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Tips, Techniques, and Questions -- Technical questions or tips

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  #1  
Old 2019-06-09, 6:36am
Baelz Baelz is offline
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Default Soft Glass Breaking

Hi all. I had posted this on another forums and was told the community here may be more helpful. Thanks in advance for any advice.

I am melting soft COE 104 glass with a hot head. I used to use a fiber blanket to cool them, but mine has gotten a little beat up. Now I am using a crock pot and vermiculite(spelling?). I have noticed that in the last few days all of my small marbles I am messing around with are cracking into many pieces when I pull them out.

My process:
Turn the crock pot on while I am playing and making my marbles. Usually about an hour. I let the glass cool to not hot red and then I place it into the crock pot about 2 inches deep. I keep the crock pot on high for 1 hour then turn it off. I then wait 2-3 hours before taking them out. It worked for about 1-2 days, but the last 2 days everything has been cracked into pieces.

The marbles I make are like 0.5 inches thick. Clear or colored.

Why are they cracking? I know I should get a kiln, but I haven't saved up for that yet and I still want to play and learn different techniques. What can I do to prevent them from breaking?

Thanks!!
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  #2  
Old 2019-06-09, 8:50am
Floorkasp Floorkasp is offline
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That must be so annoying!
Keeping soft glass marbles in one piece without them going straight into a kiln is tricky. But you'd think that if you could make it work with a fiber blanket, you should be able to make it work with vermiculite.
One thing I can think of is that maybe the marbles touch each other in the crockpot? So one will have cooled down quite a bit, and then gets 'hit' by a really hot marble coming in.
Another thing I can think of is the tool you use to put the marble in the vermiculite. That is a step that you have probably changed from how you would put them into the blanket. Maybe your tool is too cold?
For my pieces that do not need to go straight in the kiln, I use Japanese annealing bubbles. They are not an actual alternative to annealing, but they are much nicer to work with than vermiculite in my opinion.
Good luck!
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  #3  
Old 2019-06-09, 9:01am
Baelz Baelz is offline
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Thanks. This last time I did have 2 in there at the same time. I did try and keep them separate. Perhaps they were too close and that is what caused those to crack; however, I usually do one at a time. I can try to heat up my tool some prior to placing the marble, though. Thanks.

With the Japanese annealing beads is the process similar to what I am currently doing with the crock pot and vermiculite?

My goal isn't proper annealing. I just want them to cool without breaking so I can see what they look like cold and find imperfections in them that I can learn from. I am not selling any of the things I make. I am just trying to learn and have fun. It's just discouraging/sad when they break.
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  #4  
Old 2019-06-09, 9:40am
LarryC LarryC is offline
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The myth of using vermiculite and crockpot or fiber blanket is fairly prevalent here. It is not something that is widely done in ANY other glass community though. You cant rely on it as a method. You may get away with it at times and then at others you will get bitten by it. Full annealing in a kiln is a necessity. Do whatever you have to do to get a kiln up and running. What background do I have to allow me to say this? I have 13+ years of soft glass hot shop experience and 8 years torchworking boro.
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  #5  
Old 2019-06-09, 10:10am
Robin Passovoy Robin Passovoy is offline
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You can't do soft glass marbles without annealing them properly, trust me, but I have had some luck with small marbles made from strips cut from Spectrum stained glass, which is roughly 96 CoE and a bit more forgiving of fast cooling in vermiculite.
You might want to invest in an actual annealing kiln, such as a Jen-Ken Chili Pepper. I've got one and I love it--they're durable, dependable, programmable, and it can handle my biggest marbles (~2") without them coming out in pieces. Chili Peppers aren't the cheapest out there, but they're worth every penny.
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  #6  
Old 2019-06-09, 11:05am
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All good information above.

And yes, I just came from a class and it was repeated many times "never touch hot glass with a cold tool"
You can just waft it in the flame a couple of times before touching the hot glass, you don't want it red hot or anything.

Also, what color were you putting in the marbles? The hot colors (reds, oranges, yellows) do not like being encased for example.
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  #7  
Old 2019-06-09, 12:11pm
Baelz Baelz is offline
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I used clear with dichoric green and a lilac color with yellow, green, and pink dots. I am not super surprised the 1st broke, but I was about the 2nd one. I just wish there was something I could do in the mean time that would prevent my glass from cracking while I save up for a kiln. I will try heating the tool up some first.

Ty all for the help thus far.
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  #8  
Old 2019-06-09, 2:07pm
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And are you absolutely positive the glass was all the same COE, that is the only other thing that comes to mind.

Also the fiber blanket can still work if it looks a little ratty, so maybe try that again.
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  #9  
Old 2019-06-09, 4:24pm
Baelz Baelz is offline
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Yup, I am sure. It's the only glass I have purchased thus far.
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  #10  
Old 2019-06-09, 11:19pm
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Locococo Locococo is offline
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There' re some clear glasses and dichro that doesn't match. My experience is that round beads are the most forgiving when it comes to cooling. Every other shape is far more susceptible. You said they crack in many pieces. Maybe you can be some more specific.

What glass exactly, what dichro?
How big are the marbles?
How do you put them in the pot?
How do you melt off the last punty?

