what are the different types of glass?

[Samyel]

Bear with me here, I'm a novice. I have a few questions. Okay, a lot of questions. Please tackle any and all.

My primary question is pretty simple, but casual googling has failed to provide and answer. What are opaline and alabaster glass types? I work with transluscent and pastel, and have probably seen the other types, but I don't know what qualities they have or how to recognize them.

Also, I keep seeing reference to "special" colours, like on the Moretti Canada site. What is a "special" colour? Does this relate to its reactive qualities? Does this mean its limited edition or rare?

And what the heck does striking mean, anyway? I understand that the colour changes, but can you control it?

For that matter, what is reduction frit? I thought it was the stuff that made the bead pick up a metallic gloss when you removed oxygen from the flame, but when I bought some, that wasn't what it did.

Another question--I've met evil devitrifying purple, and have noticed my pink (I think it's powder pink--sort of peachy coloured) turns white in places. My dark sky blue goes a weird dull silver near the mandrel and on the base of dots. What other 'trick' colours am I likely to run into? Most online stores don't come with warnings, like "oh by the way, this purple needs to be encased or you'll cry."

As a bonus, what's the deal with boroscillicate? I noticed that it has a very very low COE compared to my Moretti 104 stuff, but that's all I know about.

[alexm]

Bear with me here, I'm a novice. I have a few questions. Okay, a lot of questions. Please tackle any and all.

My primary question is pretty simple, but casual googling has failed to provide and answer. What are opaline and alabaster glass types? I work with transluscent and pastel, and have probably seen the other types, but I don't know what qualities they have or how to recognize them. Opalino and Alabaster are translucent glass from Effetre (Moretti). They have a COE of 104, but there have been compatibility issues with them in the past. Some people say they are compatible with the rest of the Effetre line, others say they get cracking. Compatibility issues aside, I like them because the translucent glass has a luminous quality about it and the colors just glow. They can be hard for a beginner to work because you get a lot of bubbling if you overheat them.

Also, I keep seeing reference to "special" colours, like on the Moretti Canada site. What is a "special" colour? Does this relate to its reactive qualities? Does this mean its limited edition or rare? The special colors are just the yellow, orange, red and coral opaques, plus rubino transparent. I'm not sure what's so special about them, I think they are made with different colorant. Use them just like any other color. They do react with many of the copper containing colors like turquoise, sky blue, copper green, etc. by forming a thin black line at the boudary of the special color and the copper containing color which can be used as a design element.

And what the heck does striking mean, anyway? I understand that the colour changes, but can you control it? Striking means that you only get the right color after you cool and reheat the bead. For example, the red transparent looks amber in the rod. After cooling and reheating briefly it'll turn red. So you want to do this after you are finished decorating your bead right before you put it into the kiln because reheating after striking will cause the color to unstrike. Some colors are notoriously hard to strike, for example, tongue pink, powder pink and silver pink. One foolproof way to do it is to take the bead out of the flame and let it cool thoroughly. Since the color of glass is a very good indicator of temperature, I hold the bead under my work surface where it is dark. Wait until you no longer see any glow in the dark, don't worry it won't crack. When you no longer see any glow in the dark, place the bead in the back of the flame and give it a quick rotation or two. As soon as the color changes take it out of the flame and pop it into the kiln. Be aware that any color change indicates the strike is complete. Some colors like powder pink strike to a tan color in the flame, but upon cooling will be right color, so don't keep restriking it thinking it should be pink.

For that matter, what is reduction frit? I thought it was the stuff that made the bead pick up a metallic gloss when you removed oxygen from the flame, but when I bought some, that wasn't what it did. Reduction frit is crushed furnace glass. It is saturated with metals that will come to the surface in a reducting flame and take on a metallic sheen. It takes a little bit of practise to get it metallic, and some colors are definitely easier than others. I take the bead out of the flame, turn up the propane (or you can turn down the oxy) and give it a few quick turns in the reducing flame until it turns metallic. If you are on a Hot Head torch you will want to make an aluminum foil collar that you slide up to cover the air holes to make the flame more reducing. Remember to use tweezers to do this, the torch is HOT!

Another question--I've met evil devitrifying purple, and have noticed my pink (I think it's powder pink--sort of peachy coloured) turns white in places. My dark sky blue goes a weird dull silver near the mandrel and on the base of dots. What other 'trick' colours am I likely to run into? Most online stores don't come with warnings, like "oh by the way, this purple needs to be encased or you'll cry." The purple aka evil devitrifying purple (EDP) is a wonderful color as long as you understand how to work it. It will devitrify (turn matte) if you take it out of the flame, let it cool, then reintroduce it into the flame. To get around this you'll want to finish all your decorating (don't worry about the devitrification while you decorate), take the bead out of the flame and let it cool slightly. Then reintroduce it into the hottest part of the flame (but not too close to the orifice if you are on a HH) and heat the surface until it melts and turns shiny again. Be sure to direct the flame towards the mandrel to chase the devit away there too. Take the bead out of the flame and keep it out. Putting it back in again will cause the devit to return and you will have to do the melting again. Your powder pink is a striking color. See above about striking. If you strike and then reintroduce it into the flame it will unstrike and you will have either a totally white bead or one with patches of white. The sky blue reduces easily, which means the metals in the glass come to the surface (the same process applies to the reduction frits, but they have more metals in them and the reduction will look more metallic). Don't worry about it, just continue on and anneal the beads in the usual way. When the beads are cool, soak them in Coke (regular not diet) for a few hours to remove the reduction on the surface. Other colors that do this: turquoise and dark turquoise opaque, sky blue and copper green.

As a bonus, what's the deal with boroscillicate? I noticed that it has a very very low COE compared to my Moretti 104 stuff, but that's all I know about. Borosilicate or boro for short is an entirely different kind of glass. You will need a medium to large oxy-propane torch to work it because its melting point is higher than Effetre. It's the same kind of glass that Pyrex is made of. Boro is fascinating to work with. It's much harder and the colors are hard to describe if you are not familiar with boro. I work with both hard glass (boro) and soft glass (Effetre) and I love them both.


Hope this helps!

[Samyel]

Wow. Thank you very very much! :)

[essiemessy]

Came across this thread in a search re opalinos turning really dark, which is what's happening with mine.
The coke hint is being tested as I type :-D
Thanks for the info - never too much of that, particularly since everyone has a slightly different take on issues, especially the things about which to relax :lol:

I made beads with Yellow Opalino yesterday, which turned green while it was melting, but is now a really yukky dark brown. I used a cherry red frit to decorate, hoping for a nice red/caramel, but noooo.. blacky brown. Will be interesting to see what it looks like when it's been sent off for annealing.
I have pink (which turned out a browny pink, which wasn't too bad, but when it got back from batch annealing, it was a darker brown), the yellow, and also I've bought some Carnelian, Med Turquoise, Dark Turquoise, and one I forget the colour of.
Maybe I should leave these until I upgrade from a HH, too.

[Kalorlo]

You should actually be able to work the opalinos more easily on a HH - they don't like getting too hot. If they go black or brown you've burnt them.

[essiemessy]

Well and truly! :lol:
http://i95.photobucket.com/albums/l142/gertthesquirt/Beads/IMGP1158.jpg