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Tips, Techniques, and Questions -- Technical questions or tips |
2013-11-04, 11:28am
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Cracking with XL size focals and Sunburst Coral
Has anyone been having and cracking issues with large focals and Sunburst Coral? I have been having my larger size focals split right down the middle in several designs. The common thing is the coral.
I checked with Glasshive and my annealing cycle is correct.
I called Frantz to see if anyone else had reported problems, but I am the first one to have them. Attached are other photos of breakage. Some are a good deep split down the center and others are teeny hairline cracks that are barely visible.
All of the raku and other glasses are 104 so compatibility shouldn't be an issue. I have been making a point to keep all areas warm and re-heating all over after adding each element.
Ultra fine barely visible surface crack.
Thin surface crack.
Deep split all the way through the bead. Possibly from too many surface changes with shaping, texturing and distressing the glass.
Deep split all the way through the bead. Possibly from too many surface changes with shaping, texturing and distressing the glass. Possible cooling issues with each added element.
Has anyone else had these problems?
xo Genea
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Genea Crivello
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2013-11-04, 12:10pm
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That's why I don't do soda beads in large sizes. It's just too hard to get them back to temp. Top that with temperamental corals like Sunburst and Apricot and .... ooops!
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Julie
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2013-11-04, 12:18pm
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Is the crack on the second bead only on the coral and not on the raku?
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2013-11-04, 12:32pm
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Julie, I have had NO previous problems with baking soda beads before this and I make them ALL the time. I did an XL bead just like this other lentil in a different color and it's totally fine. All of the other smaller beads from spacers to headpins to 1" lentils done like the XL focal are fine. No problems at all. I have never had problems with coral before this batch. So weird!
Hayley- Only on the coral.
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Genea Crivello
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2013-11-04, 12:48pm
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I make XL beads all the time and have never had breakage, but then I've never used that glass. I'm wondering if it is the coral. That really sucks. The beads are lovely, especially the heart one.
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2013-11-04, 12:52pm
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Just suggesting it was a combination of the coral, size and soda. I've been making sodas for years and probably make more of them than anyone else. I know when I use corals I put them in the side of my kiln where the door stays shut (Glasshive). I've had plain coral beads crack just from a quick blast of cool air by opening the kiln.
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2013-11-04, 2:31pm
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Me either til now! So weird huh? That is the conclusion Hayley Tsang Sather and I have come up with. I am going to try a base of messy clear with an encasement of sunburst to see if that will work with no breakage. Thank so much. Ugh! I know, you know it HAD to be the heart one that broke too! Grr
I wondered about that too, Julie. I did put that bead through some hell making it. Although the one I made in bright lime green is the same style and just fine. I also made a n XL one in black with ivory sides and that one was fine too. You know when I make the XL's I put them on the far right side and then start loading from the left side for the others. So I will make maybe 2 xl ones and then focus on smaller sizes. So the kiln would only be open long enough to put a focal in, then one another 40 minutes later. Hmm... Weird. Do you think coral is more sensitive to heat change? All corals or just Sunburst?
Here is the thread in the ISBG facebook page where we discussed this issue as well if you want to take a peek. https://www.facebook.com/groups/2262...=group_comment
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Genea Crivello
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2013-11-04, 3:22pm
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Not all corals but the ones that tend to be more yellow like Apricot and Sunbust. Apricot is the worst for me. I love using the color but watch it like a hawk. I'll use it for discs but anything else worries me.
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2013-11-04, 7:10pm
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Hmmm very interesting. I just heard from Evelyn Duberry that yellows and oranges tend to cool more quickly. News to me! I have been lampworking for almost 11 years and that is the first time I have heard that! Lol always learning something new Hmm my guess is that yellow apricot and sunburst are of the same family. I make it a game to figure out what batches they used to get what new colors This would totally make sense. I have heard they have been having trouble getting yellow apricot to turn out lately. I have mostly used my yellow apricot for smaller beads so I never noticed any problems. Thanks so much for your info
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Genea Crivello
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2013-11-04, 7:40pm
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Gorgeous glass! I will be curious to see if you can resolve the issues. The beads are beautiful.
