5% rule: can it work with Boro and soft glass?

[wildwire]

Hi! I assume this is a stupid question but - I have boro tubing to make ornaments - can I use the 5% rule and jazz the boro up with 90-104 frit?

Would it be successful?

thanks, Shauna

[SonyaHusko]

NOPE (if you do, run like he**, that sucker's gonna blow)

[cghipp]

I would love to hear about the death of the so-called 5% rule (or 10, or 15, etc.). There is no such rule.

Aside from that, you cannot mix boro and soft glass. The difference in COE is about 60-70, compared to 5-10 for furnace glasses and Effetre.

It's not a stupid question, because the "rule" is put out there so often, it's easy to see how you might get confused.

Courtney

[luke gardner]

Definitly a huge difference on the coe scale. Way more than 5%. Just checked my TI-80 and it is a 32% difference in coefficient of expansion.

[wildwire]

Thank you everyone! I figured it wouldn't work but was kind of hoping it would!

Thank you, Shauna

[luke gardner]

As a general rule, glass will accept other glass or materials up to 5-10% stiffer than itself based on the coe difference. This means that the material must have a 5% lower coe than the glass that it is to be included in. Thus the minimum coe of a material that is to be included in 104 expansion glass is a material with the coe of 99-94. There is no exact rule to go by as to the exact boundaries that govern coe compatibility, since morettii and bullseye colors work together. I have heard from master glass workers that there are 10 to 15% compatibility difference within moretti colors. From what I have been told, the coe factor between two equall sized masses of glasses is just as relevant as the mass ratio of compatible glass VS incopatible glass.

[cghipp]

Luke -

That's good info, but that's not what peoply are usually talking about here when they say "5% rule." (I hear 15% rule more often, actually.) At some point it became a beadmaking urban legend that there was a "15% rule" that allowed you to use non-compatible glass as long as it didn't make up more than 15% of the bead. Maybe confusion over the rule you're talking about has helped this misconception stick around. Of course, you may be able to use 15% glass of another COE, but there's no hard and fast rule about it from the standpoint of a percentage of the total glass.

I had not heard of anyone having success using Effetre and Bullseye together. Isn't Bullseye 90 COE? Most of the reduction frits and other furnace colors we often mix with Effetre are in the 96 range.

Courtney

Edited to say: There's no hard and fast rule that you can use 15% of ANY COE with another COE glass.

[Cosmo]

The good thing is there are so many cool colors of boro glass available in frit, you can get just about the same effects and all the glass is compatible.

[cghipp]

Another good thing is that, even though boro color is more expensive than most soft glass, a little goes a long way!

Courtney

[Emiko]

Originally Posted by cghipp

I had not heard of anyone having success using Effetre and Bullseye together.

My first beadmaking teacher was somebody who shouldn’t be teaching. She was using Bullseye staind glass scraps to be thrifty (It was before Bullseye started to produce rods.) and was buying pre-pulled stringers because she didn’t know how to make them. She also had some Moretti Filigrana to use with Bullseye. During the workshop, I made a Bullseye bead coiled with Moretti Filigrana. I don’t know where it is now, but when I saw it 2 years ago, which was 8 years later of the workshop, it was still in one piece. A begnner’s luck? Ignorance is bliss?

[MikeAurelius]

I'd love to see the piece under a polariscope, Emiko - it would be a photographers dream pic!