Sometimes it' s just one little thing and that must not be the kiln.
If the marbles are not that big, let' s say about 10 to 15 mm it' s doable without kiln.
Of course a kiln is required.
But cracking in many pieces makes me suspicious that it might be something else.

Elke
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  #11  
Old 2019-06-10, 9:48am
Happy Glass Studio Happy Glass Studio is offline
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I have a feeling it's one of two things. either cold tools or inconsistent heat. Cold tools on warm glass pull the heat from the places they touch and create stress. Another thing that might be happening is that you are rushing the process of getting it into the crock pot. I had this problem from time to time too. Because you aren't putting it into a 900 degree kiln, you need to make sure you bring the entire temp of the marble down by flame annealing. You may be waiting for the glow to disappear, but this can mean that the outside layer is much colder than the inside core. So after the "entire" glow of the bead has gone, make sure to wave it through the flame a few more times - not to get it molten or even red hot, but enough to bring the surface temp back up to something similar to the core temperature. I can't promise perfect results every time - as others have said, glass compatibility may be an issue too - but this should definitely help.
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  #12  
Old 2019-06-10, 7:31pm
Baelz Baelz is offline
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The marbles are about an half an inch. I put them in with a metal forcep that, on the end, is curved on either end so you can completely wrap it around a circular object. The metal is almost always room temperature. I melt the little bit from the punty off by holding the marble with this forcep trying to only keep the glass in the fire and not the forcep. After I do that I let it cool for a few seconds and then put it into the pot.

After reading everything I will try and heat the forcep up some prior to picking up the marble. Maybe that will help.

I only know it is COE 104. I can't remember exactly where I got them as I bought a bunch awhile ago from a couple different companies.
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  #13  
Old 2019-06-11, 3:57am
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I make a lot of soft glass marbles in the 30 to 40 mm range. They never get in touch with any metal tools just graphite. I shape the marble in a preheated mold and also melt off the punty this way. And the marble is still in the mold when I put it into the kiln.
And for me it's really important to know the brand of my clear glass and dichro.
As I said before there' re clear glasses that doesn' t match with some dichro.
To rule out certain mishaps you can start series of tests.
I would begin with a solely clear marble then clear and dichro, then clear and different colour glasses and so on.
I'm curious what will be the results.

Good luck!

Elke
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Last edited by Locococo; 2019-06-11 at 10:31pm.
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  #14  
Old 2019-06-11, 6:26pm
Baelz Baelz is offline
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Even one of my marbles that was just a solid color with some dots broke. No clear and no dichoric.
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  #15  
Old 2019-06-12, 3:47am
Floorkasp Floorkasp is offline
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Larry wrote this: 'The myth of using vermiculite and crockpot or fiber blanket is fairly prevalent here. It is not something that is widely done in ANY other glass community though.'

This is the opposite of what I have found, having spoken to beadmakers in many countries with a history of lampworking. The focus on annealing in the US is unlike any other place I have visited. In most countries around the world, kiln annealing small glass objects is simply not done. This includes places where kilns are simply not available and places where the skilled glass workers manage to make the pieces in such a way that stress in the glass is reduced while making it. For bead (and marble) makers who are still fairly new, or working experimental, or for specific shapes, larger shapes, etc, I will always recommend the use of a kiln. However, it is not so black and white as we sometimes think it is.
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  #16  
Old 2019-06-16, 8:19pm
Baelz Baelz is offline
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I adjusted my technique a little. Now I keep the marbles in the crockpot with vermiculite for 2 hours and let it cool for 1.5 hours. Additionally Input my abused fiber blanket on top of the vermiculite and then the lid. That has been working well for me.

Now my problem is my hot head torch works amazing for like the 1st 15 minutes and then the flame starts to get smaller and die down. It doesn't heat as well as it did when I first turned it on. Why? It is a brand new bottle of MAPP//PRO too. This has occured on every bottle thus far (3)

Last edited by Baelz; 2019-06-16 at 8:22pm.
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  #17  
Old 2019-06-17, 4:27am
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The gas gets cold with use, and doesn't flow as easily. Some people keep it in a bucket of warm water I have heard. Some use a larger tank and a hose instead of the small canisters.
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  #18  
Old 2019-06-17, 6:26am
Baelz Baelz is offline
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Ooh, that makes sense. Thannks
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  #19  
Old 2019-06-17, 9:11am
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echeveria echeveria is offline
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I used a heating pad wrapped around my canister when I used a hothead. Just remember to turn it off when you quit working! It did not totally resolve my issue, but it extended working time for quite a while. I think mine was designed to cut off after a while so that the user did not burn themselves. There may be some out there that don't do that.
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  #20  
Old 2019-06-17, 11:24am
Robin Passovoy Robin Passovoy is offline
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Gas under pressure liquefies, which is what is actually in those canisters and tanks. As you work on the torch, you're taking some of that pressure off, which chills down the liquefied gas and slows the flow. Couldn't tell you the physics behind it, but I've had frost forming on those little compressed-air spray cans that are used to clean out keyboards, and I once saw a propane tank that had been used in an outdoor ironworking demo during a rainstorm. That thing had sealed itself to the pavement in an inch-thick shell of ice!
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  #21  
Old 2019-06-18, 5:06pm
Baelz Baelz is offline
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Thanks everyone
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