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2013-11-05, 6:09am
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weird
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Quote:
Originally Posted by mtnglass
Not all corals but the ones that tend to be more yellow like Apricot and Sunbust. Apricot is the worst for me. I love using the color but watch it like a hawk. I'll use it for discs but anything else worries me.
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Yep. The yellow'er the coral, the crackier. Though 419 isn't technically a coral, it might as well be with a number like 419 and that oddly stiff soupiness in the flame. If it quacks like a, I mean cracks...
Genea, remember that time I told you about how the cracked bead with a base of 419 (apricot) was sitting on a table and literally repelled each half of itself about 3 inches away from where it had been, and in opposite directions? I wasn't exaggerating.
Sarah
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2013-11-05, 6:15am
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I'm betting that the larger press is sucking out more heat than the smaller ones you use and you have to find your 'happy place' with it. This makes sense with the bead that is only cracked on the coral not the raku, because it appears that the raku was spot heated and twisted (correct?) that color is not only floating on the surface blocking the coral fromthe heat (much like a brimmed hat in the sun keeping you cool) but is always closer to the heat source. The coral below even partially exposed is taking in heat and being robbed of it by the cooler core. The cooler core of the bead becomes it's own heat sink. The simplest way to explain it is comparing it to making a too big bead on a hot head. Eventually you get so big it becomes hard to melt in surface applications and get a good smooth surface, even though it seems like you should always be able to melt the outside surface, at some point the heat is just being absorbed and not melting in. And by big on a HH I mean I tried to make a shifter knob one day just cuz... On the HH..... Ya. Anyways, you just have to find your happy place lol. This technique in steps is probably still possible if you keep the baking soda part to close to the very end if you don't want to heat the bead too much. You might have to rethink the raku application for some.
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2013-11-05, 8:59am
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Would a clear core help?
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2013-11-05, 9:38am
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Thanks, Caliente! Me too. I am way determined that way. As you can see a few cracked beads didn't stop me yet! Close though...
Sarah-Lol, Very interesting. I am so surprised I am just now finding out about this weird yellow/orange thing. Good to know though!
NO! Holy crap! WEIRD!! Glass is such a strange creature, isn't it?
What great insight Jaci! Yeah that totally make sense. Well putting all of the info together with heat/colors really sheds some light on these issues.
Wow, you must have wanted a challenge to make a shift knob! Lol. I worked on a HH for many years before upgrading Hmmm, yeah I will definitely keep these things in mind when choosing a base color.
This was suggested to me about a handful of times, Kristin so it sounds like this is a really good solution to the problem.
I once made this GORGEOUS clear cored red roof tile heart with a clear center. The bead broke and I was so devastated I never used clear for a core again! I will post my results after trying this! Thanks so much.
xo Genea
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Genea Crivello
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2013-11-05, 9:47am
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Try a clear core. Corals don't like thick
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2013-11-05, 9:59am
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Quote:
Originally Posted by Genea
I have heard they have been having trouble getting yellow apricot to turn out lately. I have mostly used my yellow apricot for smaller beads so I never noticed any problems. Thanks so much for your info
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The last batch of Apricot was very different in rod. Very close to Tequila Sunrise in appearance. Seems the same when melted.
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2013-11-06, 11:23am
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Since it is happening right by the hole/mandrel it may not have enough heat, and/or thickness there. I can't remember the exact rule, but I think it was needs to be thicker than the mandrel itself on each side around the mandrel itself. So particularly with a lentil where it narrows at the edges it would be more likely to develop a running crack. Just a thought.
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2013-11-09, 1:19pm
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Thanks Mr. Smeeth! This has been the most popular suggestion and IT WORKED!!
Yeah, I heard that Papaya was also made from Yellow Apricot. I agree with your thoughts on Tequila Sunrise Julie!
Yep, you are totally correct on those thoughts Echo! This was another comment on why I may have been having problems.
Here is the newest focal. IT WORKED!!! I used Messy clear as a core and encased it with the Sunburst coral. No cracks!! Yippie!!
