Temperature or incompatibility? The wisdom of LE I need you!
 

Making a fan pull as a housewarming gift for a friend. Made and annealed the focal piece last week and it was fine; picked it up last night and noticed...cracks. Auuggghh!

Attachment 156851
Attachment 156852
Attachment 156853
(sorry bout the horrible pics; forgot the camera was still set for the eclipse photos)

I'm unsure if the cracks are due to temp issues (it's a big heart; 2 full rods just for the base, so maybe it got a little cool when I was adding the decor?), or incompatibility (which would be weird; the base is just CIM Mojito over Effetre Clear and all decor is 104 and used in other beads without issue, but the cracks look to me like incompatibility). Thing is, the colors are pretty close to her wall/furniture colors in the room the fan pull would be in. If it's a temp issue, well, friggin hell, but I can redo. If it's compatibility, I'll have to rethink all my colors ($^&@#*%!).

Opinions please!!

Alli

I don't know on the reason, but can you put it back on a coated mandrel, heat it in the kiln, and try to heal the cracks & see what happens? ( slowly slowly since it is so big)

LOL It's such a damn big bead I'd be afraid to Eileen; I'd probably have a heart attack if it decided to blow apart when reintroduced to the flame.

That would smart if any pieces landed on you for sure!

With them wandering around not in a straight line, it looks more like incompatibility than thermal cracks. That's too bad.

Sorry to say it looks like incompatibility, Alli! CiM may be the culprit. Sometimes glass combination may work in smaller beads when they are slightly incompatible but cracks on larger beads... Ask me how I know! Lol!

Maybe Effetre olive green instead?

Could you skip the clear and use solid mojito? I know it would be cost more, but you don't have a huge amount of decoration and the cracks don't seem to follow the decoration, so the problem may be the mojito over clear.

I find more cracking problems in really big hearts with vertical holes. The mandrel is a heat sink, then it looses more heat because of the crease. Each lobe of he heart is still large, so they retain more heat. Before putting in the kiln, I try to equalize the heat in the piece. The larger they are, the harder it is, IMO.

We often think of cracks as either incompatibility or thermal, but I often wonder if inconsistent heat doesn't aggregate incompatibility. Just my opinion though.

10 minutes held at the annealing point per millimeter thickness. Mt. Palomar telescope lens took 10 months to bring down to room temperature. They blew the first lens by cooling to fast.
This is especially important in thicker pieces. 25.4 mm = 1 inch x 10 = 254 minutes held at the annealing point. When the temperature reaches down to 500 degrees F you can vent the oven a bit
and cool faster.

I can see how the size would mean a slower ramp down time, that sounds like a big bead. Isn't a clear core the usual advice for glass that doesn't like to be encased? If it was a core of Mojito, I can see that being a problem. Those do look like incompatibility cracks to me too, that would definitely be my first thought. Sorry for all that work, it is a lovely piece!!

Poop poop poop. Yeah, I can try to remake with just a Mojito core, assuming my last 2 rods of it are enough. I initially cored it with clear so I would have some Mojito for the smaller beads; there goes that plan LOL. And I can easily up the annealing time. While I've made others this big and they've been fine, I do NOT want to do the same-ish bead for a 3rd time (I get bored easy and have such a short attention span...oh look! A light!).

Putting a coin in front of the wood base would give us a reference to the size of the bead.

Oh look, a squirrel!

You know, come to think of it, way back when I had a hothead and was cooling in a fiber blanket to batch anneal......I did some larger beads that had cracks like that along the side. It turns out they were hitting each other in the blanket, or too close and the hotter one would crack the cooler one, or vice versa. Also I might not have been heating evenly before I put them in.

So it may indeed be temperature related, as Kathy said it needs to be heated evenly. Was anything else in the kiln?

Hrmm. I am using a HH, but everything goes directly into the kiln and this puppy was in there all by its lonesome, so not affected by other bead temps.

And this is another bead made with the same press for size reference:

Attachment 156872

Squirrel? Squirrel?! SQUIRREL!

Oh wow, that is much bigger than I thought. How long did you anneal it for before beginning the temp drop, and how fast did you drop it?

I am going to guess thermal cracking now that you have mentioned the press.

Presses suck the heat of the glass fast than a Jedi Knight reacts to a light saber and getting the heat back into it with a hot head torch is going to take the patience of a Saint and the heat control of Oby Won himself as well as triple or quadruple the kiln soak and ramp down time of anything I have ever worked with or imagined.

See now, that is the fun of lampworking, you get to be all sorts of cool people!

Id try it in boro. Its not near as fussy.

LOL Ever try to melt boro with a HotHead? I'd be still trying to melt the same rod from the nursing home.

Gonna give it another go tonight. Got the kiln annealing time changed and will try a diff combo *fingers crossed*

Make it hollow! Way less glass and sturdier.

How DAFUQ do you make a hollow heart!?!!!!

By the way! Hi Alli! Miss you...

I'm so glad to s
Squirrel!

You melt the end of a tube into a gather and blow it into a two part mold.
Then cut it off the end like a Christmas bulb.

Good luck with that.

Oh of course. On a HH.

Lol.

Squirrel? Squirrell?! *grin* Good to see you girl (love the new avatar pic...ooooo, a light!).

And yeah, trying to make it hollow requires more coordination and dexterity than I'm able to muster LOL I'm going to to the stringer test to check compatibility (why this never occurred to me before, I haven't the vaguest idea). Then I'll have a better idea if it's compatibility or temp.

Alli

ok so you blow a bubble and crease it with a knife. The trick here is to blow a uniform starter bubble so the wall thickness is uniform.

What's a HH lol

A HotHead torch :)

A Hellacious Heathen? :-\"

dj

Mojito is one of my favorites, I make big honking beads, some 2 inches across. I usually always layer it over a core since it's semi expensive.

I know that doesn't help at all, I would just try more heat insurance.

I am sure it is a compatibility problem with the glass but you could just heat it up and heal the cracks and see if it cracks again......
I did a tutorial a LOOOOng time ago. Here is the thread on how to prepare beads to go back into the kiln and heal problems with beads....
http://www.lampworketc.com/forums/sh...g+broken+beads