CraftWEB Hot Glass Talk  

Go Back   CraftWEB Hot Glass Talk > Color work from rods and batch glasses

Reply
 
Thread Tools Display Modes
  #1  
Old 12-17-2021, 07:29 AM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 23,477
Pete VanderLaan is on a distinguished road
fluorine affecting expansion

So, I took on a job making an opal white to match a non regular clear and have run into something which I've now heard of three times in almost fifty years of melting.

About ten years ago, John Croucher had written to me regarding the use of the Strainoptics polarimeter. As a side bar to that conversation he wandered into whites and fluorine. He was making a leaded fluorine and was trying to bring the expansion up and commented on that. He said that they kept on adding potassium to the glass and nothing happened. He indicated that they finally got there but could not beleive how much they had to add to move it.

I'm having the same experience and will come back to it but I called up Mark Peiser to see if he had ever run into this happening. He had. About forty years ago he was making opal whites and couldn't get them to budge. Currently he is looking back through his own records to see if he can find it.

Mine was taking my white which fits a 96 just fine and moving it up the ladder adding fluxes . These glasses are inevitably low on silica by conventional standards. In enamels, it's common to find that to be below 50%. What one wants to avoid is having it turn chalky. Right now, I'm below 60% but seem to be getting nowhere. I will do one last melt using sodium as the tool but after this, if it is non responsive, will turn to potassium, see what it does and then potentially replacing silica with titanium ounce for ounce. Adding lead is not an option.

This isn't a thread to declare victory over the problem. I am simply putting it out there for people interested in batched fluorine glasses as difficult. Ten years back, John sent me a bunch of Lauscha formulas reputed to be above 100L.E.C. I will try a melt with a simple white from that set of papers. I really miss John and our conversations. I've kept them all, we seem to keep everything except for those important to us.
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #2  
Old 12-17-2021, 08:13 AM
Josh Bernbaum Josh Bernbaum is offline
Registered User
 
Join Date: Feb 2009
Location: Brattleboro, VT
Posts: 854
Josh Bernbaum is on a distinguished road
I seem to recall you saying that fluorines, at least yours that we went over in the class, were in the 70's for LEC. Can't remember if that was calculated or measured, or both. But they fit a 96, and I suppose I'd been under the impression that was due to viscosity making up for the expansion in terms of fit. Am I remembering that correctly? The last fluorines I melted years ago were before I started using a spreadsheet more consistently like I have been more recently.
__________________
www.jmbglass.com
instagram.com/joshbernbaum_glass
Reply With Quote
  #3  
Old 12-17-2021, 10:44 AM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 23,477
Pete VanderLaan is on a distinguished road
The recorded number on the spreadsheet was a 72.0 if you wanted it to fit the 96. I have yet to pursue why that happens on the spreadsheet. I'm looking at the Lausha numbers right now and they are at 83.
If there's fluorine in the mix, I don't rely on the spreadsheets much at all. beyon my weird little 72 equals 96. I suspect it' only works for this formula.

The point I was trying to make was that if Fluorine is present in the glass, the effects of expansion from sodium and potassium seem to become negligible. That's consistent with what John and Mark both observed and neither had a clue why.
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #4  
Old 12-17-2021, 11:59 AM
Josh Bernbaum Josh Bernbaum is offline
Registered User
 
Join Date: Feb 2009
Location: Brattleboro, VT
Posts: 854
Josh Bernbaum is on a distinguished road
Adjusting sand and and cryolite ratios to raise expansion instead of sodium or potassium then?
__________________
www.jmbglass.com
instagram.com/joshbernbaum_glass
Reply With Quote
  #5  
Old 12-17-2021, 01:36 PM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 23,477
Pete VanderLaan is on a distinguished road
well, changing the cryolite changes three things, fluorine, alumina and sodium. Changing the silica is already perilous if it's under 60%.
It needs to be fairly dense, not so much as an enamel but the upper limit on fluorine is about 7%. Increase in sodium will make it go chalky. Increases in sodium is being brutal on the pots. I think I'm losing one now on the second melt. I melt at 2050F.
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #6  
Old 12-17-2021, 04:15 PM
Josh Bernbaum Josh Bernbaum is offline
Registered User
 
