Copper / gold / brown aventurine

[Art Freas]

Some one brought us a piece with what looks like a metallic copper colored aventurine frit in the piece. We are not sure if it is a copper or gold or brown aventurine. Does anyone know a manufacturer that does copper aventurine? Thanks much

[Pete VanderLaan]

True aventurines are made in pots only and broken up when cooled. The only true aventurines are chrome and copper. Chrome is not that difficult to make but the copper is far more elusive. I don't know of manufacturers of the product although a lot of stuff is being done with a mica now but it's not the real deal.

[Sky Campbell]

I see a lot of that sparking copper color in Chinese imports. They seem to really love it.

I do think most of what I see is mica.

[Kenny Pieper]

Olympic has aventurine.

[Art Freas]

Pete, thanks that really explains it this was definitely a copper based aventurine. I have used the chrome based but had not seen the copper before.

Kenny, thanks for the steer to olympic. We have looked at the frit there and they have a gold aventurine that seems close but it looks to be chrome based.

[Greg Vriethoff]

The aventurine at Olympic is made by Reichenbach.

Kugler also makes it, and you can get it here.

I think those are the only two commercially produced gold aventurines that are made for our purposes. I don't have any opinion on which is better, nor can I vouch for how well they fit with whatever else you throw into your glass.

Spectrum produces aventurine in black, blue, and green, but I believe those are chrome. They are tested at 96.

[Michael Ahlefeldt-Laurvig]

Yes, I have both the green and the copper- the green can is marked Riechenbach, but the other is only marked as copper. These are maybe 10 years old so it may not be up to date.

[Pete VanderLaan]

Until someone can definitively prove to me those other colors are true aventurines, I'm sticking to my story that chrome and copper as the only true aventurines and keep in mind they are going to be pretty cordy and if blown out too thin, pretty ugly. To reitierate for those of you that don't know the process, the glass is melted in a pot and then the pot is shut down and cooled. The crystals form between 1700 and probably 1400F in the pot. The pot is then taken from the furnace and broken. The glass is salvaged as chunks, not rod. You aren't going to get any rod. Being a pot vendor, I do like the part about breaking the pot. Pure goosbumps.

One of the things that has struck me in color making is that you would think you could take something like a chrome aventurine green and add cobalt and get a different color, or to do similar things to the copper stuff. Invariably, the addition of that saturation colorant really messes with the crystal forming capacity of the pot glass itself. I have found that in trying to Make Mark Peiser's high density opaque titanium alumina magnesium silicate. If left alone, it is the single densest glass I have ever seen in my life and Scott Benefield and I were able to slightly adjust the expansion of it to where it fit a 96 but it is hopelessly unreliable when you do try to do that as Mark acidly points out in his paper on that subject which I read and reread. We just nudge the expansion, just nudge and it goes amber transparent and then blows out the pot.This glass is 11 percent alumina! I really want this glass since it has such enormous potential in the filigrana trade. Good luck making it, and good luck making the faux aventurines as true ones. Glass remembers everything you ever do to it. Keep in mind that there are vendors everywhere and even more in Seattle that will tell you what you want to hear.

[Greg Vriethoff]

FWIW, the gold and the blue are only available in chunk.

[Tom Fuhrman]

the Italians have been making both for a long time. I don't know of any of them that sell and market it for use other than their own. I have a feeling if it is used with high expansion lead glasses there is a better chance of getting it to fit and remain intact.

[Dave Bross]

I bought it years ago from jewelry suppliers as the chunks.

Very high lead content. It would "fit" an amazing range of glasses without cracking/exploding from stress due to mismatch.

All the old time formulas for it are VERY heavy on the lead.

[David Hopman]

I have a kilo of the Kugler gold adventurine #1 frit and a kilo of the Kugler blue adventurine #1 frit. Neither is compatible with any of the batches that I have used.

[Michael Ahlefeldt-Laurvig]

It is compatible with glasma

[Pete VanderLaan]

GLASMA what? There are lots of GLASMA's

Chrome is almost always a real refractory problem child and worth avoiding. Copper stuff on the other hand tends in the opposite direction and makes for some very strange runny glasses with bizzare viscosities. I think some people go out of their way to get into difficulties.

