Oh cracks! How much heat does it wasn't?
 

Okay, I know I am just starting...

BACKGROUND
Less than 20 hours torching
2 marble classes (8 hours)
Alpha on propane + oxygen concentrator 10psi 20 lpm
Effetre glass
Done few marbles (not pretty), melted and worked on gathers, worked on puntys (remove cold weld), thin and thick stringers, mushroom pendant
Glass Hive kiln

ISSUE
Trying to make an off mandrel fish and it always cracks at some point.


I have watched many many videos, I have a lot of the must-have books, and have purchased and collected a "few" tutorials. I know the piece have to be constantly hot and reheated...

The last (4 in a row) one, I kept reheating so much that it kept melting and i could never get a shape to stay, of course. So I backed off and... Crack it goes. The kiln right now is working on a school of dead fish.

I tried not to make the fins not so thin, tried leaving them for last, tried not heating at all the parts that were done (like the Italians do - someone recommended the dvd by Vittorio and that is in the mail right now)...

I watched Mr. HyperT's video on a chevron fish and I felt I was going through the same motions (certainly not as neatly)...

Should I just keep going and eventually it will click how I am supposed to do?

](*,)

Thanks a lot if you read this far!

Time to sleep and try again tomorrow more rested...

yes, or try doing smaller pieces first. You'll get an eye for how the glass looks at different heat levels and different flames. Perhaps some pics of where you are experiencing the cracking on the piece? Admiring your dedication, you are clearly hooked :)

Im new to the torch as far as glass too. I made some big marbles and pendants that just break. I have no kiln till next month.

Im thinking a 2 stage torch with a foot peddle to heat everything up all at once is in my future. Iv been turning my torch up and down to heat the whole work then down to do a detail then back up again.,,,,

Try using a bushier flame if you can. You don't need to blast it to keep it warm, just bathe it in a gentler flame further out. Try making something smallish on your rod and see how long you can hold it outside the flame before it cracks, and find the areas next to the flame where you can park it and it'll still keep warm but not be directly in the flame.

If you brush a cooler area of glass with the flame it'll crack, whereas if you brought it in more gradually it wouldn't.

I find scuptures to be much more challenging than marbles. Go back and work on your marbles until you can get a consistantly round wrinkle free marble. There is more to learn making marbles than meets the eye. First of all they are quite forgiving when it comes to heat and temperature. Secondly learning to read the heat in a marble is a subtle thing, too hot and the punty welds to the marble, too cool and it pops off. Secondly, when is your fish cracking? When you place it in the kiln or when you are reheating it? Where is it cracking? Does it crack between two colors? Does it crack at where two different thicknesses come together? There are lots of reasons for cracking.

Thanks sooo much for all the help!

I have been working on small things, and I will post some pictures.

They crack right as I am working on it. Not even between two colors. And not necessarily on the thinnest part either. You can see on the pictures...

It makes perfect sense to reintroduce it slowly, outside of the flame. I still have to practice on the bathing thing. I was with the impression that it needed a lot more heat, which would just melt everything (well, the way I was thinking). I will work on less.

I really like the exercise of finding out what cracks and where! That will for sure be my next action.Thanks

Great point on the bushier flame. I did not try that. And by bushier, you mean more gas only or gas and oxy?

I like making marbles. I did play with puntys and could not get a consistent off. All along thinking the punty was too hot but must have been the marble. I get it. Back to the bench!!

Let me do some more work and I will report back.

Meanwhile, here are the pictures to follow...

From fish to blob
 

This cracked and then I just played with it..

Almost!
 

I figured would use one color and avoid color cracks... Missed the tip fin and flipper on other side..

Being brave with more colors
 

I thought I was home free when I heard that familiar noise but it was holding together. Loaded in the kiln and it survived together for a minute...

Argh! Lost the mouth
 

So, i am not a good plastic surgeon... The mouth cracked right off but I decided to remelt it in, no matter what!

I was paying good attention on keeping it hot, but maybe too hot and most likely let it cool down at some point and back into the flame too quick...

That's it for now.

