What happened here?

turtleshelle · #1 2009-04-22, 4:05pm

Hi all,

I've been crazy busy getting ready for a show. This is my biggest marble to date-about 1 7/8". I used Citrus Grapefruit for the rose and Plum Kush as a backing color. I covered the Plum Kush with dots of clear, then put dots of Citrus Grapefruit over the clear. When it came out of the kiln it was all crackly on the back

. Kind of a cool effect but I want to know what happened here-is it incompatibility with one of the glasses or did I possibly not anneal long enough? Can it be fixed? What do you all think about leaving it crackly and making it into a larger art piece-like perhaps electroforming something around the back so the crackly look can be seen through the lens. I appreciate your feedback!!

ginkgoglass · #2 2009-04-22, 4:32pm

The only time I have had something crackle is when I accidently picked up a soft glass rod of clear. It crackled like a windshield after a front end collision!

I can't really see the crackles on your pic so I'm not sure that's what it is.
Pretty Marble though!

Bunyip · #3 2009-04-22, 4:49pm

That's checking and it will destroy that marble in time. Those sharp edged cracks are an indication that there is probably some incompatibility. Maybe the backing was too thick. I've had similar issues with NS unobtanium. Maybe the sparkle plays a part?

Bobeche · #4 2009-04-22, 4:53pm

I've had that crackling with unobtanium also, but not with either of those colors.....?

turtleshelle · #5 2009-04-22, 5:25pm

trying to figure out how to make the image larger so you can see the crackle. Not really working-is it?

Bunyip · #6 2009-04-23, 5:59am

I made a piece with unobtanium backing last night. a VERY thin coat. Yeah. It checked up on me. It looks fine on the surface, but that calls into question any piece with unobtanium in it...if the surface looks fine but there are hidden cracks that is a bad situation.

..and I blame this thread for causing it. Ok not really, I knew better.

Cosmo · #7 2009-04-23, 6:04am

I have never had the first problem with Unobtainium. I use a LOT of it. I have even used it encased, and I have one that is 3 years old with Unobtainium inside it and it's fine. Same with Loch Ness, Moss, and the other NS sparkle colors. For some reason, GA's sparkle colors don't seem to work well encased, but Northstar's seem to work fine for me.

I have always heard to work it in an oxidizing flame, which I do, so that may be the issue.

Cosmo · #8 2009-04-23, 6:05am

Quote:

Originally Posted by turtleshelle

trying to figure out how to make the image larger so you can see the crackle. Not really working-is it?

Are you talking about the "cracks" you see when you look through the inside? If so, those are probably bubbles, not cracks. If you don't work your color hot enough when you put on your background color, you can get long thin bubbles that look like cracks.

turtleshelle · #9 2009-04-23, 6:25am

Thank you all for your insight!! I am referring to the cracks in the background-behind the rose. There is obvious cracking between the clear and the Plum Kush when you look at the back decoration. When you look through the lens, the background is irredescent with cracking-kinda cool-but flawed non-the-less. I was wondering why Plum Kush might react that way with clear. I didn't think it had any issues being encased. Could it be that because it is a large marble, perhaps it was not annealed long enough?

I too have issues with unobtanium. When I mix it with clear, that seems to resolve my problems but it waters down the color.

Can anyone advise me how to post a larger sized picture? That should help you all see what I'm talking about.

Again, thank you all so very much for your help. I LOVE LE!!

Cosmo · #10 2009-04-23, 6:52am

I'm still tempted to think it's not actually cracks. I've seen many, many marbles with what you describe. When I teach marble classes, most of the students make a marble or two that look like that. I still think it's long, thin bubbles. If you can post a close up or a larger photo, we can say for sure.

Plum Kush shouldn't react with clear any differently than any other color. I have never heard of compatibility issues with it.

If you can't figure out how to post a larger photo, e-mail it to me at chad@cosmoglassworks.com and I'll post it.

Bunyip · #11 2009-04-23, 6:59am

Cosmo, I remembered what you had said before and tried to do exactly that. My piece was a pendant, I backed it like in your frit implosion pendant tutorial. Maybe I didn't heat the unobtanium enough? The only other thing I can think is that I put dots of triple passion over the unobtanium, maybe that did it... I was thinking of reheating it molten to see if the cracks would go away and then trying to re-anneal with a long hold at 1050 and a very slow ramp down, but my annealing program is pretty conservative anyhow for this type of piece so I don't have high hopes. I'm going to do some testing tonight backing a couple clear maria in some different scenarios too. Another possibility: Maybe what I think is unobtanium is something else? It's frustrating to lose an hour's work...

chelle: in your graphics editing program (photoshop etc) crop images to the relevant portion. Then check the pixel size of the image, and resize so that no dimension is greater than 640 (but preserve the aspect ratio or it distorts the image). Finally, save as jpeg and in the compression dialogue box it should show you the image file size. If it is greater than 80 kilobytes, decrease the image quality until it reaches 80 kb or less. If you're not able to edit the images yourself PM me and I'll see what I can do to help.

ginkgoglass · #12 2009-04-23, 7:03am

I haven't had problems with Unobtainium either even encased. You can see the two bands on the left of this heart.
I wonder what the difference is.

