Why do some boro colors have so much air in them?

[LyndaJ]

Technical question. Why do some boro colors have so much more air in them than other colors?

Amber purple - very little air - nice clear rods, cobalts - nice clear rods, Tequila sunrise, for example, (there are many others) have so much air in them that they look streaky in rod form.

I think - from what I've read, that you have to let the glass sit during the batching process to allow the air bubbles to escape. It can't all be viscosity, because the darker cobalts are very stiff.

Any ideas?

[Jamn!]

I think its the chemicals they have to use the make the color.

[Mr. Meker]

Some glass cant be held at the necessary temoperture for long enough to squeeze and fine the bubbles. You cant get the same temperatures in a crucible of 200 pounds of glass than you can get with a torch a few grams at a time.

Simple colors like cobalt, clear, and plain amber arent affected by long times at relatively lowe temps. AP and similar colors are.

[chayes]

if there is air in a rod it should be considered seconds and not first quality. It's amazing how much stuff i've ruined because of air in "first" quality rods or how many lbs of it i got sitting around here that is almost useless. What ever happened to a thing called quality control. Maybe they think we won't notice. It really sucks when the company tells ya its first quality with a hundred air lines running down the rod and they wont take it back. If you look at the clean cut end of a rod, if there is air you'll see lots of little holes.

[Mr. Meker]

You cant have your cake and eat it too. Some glass has bubbles in it by nature. You either have to work around it or get something else. I have noticed that the tiny bubbles you see in a piece do not show when its cold.

[Firebrand Beads]

You can stir out some of the air in an airy rod, BTW... but yes that is added work.

[LyndaJ]

But my amber purple has no air in it. I wonder if some of it is batch size, maybe larger batches fine out the bubbles better?

[Cosmo]

True, colors like Tequila Sunrise and Purple Luster have bubbles in them. But, the bubbles don't seem to show up in the finished piece, and don't seem to effect how it works in the flame...

[Jamn!]

and then there's lavender... I have an old batch of a blue (NS Milky Way??) that has tons of bubbbles but I sort of like the look in this glass. I haven't seen this color again.

[LyndaJ]

I found this thread over on the GLDG

[chayes]

You cant have your cake and eat it too. Some glass has bubbles in it by nature. You either have to work around it or get something else. I have noticed that the tiny bubbles you see in a piece do not show when its cold.

Yeah if the rods came with air every time i would avoid that particular color knowing the air is there. I have ordered colors that are 100% free of bubbles and then get the same color again and it's riddled with air. Those tiny bubbles can condense into one hell of a problem on large scale stuff. First quality should mean that the glass is held to some kind of standard.

If you were to waste thousands of dollars on air riddled glass, you might agree with me. Buying large quantity's of glass should not be like playing Russian roulette.

[e. mort]

Originally Posted by chayes

Yeah if the rods came with air every time i would avoid that particular color knowing the air is there. I have ordered colors that are 100% free of bubbles and then get the same color again and it's riddled with air. Those tiny bubbles can condense into one hell of a problem on large scale stuff. First quality should mean that the glass is held to some kind of standard.

If you were to waste thousands of dollars on air riddled glass, you might agree with me. Buying large quantity's of glass should not be like playing Russian roulette.

I'm with Chris on this one. I have ruined many a nice marble backing when I went to lay down a nice line of color only to find the rod was full of air. Sure, you can pop the bubbles, and do pinwheels, but what if your design called for nice clean lines? First quality rods means no bubbles!

Unfortunately, all of glass manufacturers seem to have had a lapse in quality lately. I have taken to purchasing small qualities of color, and paying more for it because i don't want to get stuck with pounds of air filled, poorly mixed rods.

[Cosmo]

I think not all of us are talking about the same "bubbles". A lot of GA colors have what looks like thin lines running through the rods. They are bubbles, but got stretched out in the process of pulling the glass down to rod form. For example, I've never seen a rod of Caramel Luster or Tequila Sunrise without these lines/bubbles in them.

Now, if there are bigger bubbles, then yes that may cause a problem. But the type I'm talking about don't show up in the finished piece.

[Jamn!]

I can't complain. I have bought a lot of those "cheaper" rods. I don't do large production work so I don't mind having to mix the glass.

[oldschooltofu]

aside from the colors that naturally contain air (tequila, NS lavender, violet, purple rain etc). the problems chayes are refering to are batch problems or what i call top vs. bottom of the pot.

from what i have learned, the longer the soak the less air. if color companies soak for 1-2 days instead of 3-4 days they save lots on energy but end up with more air in the batch.

the glass pulled from the top of the pot will have more air in it than at the bottom.
unfortunately the color companies dont cull their pots this way....i am sure some of the top of the pot is garbage or seconds, but where are they suppose to draw the line??? the glassblowers want bottom glass, while the vendors need to sell the entire batch. or else they would have demand for only the bottom glass and end up with lots of "airy seconds" on their shelves.

i have been told lots of times by color vendors, if you like a batch buy lots so you have a few year supply. or risk buying a little at a time and you will get 50/50 chance you got bottom or top of the pot. If i like a color or batch i will usually purchase 10-30#s.