A bushier flame is obtained by lowering your pressure at the regulators, you will need to open the torch vales a bit more but the result will be a lower velocity flame. Yes, if your punties are welding to the marble the marble is too hot. Also it it "catches" on the edges of your mold it is too hot. Your fish look very nice.

Bushier flame worked much better! I turned down the regulators and off I went.

I need to experiment some more but I can see there are trees in this forest!

I worked on a nice big marble for a long time...pundits coming off nicely... Until I put it in the kiln and went to show my daughter later...crack!

I worked on eliminating the last punty by dropping the marble in the mold and cleaning it in there...I think that was the culprit.

On to get some proper grabbers.

So much to learn, so little time!

Argh!

On a good note, i got some beads that survived...

The marble was toasted and the spinning top too?!

What a pain. I guess i have to work on keeping these big pieces hotter!?

Spinning top

And marble

Just wondering since you are in Michigan - where are you torching and what is the temperature around you and the glass? I used to live in Chicagoland and torched in the garage and found out that the glass would break because of the cold surrounding air.

Just a thought.

Katherine,

I torch in my basement, so it is nice and warm...

Well, I here, at least!!

Hey I'm in AZ and I get more cracking during the winter due to the colder air (I work outside too) so that is definitely a factor. IMO that cracking looks a little strange to me but I don't work off mandrel. It looks like some incompatibility cracking going on.

Kat that was one ? I was wondering about HOW warm does you're working
area need to be to help with cracking problems ?
my welding shop has 16' walls & 2000 sq' inside & about 45 two 50 Degs in the winter
100% humidly I live in northern ca in the rain LOL

down the road I will build a inclose studio on the upper deck once I clean it out LOL
Steve -- just getting started in glass I am a metal smith & welder

You know, I noticed it is a bit cold, since the windows are opened. When I wrote first, the windows were closed and it was nice and toasty!!

With that in mind, I moved quickly into the kiln this time. And yes, success!

I kept the marble much warmer and paid extra attention not to let it cool down during the process. I made one very similar to the one that cracked yesterday. Let's see later on, but it has survived the transition torch-to-kiln.

I also played around with a piece as if I was sculpting something, different colors and different thicknesses... Found the "hotspot" to park and still be warm. Also found how long did it take without soaking for it to crack! Worked on it some more and quick into the kiln it went.

Work in progress for sure.

I got that Corning video of Vittorio Constantini... Holy cow!

But I have a question on his work: I see him sometimes holding his work with hands, which tells me it is cool enough. Does that mean he would have to put it in a cold kiln and then have a ramp up program? If it is cold to the touch, and it went directly to a kiln at 900+ it would crack, no?

Can't thank all of you enough for the help!!

To my question above, how come this doesn't crack? Is it thrown in a cold kiln that ramps up slowly?

http://youtu.be/WFwtVo6NrEY

It's thin enough that the temperature does not cause serious stress.

Aha! I will bench test it next. Thanks Roy.

You still need to be mindfull of the heat. This is one reason I went to the darkside, the other, as a marble maker, was for the clear.

Roy, the marble worked! I didn't spend time on cleaning the last punty remaining in fear of cracks but to me it looks great! I will take the chance next time. I need some sort of grabber...

I can see lots of marbles in my path!

that looks great!

At least you have a kiln, I am using a bucket of perlite.

Now that I have an oxygen concentrator and natural gas for my torch I can run till my arms give up and do larger work without having to conserve on gasses.

Larger solid works need a kiln bad.

I am getting a kiln next month no matter what.

Nice looking marble, I still can't do implosions! :) I polish the punty scar off while the marble sits in my marble mold. As long as the mold is hot from making the marble it should not be a problem. Us use marble tongs to move it from the mold to the kiln, the tongs must also be hot.

Thanks everyone! Yesterday I got two more in...

Roy, i did like you said, with the marble in the mold. Rushing like crazy!

Snoopdog, I almost got a kiln without electronic control! I am glad I got this cool glass hive one!!

I ordered that hemostat with loops, let's see how it works...

This looks better in person..