wickedglass · #13 2009-04-23, 7:59am

I've heard people talking about the sparkly colours not liking to be encased but personally haven't had many issues with them except once about 2 years ago when I imploded milennium moss and it cracked on me. Never any problems with surface application, though. It's not really surprising that such problems should arise, as the aventurine-like colours have a heck of a lot of metal in them. However the Plum Kush I did have major compatability issues with, again I used it many years ago, everything I used it on cracked due to incompatibility. I've heard people talking about the sparkly colours not liking to be encased. Sorry to disagree, Cosmo, I know the air lines you're talking about, but those cracks don't look like air bubbles to me, the edges look too sharp and angular and it looks like there are definitely refractive flat planes in the back of that marble.
The thing to remember is that colour is made in batches, and a slight variation in the component chemicals may effect a slightly different COE. When I was in the 3rd and last year of my BA degree I was using a particular kind of yellow in my work (I was using Kugler colour and working from a furnace). All year it was working fine, with no problems. Towards the end of the year when the folio was due I ordered a bunch of more yellow to make my final folio work with and bam, every single piece was checked ... but only in the yellow parts... same yellow, different batch. It caused me no end of stress (no pun intended)!
So when you get your boro colour, you're not guaranteed to have the same batch in every bundle, either. I've had a particular northstar colour before (teal) and had slightly different colours through the bundle. Some sticks worked absolutely beautifully, but some were completely unworkable and got a boiling reaction (like when there's too much flux in the batch) in them even at a sedate temperature.
I have a feeling that PK has a lot of manganese oxide in it and it may be one of those borderline colours which are just compatible and if the mix is slightly off it pushes the COE just that wrong side of compatible. So if you've been using Plum Kush before with no previous problem, then it might be that the stick you used on that particular marble could have been slightly off COE due to a slight variation of batch or because it came from a different part of the furnace.

Bifwitsis209 · #14 2009-04-23, 12:37pm

how long did you work the back side between heating the core ......i have had that happen to me between layers of clear before......... while tryin to strike my implosion before......

Hels · #15 2009-04-23, 12:52pm

Maybe you worked it with a bit too much reduction? I know some of the glass manufacturers say that you always shoot for an oxidizing to neutral flame while working the glass, then reduce at the end... because by bringing the metals to the surface, you are CHANGING THE COE... then you encase that CHANGED COE...

Of course, this is easy to say and hard to do, especially if you're on concentrators, where every now and then it will put out a 'puff' of not sufficient oxygen, and boom, there come the pretty reduction colors (haze), and it's not in your control. The longer you work one piece, the more this is likely to happen in my experience. Maybe you trapped a patch of serious reduction in there that caused incompatibililty?

You have a lot of reduction going on in the Momka Citrus Grapefruit. That happens to me on larger marbles too, which is why I gave up on silver colors (for now) in marbles.

Are you on tanked oxygen? I think tanked is the way to go if you want to implode silver colors in marbles based on my own equipment. I don't get cracking, but I don't get the amazing colors on marble implosions either

.

rg9403 · #16 2009-04-23, 2:26pm

what is your annealing schedule for this marble. When you go that large with certain colors like unobtanium a very strict annealing is neccesary. Unobtanium can cool a bit faster than clear glass.

turtleshelle · #17 2009-04-23, 3:43pm

WOO HOO!! Thanks all for your help on picture re-sizing!! The anealing schedule was garaged at 1100 F, ramp down 100* an hour to 950F, hold 1 hour, the ramp down 400* an hour to room temp. That for my smaller boro marbles-didn't expect this one to be so huge and forgot to adjust schedule accordingly.

I work with tanked O2 on a phantom. I try to keep it oxidizing as much as possible but it is possible it got reduced.

I never thought of how long it took to work on the back before flashing the front. That could also have been the cause.

I'm thinking of re-heating it, swiping off the background, and trying again. Didn't realize the thickness of the background could cause issues.

Thanks again everyone!! I'm glad I'm not the only one who seems to have issues with Plum Kush so far.

Bunyip · #18 2009-04-24, 5:49am

I have two different colors labelled "unobtanium". One is grayish-green, the other is dark blue-green...I wonder if that is the problem, I've been using the dark blue-green one and that's the one that has been giving me problems.

ginkgoglass · #19 2009-04-24, 1:38pm

I'm thinking maybe that the whole piece needs to be carefully brought back up to the same heat base before putting it in the Kiln so everything can relax a little bit.

Could the problem be uneven cooling and heating? This may not be a problem with "regular" colors, but with the high metal ones it may be more of an issue.

ginkgoglass · #20 2009-04-24, 1:51pm

Silver Unobtainium is more greenish, Obtainium and Super Unobtainium are Gray and Unobtainium is more blue.

pjmarchwinds · #21 2009-04-24, 6:03pm

that looks like you hit it with the flame when the marble was not hot enough, even when you are fire polishing punty marks the the marble has to be smokin hot. any time you go back to heat something up you must make sure the heat base is deep not just a surface heat

J.Meader · #22 2009-04-26, 1:00pm

My guess is the Plum Kush, this color has chrome in it and hates to be encased. I have had this same issue several times trying to encase that color.

turtleshelle · #23 2009-04-26, 7:03pm

I think I agree about the Plum Kush being the culprit. I haven't seen anything about it's dislike of encasement before I tried it out. Now, everything I have made with it, cracks. Could be a bad batch or just a moody color. Thank you everyone for all your insight!! I have adjusted my annealing program and I will be more mondful of the heat base in my marbles from now on!! I love LE!!