Join Date: Feb 2009
Location: Brattleboro, VT
Posts: 854
Josh Bernbaum is on a distinguished road
What do you mean when you say 'chalky'? I'm having trouble picturing that, and I'm guessing you don't just mean devit on the surface (which I got some of on the fluorines I did five years ago).
__________________
www.jmbglass.com
instagram.com/joshbernbaum_glass
Reply With Quote
  #7  
Old 12-18-2021, 06:51 AM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 23,477
Pete VanderLaan is on a distinguished road
It starts to look flat.
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #8  
Old 12-18-2021, 10:18 AM
Kenny Pieper Kenny Pieper is offline
Registered User
 
Join Date: Feb 2003
Location: Burnsville N.C.
Posts: 873
Kenny Pieper is on a distinguished road
Pete I am curious, what is your process for testing the expansion on these fluorine glasses
Reply With Quote
  #9  
Old 12-18-2021, 10:53 AM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 23,477
Pete VanderLaan is on a distinguished road
Right now, I make a ring test with the fluorine glass on the inside of the cup and the host clear outside. That is annealed and then a ring is cut from the cup on the diamond saw. If that survives the cut, it's pretty likely the two are compatible with each other BUT.. once the ring is cut, then a vertical score is made in the ring and tapped open. If the piece gaps trying to close, I know the inside glass has a higher expansion than the exterior one. The contrary is true if the gap opens up, then the interior glass is lower in expnsion. See the ring test illustrations in Glassnotes IV. I can fine tune with that info.

I also make a hagy seal with the glasses ( also see Glassnotes IV) but with the white, I'm simply not seeing any perceived strain when the ring test shows dramatic difference. That has me confused. The white is blinding.

Tomorrow, I'll set up the dilatometer which I've been avoiding since it is cumbersome to move it, but it simply measures what the glass does between 19-300C.
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #10  
Old 12-18-2021, 01:46 PM
Scott Benefield Scott Benefield is offline
Registered User
 
Join Date: Apr 2002
Location: Ballintoy, Northern Ireland
Posts: 95
Scott Benefield is on a distinguished road
For a down and dirty, and non-quantifiable, test you could do the Bullseye chip test and read it with a polariscope, since you have a known base clear that you want to test it against. I'm not sure why the Hagy seal won't read under the circumstances, which would be preferable. I think the chip test would tell you at least as much than the ring test, which is kind of ballpark.
Reply With Quote
  #11  
Old 12-18-2021, 03:00 PM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 23,477
Pete VanderLaan is on a distinguished road
I don't view the ring test as ballpark at all. Once you have a successful ring you can move right in on a perfect fit. Both the ring and the Hagy seal have the problem that if the mismatch is too great, the sample breaks. It doesn't take much of a mismatch to achieve that. It's where the dilatometer comes in handy. I don't know why the polarimeter won't show the mismatch with the white but it is irritating. Real opaque stuff is just hard to read. I have reversed the order of the cane layouts so I can put the clear on the inside and see the effect the white sandwich brings. I'll have those seals tomorrow.

Why do you think the bullseye test would do better?
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #12  
Old 12-19-2021, 01:13 AM
Scott Benefield Scott Benefield is offline
Registered User
 
Join Date: Apr 2002
Location: Ballintoy, Northern Ireland
Posts: 95
Scott Benefield is on a distinguished road
I suppose if the mismatch is that great, even the chip test would break. But I wonder if you could use that test in the same way, by showing degrees of retardation in comparative samples. I don't know your methodology, but I assume that by now you're going in one direction with this--trying to get the white up in expansion, for instance, instead of down. Wouldn't different chip tests show a relative difference read under the polarimeter? Dilatometry would be better.
Reply With Quote
  #13  
Old 12-19-2021, 07:32 AM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 23,477
Pete VanderLaan is on a distinguished road
I had to resort to bracketing and the samples from last night will show some things I hope.
It seems to me that to make what you're referring to would simply involve a gather of clear, flattened out and dipped on the side with the white, flattened out and then annealed. I imagine that would show stress but no indicator of the direction.

