View Full Interactive Version Of This Page : Help with cracked lampwork beads.
Can anyone give me advice as to why some of my lampwork beads (mostly larger ones) are cracking days and sometimes a week or more after they've come from the kiln.
It is very upsetting to have a beautiful bead ready to sell and then you go to list it or already have pictures of it in perfect condition and then find it cracked.
I guess the most difficult to understand is why it is cracking days and weeks later.
HELP!::sad:
most likely thermal cracks - how are they cracking?
HI-well they are just cracking anywhere on the bead.
Why would it take so long to crack? And what does thermal crack really mean?
spider web type cracks or cracked in half?
WEll I guess they would be spider web type of cracks because they aren't broken in half.
do you have any pics?
What specific glasses are you using?
I'm using soft glass.Also double helix,dicohric,silver mesh,copper mesh and occasionally silver wire.
theglasszone
2010-03-12, 7:21pm
Are you encasing in clear? Some clears do not play well with the silver glasses...pictures would be so helpful.
De
How do I send pictures? I'm fairly new on this site as you probably can tell.
likes to make glass stuff
2010-03-12, 7:59pm
do you anneal your beads in a kiln?
Yes I am using a kiln with a temp of approx 990 degrees f.
likes to make glass stuff
2010-03-12, 8:11pm
What is your annealing schedule? How long does it sit at each temp, and how fast does it drop in temperature?
houptdavid
2010-03-12, 8:13pm
The max temp doesn't matter as much as the strain point.
Pics... go advanced...image uploader
Okay I now feel really dumb but oh so glad I have come here for help.
What does the strain point mean?
Sounds like the clear to me. Which clear are you using? You might want to switch to Double Helix Aether or the Lauscha Soft Clear.
I'm using Lauscha soft clear.
Karen Hardy
2010-03-12, 8:43pm
I'm using Lauscha soft clear.
Bingo.
houptdavid
2010-03-12, 8:49pm
I'm using Lauscha soft clear.
Thats the problem! Lauscha clear doesnt play nice
Strain point...
http://www.arrowsprings.com/html/annealing.html
Really? And it isn't cheap.
What should I do?
I have had a terrible time with other clears being cloudy and what have you (such as super clear v005 and v006).
Please recommend a good clear.
I paid something like $30.00 a pound for the lauscha.
Aether - but it's pricey.
Can you give me a site to purchase please?
http://www.doublehelixglassworks.com/
The seconds are good enough for first quality beads.
GlassGalore
2010-03-12, 9:10pm
Before you run off and invest in an $60/ lb. clear, I would do some more analysis and testing! Do you ever have beads do this cracking which aren't encased in clear? If you never make those kind of beads, I'd recommend making some just the same as you usually do, without encasing with the Lauscha, and see how those hold up after a couple weeks. If none of them crack, then it's probably the clear. If they DO crack, then something else is going on.
When did you start getting these cracking beads? You don't say how long you've been making beads, or if anything else happened to coincide with the cracks starting... New kiln? New lot of Lauscha? New lot of some other glass you use in your designs? Possibility of mixing up a different COE with your 104?
Just throwing out some other possibilities, since switching to Aether is big $$! ;)
Thank you.
I'm still curious as to why it took days and sometimes weeks for the bead to crack.
I've been beading for about 2 and 1/2 years now.
Same kiln.
I guess I should try without the clear and see.
Thanks,
I'm so frustrated. Spending so much time on one bead and it turns out gorgeous and then have it crack later on.
GlassGalore
2010-03-12, 9:21pm
Thank you.
I'm still curious as to why it took days and sometimes weeks for the bead to crack.
It's an indication that there was still 'stress' in the glass, which is what proper annealing and using compatible COE glass is supposed to minimize / prevent. If the stress was great enough, you'd see the bead broken apart when you open the kiln door. When there's less stress in the glass, it is still unstable but may take a few days or even weeks to finally succumb to it and crack. So that's why we're asking about the glasses you're using and the annealing schedule you run. ;)
<snip>...I'm so frustrated. Spending so much time on one bead and it turns out gorgeous and then have it crack later on.
I know what you mean. :( Hopefully we can help you find the cause so this won't keep happening.
Another thought... You say that it's mainly the larger beads that this is happening to? Have you always made beads this 'large' and not had the cracking problem before? I'm asking because the larger / thicker a bead is, the longer it needs to 'soak' at the annealing temp. If you're not holding long enough or ar ramping down too quickly, it would cause more problems with the larger beads.
