boro checking at <400 degrees

[dmas0n]

Ok so I've been doing a lot of work with the chinese white tube and am pretty much fed up with it - the boiling and shockyness to be specific. I've been looking for a way to get reasonably priced white tubing and to that end I did a vac stack out of borosticks, one of my very favorite whites. I saw the video of Steve Sizelove doing a stick stack with borosticks and knew I didn't have the tool he uses fpr the interior size so I used some 26mm standard wall and a vacuum instead. I put the finished pull into the kiln and started working with it right after it warmed back up - mistake. I made several pieces and all of them checked in odd places with no clear starting point. I "repaired" them and they checked again in the same places. Tending to blame myself first I figured Maybe taking them out of the kiln at 380 caused a problem (though it shouldn't), or that I had done an incomplete repair so I did it again, thoroughly, with a full ramp down and the same result. Now I'm puzzled so I took a little jar I had made with it and I repaired it again and again and again making sure to inspect the repair job. It was small and open enough that I could see both sides of the crack and I could be certain it was completely repaired. It was thin enough that any air bubble would show. Through repeated observation I found that it checked somewhere between 460 and 300 every time, which should be outside the stress zone for boro. I use a rampdown that falls in line with Contemporary Lampworking. I'm no expert but I've done enough vac stacks to be comfortable that I left no air pockets, just in case I broke some of the bad tube down and checked. What else could I be missing??

TL;DR - Why is my borosticks vac stack checking between 460 and 300 degrees in the ramp down?

[aREa541]

Borostix are not the most stable glass ever. I quit using their frit because of serious compatibility issues. I have never vac stacked their rods, but I would be highly suspicious if you are having problems. They use dye to color glass powder then press it into that stick form. It seems like shit is pressed into the glass sometimes that shouldn't be there. They are the only ones who manufacture their glass this way, and it is the same way they have always done it for the consumer electronics industry.

Star white, or Whiteout will do ya just fine in a stack. I use Star White as part of a holy trinity that goes in almost all my stacks.

I personally love china white tube for lower end stuff. I don't find it boils at all on me, although it will develop small "pock" marks occasionally. It really prefers to be completely molten and melted in before working it which will give it a smoother surface.

[dmas0n]

Yeah I suspect you're right. The main reason I chose the borosticks was because of cost though, which makes using first quality color a problem. I assumed because it had worked so well in other applications that it would be fine but I guess this is a case of getting what I paid for.

[hashmasta-kut]

my borostix caveat is glow and dichro side by side. cracked amazingly afterwords, ridiculously.

[Logan]

Chinese white rocks! The problems you are experiencing, boiling and shocking, are both caused by the same thing. You are working it too hot too fast. White likes to be bathed in heat before using any kind of penetrating flame. If you are using it for large multisection pieces dont leave it out of the kiln too long and be very mindful of the heat flow. Especially take your time with welds, this tends to be where the worst boiling occurs. Go slow and work farther out it in the flame.

[dmas0n]

Thanks Logan, you're right about the welds for sure. When it's just a simple piece without much shenanigans I can make the Chinese white work by babying it as you said but anything more complex and the area around the welds ruins the piece. I will try your suggestion about giving it more frequent re-heats in the kiln.

[kq9ak]

I find with borsticks and china white, in vac stacks it helps to let it hang in kiln at 1050 before using,let it off gas.

[menty666]

One thing with the borostix is that occasionally there's still traces of the refractory material the molds are made from attached to the sticks. It can cause problems. You might try giving them a good scrub before attempting another stack.

[LooseSeal Baller]

if your color is boiling wether its white or whatever you should try turning your propane down to 5 lbs pressure. ps i have used boro white and china white never with problems cracking. sounds like the glass isn't relaxed enough. if its a boro-barf stack could be difficult to see if there is air trapped under color, assuming the color is sandwiched between clear.

[HomegrownGlassStudio]

Learn a good annealing flame and keep that bad boy warm...

[Aymie]

Don't put a tube on the inside. I have done an all white pull without issue, and seen one done with all flow stix.

The borostix have never been mixed. They are pressed powder, fired in the kiln. I remix them for everything but tube pulls.

My theory is that having an open inside gives a little wiggle room for expansion, rather than being trapped in clear.

Also, trick for tube pulls with boro stix: put the last bar in upside down. They are actually more of a trapezoid than a square and the last bar going in upside down fills the gap and sort of locks everything in place.

[LooseSeal Baller]

have seen it done both ways without cracking problems. just needs to get hot enough and relaxed.

[dmas0n]

Aymie I read you're the queen of boro bars so I'm glad you chimed in and appreciate the suggestion. I did several vac stacks before this white one with very mixed results. I will try another one sometime when I can get my hands on one of those tools or make one myself. What OD tube do you use? I was using 50x5. Any colors I should avoid? Eggplant seemed problematic in other attempts. The boro bars are pretty much my favorite white and I was way stoked about the idea of being able to make them into tubing as they are extremely cost effective considering their quality. The tube looked nice and the piece I made out of the one pristine section looked nice as well so I hope I can get it worked out sometime.