The dilatometer is a touchy tool is all I can say about it. What you want are all the indicators pointing in the same direction but once a ring test cuts with no gap or over bite- just sits there, I know I have it. I have hagy seals coming out this morning as well.
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #14  
Old 12-19-2021, 12:44 PM
Scott Benefield Scott Benefield is offline
Registered User
 
Join Date: Apr 2002
Location: Ballintoy, Northern Ireland
Posts: 95
Scott Benefield is on a distinguished road
I was thinking that if you did the chip test as you described, in different iterations of your changing formulations, you could measure the degree of stress by the same polarimeter that you use with Hagy seals. The thing about reading Hagy seals, though, is that the successful reading depends on very exact measurements of your rods--2mm, if I recall correctly. So you would have to standardize the clear substrate that you were using to test the white (and standardize that sample, too). But if you went to all that trouble, you could then compare one chip test to another, measuring the degree of retardation with your well-calibrated polarimeter, and get a quantifiable indication of your direction of travel (as it were). No? As I said, the dilatometer, although notoriously fussy, is really the instrument that was invented to solve this problem.
Reply With Quote
  #15  
Old 12-19-2021, 01:19 PM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 23,477
Pete VanderLaan is on a distinguished road
I've made, and not make Hagy seals that were thicker in my past and you could still easily see the strain when viewing a mismatch.
The saw is still such a great arbiter. If it doesn't fit, it cracks on the saw, always. If the hagy seal is off by a bit, the seal cracks.
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #16  
Old 12-20-2021, 01:04 PM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 23,477
Pete VanderLaan is on a distinguished road
I hit the sweet spot this morning and the rings saw smoothly and easily. It continues to be difficult to read the Hagy Seals. At this point they should not show strain.
So the next step is mixing it again and then retesting. Then I send some of the batch to the client and send a weight which I can accurately weigh here before shipping. It needs to weigh the same in both places. We've already established that we both have materials processed by the same vendors. Then, Jim mixes and sends some to me and some to the client. I melt yet again. We iron out process with the client. Their shop makes some nice white stuff cased in clear. From there on, they order what they need from me. It's a lot cheaper than using color rods and no one has to heat up color bar. You just gather.
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #17  
Old 12-21-2021, 08:36 PM
Marc Carmen Marc Carmen is offline
Registered User
 
Join Date: Jul 2015
Location: Rahway, New Jersey
Posts: 105
Marc Carmen is on a distinguished road
The method I use is something like the chip test Scott described. I fully fuse a small murrina of the color in question onto a few canes of the base glass. This is done quickly on a pastorelli in the hole. I put a small square of thin fiber paper on the kiln shelf first so the glass doesn’t stick because you have to get it pretty hot. Then it goes into the annealer. If there is any mismatch, you can’t really tell if the glass is higher or lower in expansion.

The trick is to make three base glasses, one that is -1coe with a bit of silica added, one master glass, and one that is +1coe with a bit of alkali added. Fuse a bit of color to all three glasses and under a polariscope you can easily tell which direction you need to go. I can also usually tell how far off the glass is too.

Typing this out I realize it sounds like a lot of work but you only need to make the -1coe and +1coe glasses once and you’re good. I made mine just melting a few lbs of the modified batch in a dollar store bowl in the glory hole. I also melt most color tests that way.

I’d try the ring test but this has worked so well for me. I know the cane test doesn’t tell you shit. Learned that one the hard way.
Reply With Quote
  #18  
Old 12-22-2021, 07:09 AM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 23,477
Pete VanderLaan is on a distinguished road
So, how do you access the glasses that are respectively 1.0 lower and higher than your master glass as you call it. 1. 0 is not enough to cause a mismatch break. With a chip it seems really hard to add either silica or soda to a tiny amount of batch and to then expect accurate results.
Pulled can only works with glasses of similar composition and then it depends on how you make up the cane. I love the ring test because it also tells you which direction to go in for fine tuning based on the gap or overbite..