[Art Freas]

Went to see Lino work today. There on the color table taunting me was a 2-3 kilo chunk of gold aventurine.

[David Patchen]

Uroboros sells a green avventurine that's 96 COE/LEC. I've used it successfully with Spruce Pine. But be careful--it's easy to make stuff that looks like a bass boat/1970s motorcycle helmet.

[Michael Ahlefeldt-Laurvig]

Right- I should have said Glasma #33. Ive used large amounts of #5 and 33 and to a lesser extent 22 and 3? and as Ive mentioned before color compatibility has never been an issue for me except with cad reds and yellows. One time an issue with opal white making small things. I only use german colors. Its very seldom discussed over here and if it is then its usually someone having run into a odd batch of color that causes problems, but its extremely rare to hear about and if anything it has gotten more seldom over time. Quality has gotten much better over the years.
I crack off and saw a lot of things and it would show itself immediately if there was strain.
Over the whole of my time blowing Ive only had 2 or 3 pieces come back to me inexplicably broken, and I cant even then point to blaming the color. Ive just written it off as odd things happen or the customer has done a hot- cold wash or something and wont stand up to making a mistake (or not understanding it)
In all honesty- Ive never had the green in production- its very dense/dark color and not at all as sparkly as the copper.

[Pete VanderLaan]

Most of the German colors contain lead with what I now understand to be a new grouping from Reichenbach not having it. The lead allows for quite a bit of tolerance with viscosity differences when matched to most clears in the 96 range. Cadmium glasses will not color well in the presence of lead ( this is an understatement unless you like shit brown) so they have to be made in zinc potash base glass which doesn't have those tolerances built in. As the EU continues to tighten the noose on toxic chemicals that can reach their landfills, I have to wonder what will finally become of the lead in color rod issues. Waterford simply left Ireland after the lead prohibitions set in for decanters and tableware.

Lead is prohibitively expensive in this country now and production of lead monosilicate has simply ceased. The monosilicate was the only form which you could get on your skin without issues.

I can still get lead in Shanghai and I can make lead glasses there but exporting them is an issue as well. I can't ship the monosilicate to myself without getting an EPA permit and I don't want to jump through that hoop. So, I'll either go make my lead stuff in Shanghai or watch the sun go down on the limited supplies I still have.

Chrome is very refractory stuff and the green aventurine is the easy one to make. I remain firm that Copper aventurine is the only other true aventurine out there.

[Art Freas]

Pete
Question are there any other theoretical aventurines out there looking at the periodic table?

[Pete VanderLaan]

I think based on their positions on the table that silver and gold would be feasible but never were pursued because of the costs of the metals. It takes a lot to make it work and it isn't really reliable.

If someone says it's a gold aventurine, it isn't. Think Copper and chrome and not nearly so much copper. Copper is hard.

Positioning yourself with stuff that no one else can do is really a skills based enterprise and it takes years.

[Michael Ahlefeldt-Laurvig]

Kugler has a wide range of lead free colors also- see menu on the left

http://www.kuglercolors.de/english/default_e.htm

[Rich Samuel]

Speaking of green aventurine, this is from last night's "Antiques Roadshow."

(Bonus: Can you spot the appraiser's boo-boo, kids? )

http://www.pbs.org/wgbh/roadshow/archive/201401A31.html

[Greg Vriethoff]

Originally Posted by Rich Samuel

Speaking of green aventurine, this is from last night's "Antiques Roadshow."

(Bonus: Can you spot the appraiser's boo-boo, kids? )

http://www.pbs.org/wgbh/roadshow/archive/201401A31.html

I sat through a bunch of bs about how the 1% is making things better for everybody and didn't see anything relevant to the glass piece in question.

[Rich Samuel]

Originally Posted by Greg Vriethoff

I sat through a bunch of bs about how the 1% is making things better for everybody and didn't see anything relevant to the glass piece in question.

Huh?

[Greg Vriethoff]

Originally Posted by Rich Samuel

Huh?

I'm not sure why, but all I got was a commercial when I tried playing the video.