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richsantaclaus

Incompatible Coe In The Glass

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Hi everyone. I was torching and thought I'd make a marble that contained too different COE's (coefficient of expansion).

When a marble is made, if there is too much of a difference of COE in the glass, incompatibility issues will surely arise and cause chips, cracks and breaks in the marble. The trouble is, one can't know when this exact event will happen. Even though I gave this marble the correct kiln time, it still had problems.

I made the spread of the COE numbers way apart to insure a good example of what happens. I chose borosilicate glass (COE 33), the kind of glass you use in cooking called "hard" glass and included Moretti soft glass (COE 104). These COE numbers are too apart to ever make a marble that won't have problems as my example for you to see visually.

Not to get too scientific here, COE refers to the vibrating molecules in the glass itself. The "shaking" back and forth at the atomic level. Different types of glass and different colors of the same glass have different COE's. This fact presents a MAJOR problem when old vintage marbles are repaired using my torch as I don't know the original values of the COE of the old glass. To overcome this problem, I don't repair all marbles that people give me to repair.

Anyway, here are 2 pictures of the same marble. I hope I have helped in a small way to show you guys incompatibility issues and COE's.

post-2583-127316660166_thumb.jpg

post-2583-127316660917_thumb.jpg

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I am keeping it in a padded cigar box just in case it exploded. I had a hollow bead I made (1 1/4") shatter into thousands of little shards on my workbench over night - what a mess!

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What difference in COE's would still be considered okay in general?

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So far with the great number and variety of Jabo marbles that I have or have had I have only twice experienced two completely coming apart after being with me for a while. Like crumbling into dozens and dozens of pieces not just cleaved in half or thirds. Total disintegration. Sorta Cool actually. David

P.S. I'VE SAVED BOTH OF THEM TOO!

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In Fenton Glass - they range from COE 88 to 97 and the extremes are not compatible at all. 3 marbles cracked on me!

In Moretti soft glass, the COE ranges from 102 to 106 and usually has no problems. Sometimes, the transparents buried deeply in encased glass cause problems.

In hard glass (Boro) green glass hates to be encased and usually always causes problems.

I invite anyone to come over and torch with me so i cna share the craft!

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So far with the great number and variety of Jabo marbles that I have or have had I have only twice experienced two completely coming apart after being with me for a while. Like crumbling into dozens and dozens of pieces not just cleaved in half or thirds. Total disintegration. Sorta Cool actually. David

P.S. I'VE SAVED BOTH OF THEM TOO!

I have had a few issues with Jabo glass not cooperating with me too. I had them cut in half, separating the "bad" parts from the "good" parts and melted the good parts together to make an entirely new marble! I took the "bad" halves and hand-pulled the problem part (where it cracked) and tossed it away and used the remaining glass to make new combined marbles - so far, no troubles! I have melted together different Jabo marbles to make bigger ones - it's kinda fun!

Anyone interested in seeing them?

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Yes please.

Wish I didn't live on the opposite coast, I would take you up on your marble making offer. I so want to learn how to make them.

Pen

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Very cool stuff! I do have a question: does the shattering happen under the torch or in the annealing oven? Or both?

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Under the torch, it never shatters since it is molten and in liquid form state of matter. It cracks after cooling (I have my kiln set at a very slow cooling rate (it takes 10 1/2 hours to get from 970 degrees F to 400 degrees F). The thing is, sometimes it shows cracks immediately and sometimes it takes a few weeks!

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