Author Topic: Identifying type of crack in class  (Read 2035 times)

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Offline Missc

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Identifying type of crack in class
« on: October 24, 2008, 02:17:05 PM »
Hi, I am brand new to the board. I have been buying what I think is murano glass and will try to get photos later to ask you about my pieces. Some I have found on other murano sites where they sell it so that may be a good thing.

I just got a piece from E-bay. It's a very heavy bowl in an unusual deep orange/cantaloupe color on the outside with some pretty nice large bubbles in it, with a dark green glass and light gold dust swirls inside. On the outside it is cased in clear glass. I'll post pictures of it later. Anyway, it arrived well packed but it has what looks like a 3" crack UNDER the clear glass casing on the outside. It is far from the top, inside the polish so you cannot feel or see anything at the top of the glass (like a crack line). I was really, really bummed out when I saw this. It wasn't in the description so I thought maybe it happened en route. I let the seller know and I am waiting to hear from him but even with the flaw, I don't want to send it back. It's such a pretty color. It's ugly and pretty at the same time. I doubt this is vintage though. While it is very heavy, I feel it is probably modern. At any rate, I would like to know WHAT you call that kind of crack. I called it a stress crack...It certainly stressed me out.


Offline soledivo

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Re: Identifying type of crack in class
« Reply #1 on: October 24, 2008, 05:40:54 PM »
hi there,

i think the type of crack you mention can be done at the time of manufacture,

or like me its been put under a hot tap, realizing the mistake I then put it under the cold tap.

After ruining the piece, I just stood there in disbelief that I had dome such a stupid thing.

I have a lovely dancer figurine that has this crack under the glass, luckily at the back, I assumed its a fault at time of making.

 
martin


Offline Frank

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Re: Identifying type of crack in class
« Reply #2 on: October 24, 2008, 10:07:04 PM »
Such a large crack is unlikely to have been there when it left the factory. These cracks are stresses in the glass that have not been removed by healing, in cased pieces these are often seen in only one layer of the glass.
Frank A.
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Offline TxSilver

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Re: Identifying type of crack in class
« Reply #3 on: October 25, 2008, 06:21:22 PM »
Glass sometimes cracks itself. I've read that sometimes it occurs during annealing or sometimes later due to a flaw in the glass or incompatibility of abutting glass types. I am not a glassmaker, so I don't know first hand what causes the cracks. If the crack was not described, I would return the bowl to the seller. If you are like me, the crack will be the only thing you will ever see in the bowl. It was unfair to pass a problem piece to you without your knowledge. A crack is a crack, no matter when it occurs.
Anita
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Offline Frank

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Re: Identifying type of crack in class
« Reply #4 on: October 25, 2008, 07:53:49 PM »
... have not been removed by healing....

Of course I meant annealing  ;D
Frank A.
Please help preserve glass web-sites for posterity by donating to The Glass Study Association a non-profit organisation.
Scotland's Glass - Ysart Glass
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Offline Martyn K

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Re: Identifying type of crack in class
« Reply #5 on: October 26, 2008, 10:05:38 AM »
I thought this was going to be a post about drugs education from the title....

Offline TxSilver

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Re: Identifying type of crack in class
« Reply #6 on: October 26, 2008, 07:10:27 PM »
I'm afraid this time it is another vice -- undisclosed damage.  :o I know how Missc feels. I bought 4 things off eBay in the last 2-3 weeks. Three of them had undisclosed damage. It is so disappointing to look forward to something, only to feel those sharp points or see the breaks. Sellers like these, whether missing the damage was accidental or intentional, certainly do a lot of damage to eBay.
Anita
San Marcos Art Glass
Visit the Murano Zoo
http://sites.google.com/site/muranozoo/

Offline bicard

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Re: Identifying type of crack in class
« Reply #7 on: October 27, 2008, 01:13:30 AM »
quoted from Conservation of Stained Glass in America "  ITERNAL STRESSES IN GLASS ARE BY AND LARGE INVISIBLE AND UNPREDICTABLE. ANNEALING CRACKS, THOSE CAUSED BY HEATING OR COOLING, CAN APPEAR AT ANY TIME THE GLASS IS PUT UNDER STRESS. SOMETIME THEY CAN BE CAUSED BY CHEMICAL IMBALANCES IN THE MELT."

"GLASS THAT HAS BEEN EXPOSED TO A FIRE WILL ALSO DEVELOP ANNEALING CRACKS. WHILE MANY WILL DEVELOPE THE CRACKS WITHIN DAYS IT MAY CONTINUE FOR YEARS AFTER THE FIRE"

That being said the cracks under the surface of your glass could have come from the stresses of traveling to you.  The shipper may never have known they were there when listing.

Just as the member who exposed hers to hot water.  For differing mixes of glass needed different annealing (read heating and cooling)times. when re-heated your glass you inadvertantly cause change that timing, hence new cracks. Your very lucky it didn't explode like some kitchen ware does at times.

my two cents as a stained glass artist.
GLASSDREAMS STUDIO
STAINED GLASS
CRACKS ME UP

Offline Artofvenice

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Re: Identifying type of crack in class
« Reply #8 on: October 30, 2008, 04:17:04 PM »
I agree at 100%. The crack can run inside the glass, often very slowly, sometime faster or it may collapse.
May be the seller didn't see any damange before packing.
It is so sad when a nice piece cames out from the annealing oven with a crack inside... but more sad when the piece looks perfect  :), you put on the table and you can hear a wrong sound...  :spls: and the crack is hidden somewhere   :'(

Ciao

Alex

www.artofvenice.com

Offline Missc

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Re: Identifying type of crack in class
« Reply #9 on: December 20, 2008, 11:05:49 PM »
 :fwr: I want to really thank all of you for your help. I contacted the seller and she refunded me more than half of the price. It is indeed a large crack that may have happened during shipping or in a weakness in the glass. I don't know if anyone will ever read this but I really appreciate the time that everyone took to answer me.

I'm a teacher and at that point, I was getting really swamped at work and never got back to the board until now (12/20). I didn't think anyone would answer. I was so wrong.

In the past month or so, I've bought some glass that I will need help identifying. I hope you can all help me. I'm totally out of money and cannot afford the gorgeous books that are out there until maybe a year or so down the line.

Again, thank you so much for your help.

 

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