my reamer.
I don't know if they are breaking from
1. Single coat of release
2. Red hot mandrel so I burn the release
3. Pull my bead away from the flame too long when working on it
4. Dropping in the kiln
5. Not Annealing at a hot enough temp or not soaking long enough....
Then the next HUGE dilema.... I can't get them off of the Mandrel. They are so stuck that I've ripped my fingers from twisting. I read that you can use them as a plant do da but I like those beads and want them unstuck. They're in the freezer right now with hopes of giving up... : 0)
Thank you all for being so great on my first day with Wet Canvas!
07-21-2006, 02:33 AM
Maybe your annealing temp isn't high enough. Each kiln I've noticed has a 'range' for any given temp. Not kilns work equally. After you make your last bead set your kiln to run for 30 minutes @ 960. Then ramp down to 700 degrees for 45 mins and then turn off and let it come to room temperature. That takes a good 6 hours. Don't take them off the mandrels until they are completely cooled. It might feel cool on the outside but it's still warm on the inside. As for your problem with getting your beads off the mandrel. It could be your bead release. You might want to try Foster Fire. It's both air dry as well as flamed dried. I've had no problem with beads breaking following the above mentioned info. The only time I have something crack is if it's too thin. Hope this helps
07-21-2006, 06:32 AM
Sounds to me as if it could be one of two things or a combination of both. First, your kiln needs to be closer to you. Especially if you have and ac going in the room that trip to the kiln could be cooling the bead too much too quick. And the temp of the kiln. You say your supplier preset the kiln? I am not sure how that is done, but from experience, some Moretti glasses take more than 950, particularly the ones with lots of metal in them. Your bead is probably stuck onto the mandrel because some where along the way the bead release fell away from the bead and now the glass in melted to the mandrel. If that is the case, the only way to remove it is with a hammer. I know next to nothing about the flame dried release, except that I was having the same problem when I first started; add the cost of the bead to the cost of the flame dry release and I figured it was best to make my own release from a receipe that was given right here on wet canvas.
07-21-2006, 11:21 AM
I'll give everyones advise a try
07-21-2006, 11:28 AM
Good beads, by the way....I would not want to give them to the plant gods either! Gina
07-21-2006, 03:06 PM
first of all, VERY pretty beads!!!
If you are going from 950 to touchably warm in 3 1/2-4 hours, I think that is too fast. It's possible I am too careful with my annealing, but I soak at about 1000F for 45 minutes (give or take depending on the size of the largest bead), then ramp down to 600F or 700F over the next 2-3 hours (this takes me into the wee hours of the morning; god I want a computer-controlled kiln!). This is for moretti/effetre.
As for the bead release, I purposely let mine get red-hot for a bit before I start winding. Does your brand have instructions not to? I use Alice's and have VERY RARELY had a problem. I do a quick double-dip and that is that. Every other release I have tried, I have had the sticking problem. If I have to flame dry, I do it very slowly starting in the top of the flame, watching til it stops steaming, then inroduce it lower into the flame. I don't think Alice's is meant to be flame-dried, so I try to remember to dip in advance. One good thing about the hot weather is that it doesn't take very long to air-dry.
I have a question for those who might know~~ If I spend 2 hours making beads, is that a 2-hour soak for the first bead I put in? Or does the temp inside the kiln fluctuate significantly from opening and closing the door that any annealing that has taken place is negated? I'm wondering if I could make large beads at the start of a session, and gradually get smaller and still get away with a 30-45 minute soak afterwards? as long as the ramp-down is nice and slow...
But don't let me hijack the thread...
07-21-2006, 08:56 PM
Hey, there, Supperman!! Your idea sounds fine. All kilns, even those of the same brand have thier own little idiosincrosies so a lot of your annealing process is going to depend on how well you know your kiln. Mine is digitally controlled...and the digits are attatched to my palm. One thing that is constant about any kiln, the more you put in it, the better it retains the heat. Opening and closing the door should not be a problem if you are doing it quickly. Obviously, it is not a refrigerator; you can't stand in front of the open door and expect to see something in there that was not there the last time you looked or it will loose a bunch of heat. Y'know, I don't even know what brand my kiln is...I bought it from Whale Apperatus almost 6 years ago and it is metal clad. The whole front of the kiln opens to allow access. When I am finished with a beading session; anywhere from 1 to 12 hours at a time, I just turn the kiln off and walk away (it is usually way, way past any sane persons bedtime) and leave it to cool all night. In the morning I retrieve my beads. Haven't had a problem so far (knocking on wood).
vBulletin® v3.5.8, Copyright ©2000-2014, Jelsoft Enterprises Ltd.