Thanks so much for your suggestions everyone! xo Genea
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Genea Crivello
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2013-11-09, 2:23pm
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Lovely bead! I'm glad you got it sorted out.
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2013-11-13, 4:55pm
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Yay!
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2013-11-20, 6:58pm
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Quote:
Originally Posted by Genea
Hmmm very interesting. I just heard from Evelyn Duberry that yellows and oranges tend to cool more quickly. News to me! I have been lampworking for almost 11 years and that is the first time I have heard that! Lol always learning something new Hmm my guess is that yellow apricot and sunburst are of the same family. I make it a game to figure out what batches they used to get what new colors This would totally make sense. I have heard they have been having trouble getting yellow apricot to turn out lately. I have mostly used my yellow apricot for smaller beads so I never noticed any problems. Thanks so much for your info
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I definitely do not mean to disparage anyone, and hope everyone understands that. With that said, my suggestion would be to not believe everything you hear in the glass world. In this case, specifically the "news" you received regarding quicker cooling. There is a good reason you've never heard this before - it isn't true. Opaque cadmium-selenium colors (i.e., the range of yellow/orange/red) have some specific reasons they are more susceptible to cracking than other colors. Losing heat faster than other glasses is not one of them.
Without getting into a long explanation of glass chemistry, the short version is that the COE of Cd-Se glasses can change when they are worked for a long time. The more trips up and down in temperature, or the longer they are held at a high temperature, the more likely their compatibility will change. Generally speaking, they also tend to have a somewhat higher annealing temperature than most other colors. I doubt these are the only reasons you had cracking problems with your beads, but I certainly think it is/was part of the issue.
Also, regarding the use of sodium bicarbonate to change the texture on the surface of the bead. Sodium is a strong flux that increases the COE and lowers the viscosity of glass. So doing this changes the COE of the surface glass and introduces extra stress into your bead, making it more likely to crack. I'm not saying you should never use this technique, just be aware of the issues it can cause if you do. The flip side of this coin is that the bubbly surface created can help absorb the extra stress introduced into the glass by the change in COE. But you still need to be careful.
Brad
P.S. I tried very hard not to comment on this so as not to offend anyone, and I very much hope I didn't. But there is so much hearsay based misinformation floating around the studio glass world that I finally concluded that not commenting on this would have been more of a disservice than anything.
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2013-11-20, 8:45pm
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silver glass addict
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Awesome information, Brad! Thank you so much for taking the time to share with us your expertise in glass making!
Quote:
Originally Posted by glassmaker
Without getting into a long explanation of glass chemistry, the short version is that the COE of Cd-Se glasses can change when they are worked for a long time. The more trips up and down in temperature, or the longer they are held at a high temperature, the more likely their compatibility will change.
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Loren warned us about using Cd-Se glasses for our butterfly murrine but never gave this thorough an explanation. Two of the murrine made with Cd-Se glass cracked on the last, fifth, day … exactly what you described regarding multiple trips up and down in temperature! Thank you again!
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2013-11-21, 5:44am
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That's great info, Brad. I love to learn all I can about glass chemistry and there is not a ton of info out there that I have found. I'll take the tidbits where I can get them. Thanks!
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2013-11-21, 7:24am
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That is really interesting, Brad! Thank you for sharing this information with us.
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2013-11-21, 8:24am
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The yellow orange thing and COE shift is also true for fusing - BE warns against taking oranges and yellows through too many heat cycles as it will cause compatibility issues.
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2013-11-22, 3:04pm
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burnin' glass just becuz
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Quote:
Originally Posted by glassmaker
I definitely do not mean to disparage anyone, and hope everyone understands that. With that said, my suggestion would be to not believe everything you hear in the glass world. In this case, specifically the "news" you received regarding quicker cooling. There is a good reason you've never heard this before - it isn't true. Opaque cadmium-selenium colors (i.e., the range of yellow/orange/red) have some specific reasons they are more susceptible to cracking than other colors. Losing heat faster than other glasses is not one of them.