It would be great if you could write up your annealing schedule for us to look over. ;)
I have a "Aim" kiln.
Could you please tell me what temps and length of time for each segment you use.
I must say that I don't think I've had broken beads that weren't encased.
But I love the look of encasing so I want to adjust my kiln just in case it is improper annealing.
I live in a smaller area where there aren't any bead places I can go to in person.
Carolyn M
2010-03-13, 10:15pm
Honestly, I've never had any luck encasing with Lauscha whatever annealing schedule I use, especially when I've been using silver glass.
I would recommend you switch clears. I have tried CIM, it is OK, Diamond Clear can be amazing or depending on the batch, a huge disaster.
midniteburner
2010-03-14, 6:35am
Don't feel bad, I made an entire days worth of encased beads and every damn one of them are cracked! grrr... I don't remember what clear it was that I have but...Worthless crap!!!
Sara
patienthand
2010-03-14, 7:41am
hmmmmmmm think of THE BEAD sort of like the planet earth.. earth has lots of stresses in it becaue the tectonic plates are moving etc, but it doesnt crack all the time.. the stress is sort of stored up and then pop.. it cracks and we have an earth quake when the stress is released.
well if a bead has stress in it, from incompatible glasses, or improper annealing. that stress can also sit there for a while and do nothing for a while, and all of a sudden just let go, and crack.
way back when, when I was testing new colors for my blown work ornaments I would blow multiple ornaments, make notes on a tage and hang them up in the shop and just let em ahang out for about 2 years. If they dodnt crack in that time, I knew the glass was ok to put into production. it was rather common to be sitting and working and hear the dreaded "tink", and you knew something had cracked, and you went and checks the test batches to see what had failed. it was often a year or more before something decided it was gonna "tink".
Working with color can be tricky especially in hollow work and soft glass, because blue might be fine, and pink might be fine, but pink and blue on the same item mgiht crack because the colors dont like eachother. my best sugestion.,, keep notes and change ONE thing at a time. and let stuff hang out longer.. and make sure your annealing schedule is addequate.
Candice
Candice, I love the earthquake analogy. How perfect!
Aryle, your annealing schedule depends a lot on the size beads you make. A popular schedule seems to be cooling at 1 1/2 degrees a minute, or 1 degree a minute. The cooling has to be constant and the beads have to cool at that rate to at least 100 degrees below the strain point recommended by the glass manufacturer, and is approximately 100 degrees below the recommended annealing point.
For instance, if the recommended annealing temp is 950 degrees, (no matter what you actually anneal at) then the strain point will be approximately 850 degrees. However, since kilns are notoriously inaccurate, cooling at 1 degree a minute to 100 degrees below the strain point, or 750 degrees is considered safe. However, that is just to relieve stress built up in your bead when you make it. Below 750 degrees, your bead can still crack from thermal shock if it is cooled too fast, again depending on the size and shape of the bead. Many, many people continue the 1 degree a minute cooling until 400 degrees or even room temperature.
Thermal cracking is due to too fast cooling of the glass and is generally seen as a straight crack running through the bead. Incompatibility cracking or stress cracking is generally described as spiderweb cracking, but that is really a misnomer except in extreme circumstances. If you make a bead of 104 coe glass and then put a big dot of boro on the bead, melt it in, then you will see what is meant by spiderweb cracking. However, when there is only slight incompatibility the result won't be quite so dramatic. You may only see a tiny crack that bends in several directions, following the incompatible glass, or if the glass is all mixed up in the bead, then you may see only a single crack that is relieving the stress in the bead. Sometimes that crack looks like a thermal crack, so it is hard to give an exact answer about the reason for the crack. If the glass is totally cased in an incompatibly glass, there may only be one straight-line crack that relieves that stress, again, looking like a thermal crack. As explained earlier, the earthquake effect, cracking can occur due to thermal or improper annealing or incompatibility, days, weeks or years after the bead is removed from the kiln.
Firebrand Beads
2010-03-17, 4:23pm
I seem to recall reading that Lauscha glasses like to be parked in the kiln hotter than other brands? Still glowing a little?
And just in case, since no one mentioned this, if you are just starting to make bigger beads, do make sure that you have reheated the entire bead to an even temperature before cooling it slightly to put in the kiln. If you spend more time on one end than the other and then park the bead in the kiln, you have parked a bead with uneven heat and that means more stress. FWIW...
vBulletin® v3.7.5, Copyright ©2000-2012, Jelsoft Enterprises Ltd.