Draping / slumping Robax glass
Moderators: Brad Walker, Tony Smith
Draping / slumping Robax glass
HI Folks
I've been asked to look at 'bending' some Robax heat-resistant glass over a (probably stainless-steel') former.
This is the stuff
http://www.us.schott.com/hometech/engli ... cts/robax/
Anybody know anything about this material ?
- it's claimed to be "an extremely heat-resistant, transparent ceramic fireplace glass"
- I'm going to fire some in the kiln and see what happens, but I'm wondering if anybody else has been here before ?
Thanks
Adrian
I've been asked to look at 'bending' some Robax heat-resistant glass over a (probably stainless-steel') former.
This is the stuff
http://www.us.schott.com/hometech/engli ... cts/robax/
Anybody know anything about this material ?
- it's claimed to be "an extremely heat-resistant, transparent ceramic fireplace glass"
- I'm going to fire some in the kiln and see what happens, but I'm wondering if anybody else has been here before ?
Thanks
Adrian
-
- Posts: 57
- Joined: Sun Dec 13, 2009 9:35 pm
Re: Draping / slumping Robax glass
Have you written the company to see if they will provide information about firing?
Re: Draping / slumping Robax glass
HI Alexis
Thanks for your reply.
Yes - I did contact them - but they've not replied yet.
I've been running some test - and managed to get the beginnings of a slump
(perhaps a few millimetres across an 8-inch length)
firing at 880c for 15 minutes - don;t really want to go much hotter than that
with my new kiln - so shall try another firing taking it slower, and maybe with 60 minutes at the process temperature...
Thanks
Adrian
Thanks for your reply.
Yes - I did contact them - but they've not replied yet.
I've been running some test - and managed to get the beginnings of a slump
(perhaps a few millimetres across an 8-inch length)
firing at 880c for 15 minutes - don;t really want to go much hotter than that
with my new kiln - so shall try another firing taking it slower, and maybe with 60 minutes at the process temperature...
Thanks
Adrian
-
- Posts: 1037
- Joined: Sun Mar 09, 2003 5:59 pm
- Location: Massachusetts, USA
- Contact:
Re: Draping / slumping Robax glass
A possible outcome is that the glass wll no longer be heat-resistant. If you are depending on its heat-resistant properties, reheating and annealing without a proper (and perhaps proprietary) schedule may make the glass behave like "normal" glass.
Tony
Tony
The tightrope between being strange and being creative is too narrow to walk without occasionally landing on both sides..." Scott Berkun
-
- Posts: 2339
- Joined: Tue Mar 11, 2003 12:06 am
- Location: Chatham NH
- Contact:
Re: Draping / slumping Robax glass
Tony, what makes you say that? Isn't this glass simply low expansion borosilicate glass? If so, it is what it is. Low expansion glasses are easier to anneal. That said, I have no clue what temperature one would anneal at. I suspect it is quite high, as anneal soak is about 100ºF below the temperature when it will first begin to slump.Tony Smith wrote:A possible outcome is that the glass wll no longer be heat-resistant. If you are depending on its heat-resistant properties, reheating and annealing without a proper (and perhaps proprietary) schedule may make the glass behave like "normal" glass.
Tony
In the olden days, pyrex was low expansion borosilicate glass. These days they use soda lime glass and heat strengthen it (tempering). With this glass, you would surely lose the strengthened qualities once it is heated above the strain point.
Bert
Bert Weiss Art Glass*
http://www.customartglass.com
Furniture Lighting Sculpture Tableware
Architectural Commissions
Bert Weiss Art Glass*
http://www.customartglass.com
Furniture Lighting Sculpture Tableware
Architectural Commissions
-
- Posts: 1037
- Joined: Sun Mar 09, 2003 5:59 pm
- Location: Massachusetts, USA
- Contact:
Re: Draping / slumping Robax glass
Sorry Bert. I've never heard of Robax before. There are lots of glasses that are made "heat resistant" by tempering or other modified annealing schedules as you know. There are also glass-ceramic matrices (Schott Zerodur comes to mind) that depend on specific annealing schedules to maintain their low thermal expansion which render them thermally resistant. If Robax is just a brand name of boro, then in agree that it should have the same heat-resistant properties after slumping as it did before.
