Bubble, Bubble, Toil and Trouble.....

[tiggybubba]

Hi everyone.

I have a question that I just know that an expert out there can help me with.

Here is the scenario.....I am making a long barrel and as I start heating it and getting ready to marver it into shape, I am getting tons of bubbles coming up and popping. White and Ivory seem to be the worse culprits but it can happen with any colour (opaque).

I am on a HH (if that makes any difference) and would really like to learn how to avoid this or worse case scenario, how to fix it once it does happen.

Thanks
Leslie

[Venessa]

What kind of bead release are you using? I have had problems with BOM, and I know there was a thread about it at one time. If you don't get the release hot enough before you begin to wrap your glass on, it will bubble.

[Chuckie]

That's the same thing I was going to ask. I know if I don't dry my release properly or heat it well enough before applying glass, I get bubbles, too.

[Lisi]

I've had that problem with larger mandrels and ivory, and can't figure it out still. The release was fully dry, but maybe not. I wonder if it is caused by moisture in the release?? This stuff when it's dry could still probably pull some moisture out of the air.

I would think getting the mandrel hot enough would take care of that trouble. I hope someone has an answer to this!

[tiggybubba]

I was using bom, now I am mixing bom and foster fire as the bom was peeling off the mandrel far too often.

[meadowesky]

I have the same problems some times but I think it could be due to how you wrap your bottom layer of glass on. If you wrap against the previously placed glass and leave any space at all you Will have air there that will want to escape.

[LoriGreenberg]

I get the same thing with BOM if I don't heat the mandrel enough before applying the glass. I don't think it has to do with moisture, as I live in AZ and we don't know what that is here.

I have a theory though...I've noticed, on the glass that is clear when molten and you can see down to the mandrel, that the bead release forms micro cracks when you put the initial wrap of glass on and somehow that creates a little bubble that then expands. Maybe there were already tiny cracks there and air was trapped and then expanded with the heat? Often it appears where one wrap is next to the other. I used to think I was trapping air between wraps but I know it's not that. Then I saw bigger cracks in the release (still not big enough to make the glass stick to the mandrel) and a big bubble formed on it.

Not sure if that is what happens but it sounds good, doesn't it?

Try wafting your mandrel through the flame until it slightly glows before putting on the molten glass.

[monarae]

I have the same problem and it only happens when I'm making long beads. I use dip and go sludge, but I don't think mandrel heat is the problem.

The difference between making a round and a long bead for me, is how I wrap the glass on the mandrel. I make a series of small spacer type beads, always touching at the base. However, if my wraps are not wide, they create a space that traps air. It also happens when I make two end spacers and fill in the middle.

How do I solve it. I snip into the air bubble with my scissors and melt slowly from the other side, causing the glass to pull away from the void on top and fill in the void from the sides and below. It isn't easy, and it doesn't always work. When that doesn't work I melt the heck out of the glass where the bubble is, and try to pop the bubble. When that doesn't work I press the molten glass on the marver, and roll it around the bubble to squeeze out the air.

What a pain!

Mona

[DesertDreamer]

I'm thinking the mandrel hasn't been preheated enough. I've had that happen when I start with a heated footprint that's too small (because mid-wind I lose my mind and decide to make a longer bead). It could also be that your rod had some lines of bubbles in it. I've had that happen several times, especially with Vetro white, but I've encountered it with several other colors over the years.

[Palestrina]

Lori Greenberg is absolutely right! I've been working to figure this out and came up with the exact same thing. Not really cracks though, it seems to just be the texture on the mandrel and something in the release.

I've been using BOM for a while. The first batch I got NEVER did this. Now, I get it pretty much every single time I want to make anything other than a long bead. It's definately not my wraps and it's not the rod. Also, I DO heart up my mandrel to red hot rather than glowing to try to avoid it but it just doesn't always work. It's the release. I mixed it with Foster Fire (50-50) and the problem got much better but it didn't totally go away. Still, I love the stuff so much I just bought 16 more ozs. of it.
Which reminds me... anyone got any foster fire for sale? I thought I ordered it, but I guess not.

[debkauz]

The only time I get bubbles is when I'm sloppy about doing the wrap on a long bead. It does seem that the softer the glass the more chance it will happen. Maybe they really are in there but just surface easier on the soft glass.

[ZingZ!]

With transparents and whites/pales I find that if I get the glass too hot too fast it's bubbly before it even touches the mandrel. Could be excessive thermal expansion and/or metal oxides reacting a bit, but that's just a guess.

Generally I get the least bubbles by flaming the release really well everywhere glass is going to end up (i.e. glowing the release and mandrel all the way around) then applying the first layer of glass a bit on the cooler side. This combination normally prevents "mandrel puffer" bubbles, which leaves only those I manage to trap in there myself while wrapping.

Recently I've avoided trapping in bubbles by just laying down a honkin blob of glass and pressing harder in the center to spread it a bit, then flowing and marvering it into a tube of the desired length. Once that's done I fatten it up as needed by wrapping on another layer of glass over the first, and adding a little extra wrap at the ends if I need to doughnut them up a little better.

John

[LavenderCreek]

I have this same problem more often than not. It drives me nuts so I've also been trying to figure out what is causing it. Here are the things I find that bring up the most bubbles.

1.Not heating up the bead release/mandrel enough before beginning.

2. Heating the rod too hot, too fast too close to the tip of the torch. If you watch when you do this, tiny bubbles build up in the molten glass on the rod, which you wind on to the mandrel and which expand.

3. Sloppy initial wrap trapping air.

I think what Lori was saying about the fine cracks in the bead release causing a problem makes alot of sense too. I think some bead releases are more prone to causing bubbles than others. I don't remember ever getting bubbles with foster fire, but I still much prefer BOM, even with the bubble problem.

I really think it mainly stems from the bead release; gases, cracks, moisture, etc. Because it usually only happens during the initial wrap. Once the foot print is down, you usually will not develop more bubbles, unless you are just cooking the heck out of the glass.

Some colors are definitely worse about developing bubbles than others.

[Anne Londez]

It usually comes from not heating the bead release enough while putting on the first footprint of glass. Heating the release releases some gases (you can actually use that when blowing up a hollow bead) and if you don't do it properly you get bubbles when the glass is hot enough. The reason I think it happens more often with ivory and white is that they are softer colors, easier to overheat to the point where bubbles will rise easily to the surface.
I always tell my students to have the mandrel dark red hot when the first coat of glass touches it.

[monarae]

I didn't think it was the cause, but I take it all back. I've been heating my rods to a glow before I even melt my glass. Then I make sure that the next spot to receive glass gets heated as I lay on my long bead. No bubbles, at all, not a one, not ever, anymore!

Mona

[tiggybubba]

made several long beads today and really paid attention to two things, getting the mandrel hot and not trapping any air. not perfection but certainly better. Also am using a mix of BOM and Foster Fire now. Still having trouble with the release peeling away from the mandrel on the ends tho....not sure why. Not pulling on the glass at all it just peels away. AARGH!!

[Feldt's Glass]

If your mandrels are new you might try rubbing with sandpaper. I do this on all manderels and it gives them just a bit more hold. I also mix bucket o Mud with the foster fire. I have found at least here that if I don't let them air dry I have many of the issues you mentioned. Don't know why I just let them dry for about an hour before I start and I don't have those issues.

[glass-diary]

You were working too hot?