Without getting into a long explanation of glass chemistry, the short version is that the COE of Cd-Se glasses can change when they are worked for a long time. The more trips up and down in temperature, or the longer they are held at a high temperature, the more likely their compatibility will change. Generally speaking, they also tend to have a somewhat higher annealing temperature than most other colors. I doubt these are the only reasons you had cracking problems with your beads, but I certainly think it is/was part of the issue.
Also, regarding the use of sodium bicarbonate to change the texture on the surface of the bead. Sodium is a strong flux that increases the COE and lowers the viscosity of glass. So doing this changes the COE of the surface glass and introduces extra stress into your bead, making it more likely to crack. I'm not saying you should never use this technique, just be aware of the issues it can cause if you do. The flip side of this coin is that the bubbly surface created can help absorb the extra stress introduced into the glass by the change in COE. But you still need to be careful.
Brad
P.S. I tried very hard not to comment on this so as not to offend anyone, and I very much hope I didn't. But there is so much hearsay based misinformation floating around the studio glass world that I finally concluded that not commenting on this would have been more of a disservice than anything.
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Hey Brad,
Thanks for the fact-based analysis! I was guessing about the cooling based on my experiences - as it seemed to tbe the only thing that made any sense just from watching the glass while i worked (compared to other glasses) plus where it would crack once cooled (usually ends 1st, then anywhere thinner than the rest). i work pretty large and sculpted and for the most part the only beads that break for me (regardless of how careful I am) are opaque yellows & oranges and they don't just crack, they desintegrate - unless i use a clear core.
I anneal at 980F and have a very conservative cycle - any tips for working with opaque yellows and oranges? I'd really like to make a big (5"+) soft glass sculpted piece in oranges/yelows but have always been concerned about the long term stability. The way I work any bead will be constantly being cooled and reheated as i sculpt and decorate each area and regularly flash to refheat the whole piece over a period of an hour or more...
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2013-11-22, 3:05pm
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burnin' glass just becuz
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Quote:
Originally Posted by Genea
Thanks Mr. Smeeth! This has been the most popular suggestion and IT WORKED!!
Yeah, I heard that Papaya was also made from Yellow Apricot. I agree with your thoughts on Tequila Sunrise Julie!
Yep, you are totally correct on those thoughts Echo! This was another comment on why I may have been having problems.
Here is the newest focal. IT WORKED!!! I used Messy clear as a core and encased it with the Sunburst coral. No cracks!! Yippie!!
Thanks so much for your suggestions everyone! xo Genea
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YAYY i'm glad that worked for you!
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2013-11-25, 10:04pm
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I wish I could offer you something useful Evelyn, but I really can't. The physical characteristics of cadmium-selenium glasses make them a problem when doing the type of work that you want to. It sounds somewhat ridiculous, but when worked long enough this type of glass can actually become incompatible with itself.
One thing that can help is to keep it thin in order to help minimize the overall stress level. That's a large part of the reason that using a clear core helps reduce cracking. Keeping the layer of yellow thin enough can help keep the overall stress below the breaking point.
Another thing is to work as quickly as possible to minimize expansion changes. Unfortunately, that sounds pretty difficult with the work you want to do.
The last and most reliable potential solution - as completely unhelpful as it is - would be to use a different color.
Brad
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2013-12-05, 3:43pm
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Thanks for that information Brad. Sometime I think I for get that having the glass in a near molten state is actually "cooking" the recipe of chemicals that make up the glass and this "cooking" changes the contents. The soda flare that we don't see because we are wearing our glasses is not just a pretty yellow light but actually soda burning into a gas and going up the ventilation fan.
This makes me wonder if getting to the finished bead as quickly as you can will reduce the likelihood of cracking.
( Chemistry is fun! Phillip likes to play with fire!!!!!!!)
__________________
The Zombie Apocalypse is Upon Us.
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2015-08-20, 6:15am
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Member
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Join Date: Apr 03, 2010
Location: Mauritius
Posts: 58
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Thanks for the info Brad. I have learnt a lot.
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