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-   -   Boro Help Needed! (http://www.lampworketc.com/forums/showthread.php?t=13714)

KLittle 2006-02-08 4:57pm

Boro Help Needed!
 
When I work with some blacks, blues and greens there are spots where it looks divitrified. However, I don't think it is devit because I can't flame polish it out! What the heck is going on? Is this what is referred to as 'phase separation'?

Any tips/tricks to avoid this nasty outcome? or to correct it? Are there certain colors within the blue/green/black family that are less prone to this? I have no idea what I am doing to encourage it. It only happens in patches. Ugghhhh ... what a drag!

Kari

firefreak 2006-02-08 5:13pm

Kari, You are reducing the color. too much propane. try turning down the propane or turning up the oxy. Turbo cobalt, black, and some of the light greens will reduce to a ugly grey or liver color.

Or you may be burning the color. if little bubbles(scum) are being produced you are boiling the color. Work farther out in the torch flame or work faster.

Either way if you run a oxidizing flame, it should eliminate the problem.

KLittle 2006-02-08 6:29pm

Thanks for your reply! I don't think I am using a reduction flame ... my colors are coming out true and crisp everywhere else *except* those spots! I tend to work more on the oxidizing side to begin with. However, I am running a Lynx on an Onyx+ generator.

Perhaps I should add that this is happening on unencased color ... and not in the form of a bead. I am working off mandrel.

I will watch closer to see if I am burning the color. It is strange because I could have a long swipe of color and only a small patch on it will have this happen!

Thanks again for the input ... other ideas are welcomed!!!

Kari

firefreak 2006-02-08 10:55pm

How long are you working the piece? What brand of glass etc? are you working to color on clear? what brand?

More input!!!! lol

KLittle 2006-02-09 12:56am

Each piece takes me about 45 minutes from start to finish. I primarily use GA rods. Not sure which kind of clear I have been using but yes, I am building my color on a clear core/rod. I try not to repeat the heating and cooling cycle too much because I know that the colors could go muddy. I am getting great color except for these isolated areas!

An example ... I noticed this occurring on areas of some exposed Amazon Night (which look black). I would layer clear over part of a stripe but then once melted in I would let some of the color creep out from underneath the clear and in some places along that exposed line I would get this odd surface that looked like devit. It was a cool effect with the cased part being a vibrant green and the unencased part being black ... just don't want this nasty 'devit' stuff to happen anymore!

When I get to the torch next I will try similar colors again and try to watch more closely when I see it happen in the flame ... maybe I am boiling the color ... I'll watch for it and see.

Thank you for trying to help me figure this out! Just another mystery to solve with this glass ....

Kari

elle 2006-02-09 4:54am

I always have this problem with any green or teal based boro color, whether it is a striking color or not. The teals seem to be worse about this than the regular greens. (In fact, the soda lime aqua/teal colors are prone to bubbling as well.) However, I do not have this problem when encasing, just when the color is exposed in the flame for longer periods. My flame is definitely more on the oxidizing side, and it seems like no matter what I do, it happens anyhow. I just avoid using those colors on the surface now.

For example, I was using GA Teal and it did the phase separation/devitrification thing (not sure exactly which term is correct for this phenomenon) in specific spots, mainly where there was no constant full-on contact with the flame. Like in places between bumpy dots, it would get kind of chalky and bubbly looking, and no matter what I did it wouldn't melt away. It seemd that the places where the flame couldn't get it hot enough was where the nastiness happened. I've also had this problem with NS Glacier Blue, GA Emerald and True Green, but as I said, not as bad as with teals.

Now, if this is happening with black, might you be using the GA Black/Green? I've found the GA Black/Violet to be the best black I've tried, and it comes highly recommended by others. The only problem you may have with GA Black Violet is with dichro - from what I have read, B/V has manganese or magnesium or one of the elements that start with "M", and this will react with the dichro, creating a weird outline where the dichro touches the B/V. Other than that, you should be fine. It's very smooth, and I've never had any pitting or devit or whatever.

:)
Sarah

Mr. Smiley 2006-02-09 5:10am

yep, what she said. Teal carnival is the worst for me... I've had this happen with several colors. It really really sux... but just avoid leaving them on the surface. It seems we all find out the hard way on this topic... but does it have to be a piece I spent a very long time on or is that part just me? :lol:

KLittle 2006-02-09 11:58am

First of all, Sarah, thank you for your response. I knew that I wasn't imagining this stuff! Your post has many good points which are what I *thought* was happening and as I look back ... yes it is more predominant with the blues and greens. The black I used was black green when it happened but I have since switched to Black Violet and had no issues at all. Thanks for the tips on which colors to stick with.

How unfortunate that we just have to live with it and not use certain colors on the surface. Thank you so much for your advice.

Brent, yup, it's not just you ... Never fails that this happens on a piece I have either spent a long time on OR a piece where the other colors really POP but you have this nasty stuff to ruin the whole darn thing!!!

Thank you soooo much for listing some of your worst offenders. I will heed your advice and save myself some headaches!

So, I guess the only thing to do to save these pieces is to sandblast them? That should take care of the nasty stuff ... but I guess it will change the nature of the piece then .... hmmmm.

Thanks again!!

Kari

Mr. Smiley 2006-02-09 4:28pm

Yeperz... blast 'em! :D


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