Tony
Tony
The tightrope between being strange and being creative is too narrow to walk without occasionally landing on both sides..." Scott Berkun
-
- Posts: 1037
- Joined: Sun Mar 09, 2003 5:59 pm
- Location: Massachusetts, USA
- Contact:
Re: Draping / slumping Robax glass
Indeed, Robax is a glass ceramic matrix, and not a borosilicate.
http://www.schottrobax.com/?WTS=1&WTC=H ... -Warm-Safe
Proceed with caution.
Tony
http://www.schottrobax.com/?WTS=1&WTC=H ... -Warm-Safe
Proceed with caution.
Tony
The tightrope between being strange and being creative is too narrow to walk without occasionally landing on both sides..." Scott Berkun
-
- Posts: 773
- Joined: Mon Mar 10, 2003 11:36 am
- Location: Tofino, British Columbia, Canada
Re: Draping / slumping Robax glass
Broken stove top so called glass that I tried didn't do anything with 'normal' fusing and firing temperatures and schedules.
-
- Posts: 2339
- Joined: Tue Mar 11, 2003 12:06 am
- Location: Chatham NH
- Contact:
Re: Draping / slumping Robax glass
I replaced a piece of glass in my pellet stove after it broke during shipment. Spendy little sheet of glass. I never gave any thought to bending this stuff. It is a whole different ballgame I guess...Tony Smith wrote:Indeed, Robax is a glass ceramic matrix, and not a borosilicate.
http://www.schottrobax.com/?WTS=1&WTC=H ... -Warm-Safe
Proceed with caution.
Tony
Bert
Bert Weiss Art Glass*
http://www.customartglass.com
Furniture Lighting Sculpture Tableware
Architectural Commissions
Bert Weiss Art Glass*
http://www.customartglass.com
Furniture Lighting Sculpture Tableware
Architectural Commissions
Re: Draping / slumping Robax glass
HI Folks
Thanks for all the comments...
I've failed to get the stuff to bend, despite having taken it up to 880c (in my homebuilt kiln, waterglass slumps at 680c and float slumps at 780).
I didn't want to go any higher, for fear of upsetting my new kiln...
Schott (the manufacturers of the Robax glass) replied to my email as follows
"Unfortunately I have to tell you that the glass ceramic material which you can buy on the market, you can't bent any more. Only we as a producer of glass ceramic can do this processing step before turning this specific material into glass ceramic. "
So it sounds as if their manufacturing process is 'form to shape' then 'process' -
so, without knowing what the process is, you run the risk of ending up with a formed piece of glass that's no longer heat-resistant!
This is probably why Schott charge a significant premium for supplying formed glass for use in 'bow-fronted' stoves..
Thanks all
Adrian
Thanks for all the comments...
I've failed to get the stuff to bend, despite having taken it up to 880c (in my homebuilt kiln, waterglass slumps at 680c and float slumps at 780).
I didn't want to go any higher, for fear of upsetting my new kiln...
Schott (the manufacturers of the Robax glass) replied to my email as follows
"Unfortunately I have to tell you that the glass ceramic material which you can buy on the market, you can't bent any more. Only we as a producer of glass ceramic can do this processing step before turning this specific material into glass ceramic. "
So it sounds as if their manufacturing process is 'form to shape' then 'process' -
so, without knowing what the process is, you run the risk of ending up with a formed piece of glass that's no longer heat-resistant!
This is probably why Schott charge a significant premium for supplying formed glass for use in 'bow-fronted' stoves..
Thanks all
Adrian