Barry I don't guess I know what you mean by relaxed but It was heated through to the middle. I broke a chunk of the offending tube open to check for any possible air pockets and found none. Of course I could have missed them but every suspiciously cracking tube pull I made when I first started learning how showed me why it cracked when I busted it open so I don't know what else I can say about getting it hot enough... As for the china white, I know it needs to be pre-warmed (is that what you mean by relaxed?) but even then for welded areas or areas that need heavier work it's extremely fussy and makes me the opposite of relaxed. My preference would be pulling my own (cost effective) tube for anything more heavily worked than a spoon.

[LooseSeal Baller]

thats not what i mean by relaxed . basically what i'm trying to tell you is no matter which way you make the stack that is if it has clear on the inside or not if its all melted in and pulled down to a thinner piece of prep work it should be relaxed enough to bench cool without a kiln! I do it myself all the time and watch others do it as well. the china white i've used doesnt need to be warmed up either. unlike the other china colors the white is really buttery

[dmas0n]

I pull mine down to about 22 mm, best as my arms and eyeballs will allow. I neck it down and break it into 4-6 inch slugs and pop it in the kiln. I work what I need to work out of the kiln and let the rest anneal with whatever work I've done. I suppose I should know if it bench cools well or not but I don't because I prefer to be safe on expensive color.

If you explain to me how I can achieve this state of relaxation, preferably in ordered steps, I would be happy to try it but for now I still don't know what you mean exactly.

[LooseSeal Baller]

not really about the length, its more about wall thickness and how even that is. not sure what your trouble is try making a small piece and bench cool that? like a prep ball or something.

[Aymie]

I use 50x5

Do not use black, ivy or kelly...ever...for anything. Extremely hostile colors.

[LooseSeal Baller]

yeah those are very hostile colors, but i have seen them used in stick stack prep before. My teacher did it, not saying he had the best time but he made it work. The boro-bar white on the other hand is a great color, other than being slightly off-white in color, it works great no boiling or cracking problems from me.

[dmas0n]

I'll make note of those colors before I try again. Thanks.

[Aymie]

They aren't all hostile.

[LooseSeal Baller]

you say dont ever use black, kelly, or ivy. then when agreed with, you reply "they aren't all hostile." I think you are confusing me and others.

[Aymie]

I was confused. I thought you were saying all of the boro stix were hostile, rather than agreeing with my post above. Sorry dear.

[duh]

I gave up on the borostix white because it loves to check under clear IME.

[LooseSeal Baller]

no boro white kicks ass i repeat it kicks ass no cracks yo. zip zero

[Aymie]

http://www.talkglass.com/forum/showthread.php?23815-Elan-Origins-Borostix

I have never had white crack. Winter 2009 the flow has a picture of an all boro stix tube pull. Can't upload the damn pic.

[Big Jay]

I've never had borostix white crack either.

[duh]

Maybe it's just me, i've only used the frit. And a few times it didn't start checking until a day or two later. (Garaging @ 1000f, annealing @1050f)

I just looked at the pieces that I had problems with, and it's really weird.. Pure white frit is good to go, but anywhere that white touches any other color frit (top/bottom doesn't matter, just touching in anyway), it just checks to shit... Is it possibly just hostile when used with other colors? The frit is definitely melted in and it has checked when mixed with peacock, amber purple, green exoitc, or blue moon. However I had one that was mixed with GA Red Crayon frit which did not check.... Any ideas?

[Big Jay]

check your batch. Something seems to be wrong. I haven't had compatibility issues with those colors.

Is there a chance your pyrometer is off? The reason I bring this up is I had a problem for a while with random stuff cracking, come to find out my digital was off by a couple 100 degrees.

[Aymie]

Any of the frit goes to shit unless you use pink as an in between from boro stix to other brand.

As much as I love the colors, I rarely use the frit.

[TlkQ]

I use carribean blue boro bar frit constantly and mix it with everything and have never had a problem. Only boro bar frit I use.

[neddowerx]

So I just ordered 2lb's of white borostix, I mostly wanna use it for eyes, and overlaying ontop of clear to make solid color vessels. So I've been having problems with Chinese white used for the whites of my eyes cracking my pieces, even while hot. And also cracks pieces after cooling? I know there's certain stress related to how the eye lids and such arrent melted smoothly on the eyes for realism, but only have cracking issues w China white. I was truly hoping that white borostix didn't have these issues!:(

[Aymie]

My bracelets use the white (and all the others) with extremely acute angles in my surface work, you will be fine.

[dnug42]

you can use graphite rod instead of clear tube to rap color on as well...jus a thought if ya didnt want to use clear tube under...