In my own shop, I'm mistrustful of any mixed batch less than 20 lbs. I split that into three piles and start with one, evaluate, then 2, evaluate, then 3. Spruce Pine mixed my clear for me and that relieves me of having to deal with it for some time.
The dilatometer is quite handy in that it simply says what the glass is. It does not compare it to anything.
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #19  
Old 12-23-2021, 09:35 AM
Marc Carmen Marc Carmen is offline
Registered User
 
Join Date: Jul 2015
Location: Rahway, New Jersey
Posts: 105
Marc Carmen is on a distinguished road
Spruce pine batch is the standard. If we call that 96 coe, you can use it to make additional 95 coe and 97 coe glasses. My old notes say to add 4g silica per lb of batch to make it 95 coe. 2g soda ash per lb batch would make 97 coe. Double check those numbers. A ceramic bowl can usually hold 2 or 3 lbs of glass so I’d make 3 lb batches.

Pete, you don’t trust those digital gram scales that measure down to .01g? I have a $25 gram scale that has lasted years and is still spot on with the calibration weights.

Curiously, I’ve never had any fused samples break from mismatch, even when they’re pretty far off. They must be looked at under a polariscope where you’ll see a halo around any mismatched glass.
Reply With Quote
  #20  
Old 12-23-2021, 11:35 AM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 23,477
Pete VanderLaan is on a distinguished road
I weigh everything on two different scales for a reality check. Small ingredients on a triple beam balance.

I had SP mix my clear formula several years ago so I don't need to check it. I do my unoxidized stuff here. After this last experience with the hydrophylic alkalines, I now put them in Zip Loc bags as fast as they arrive. Losing 10% on desiccation was substantial.
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #21  
Old 12-31-2021, 06:28 PM
Jordan Kube Jordan Kube is offline
?
 
Join Date: Aug 2003
Location: Seattle, WA
Posts: 1,770
Jordan Kube is on a distinguished road
Here's a white recipe John gave Ed Skeels when I was working for him. I'll make a separate post with just the formula.

In grams:

Flint 7050

Soda ash 1725

Cryolite 1275

Zinc oxide 700

Potash 475

Whiting 400
__________________
WWUD? Think for yourself.
Reply With Quote
  #22  
Old 12-31-2021, 06:36 PM
Jordan Kube Jordan Kube is offline
?
 
Join Date: Aug 2003
Location: Seattle, WA
Posts: 1,770
Jordan Kube is on a distinguished road
Also, move it up and down with silica, not fluxes.
__________________
WWUD? Think for yourself.
Reply With Quote
  #23  
Old 01-01-2022, 06:54 AM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 23,477
Pete VanderLaan is on a distinguished road
Quote:
Originally Posted by Jordan Kube View Post
Also, move it up and down with silica, not fluxes.
Actually, that would be the normal and reliable way to do it Jordan but in all of the instances I have seen ( just 3 and they're rare), in each case we were moving it with either potash or soda since the amount required was huge.
I needed to move mine a full five points and the one John had written to me about was getting potash in an equivalent state. In all three instances the massive amounts added did not affect the expansion of any of those glasses. It did affect the viscosity. Seals and rings refused to budge. When it finally did easily survive the ring test, it was showing no movement at all in the Hagy seal. Ring tests are real world tests of surface tension.

Curiously, back when I did the color class, the only white formula that went off the rails was supplied by John. He told me that he did not understand but that his spreadsheet model had a terrible time doing fluorine whites. Mine simply converts the cumulative figure to another domain entirely. Maark apparently had the same problem. It's the only circumstance in which the light metals don't seem to behave as they normally do in the presence of the halide.
I really miss him.
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #24  
Old 01-01-2022, 09:48 AM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 23,477
Pete VanderLaan is on a distinguished road
Quote:
Originally Posted by Jordan Kube View Post
Here's a white recipe John gave Ed Skeels when I was working for him. I'll make a separate post with just the formula.

In grams:

Flint 7050

Soda ash 1725

Cryolite 1275

Zinc oxide 700

Potash 475

Whiting 400
****
I converted that to lbs and think it's a good deal higher than a 96 match but it is a well balanced on silica. I would suggest increasing the silica by .58lb and then would think it to be dead on. John's whites curiously never fit particularly well, even as rod.It seems perilously short of stabilizers.
__________________
Where are we going and why am I in this basket?
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 06:05 AM.


All published comments within these message boards are the opinions of its contributor and does not represent
the opinion(s) of the owner(s) of this website. Please see the Terms of Use file for more details.

Books to Help Artists Avoid Online Scams: Top 10 Email Scams | Social Media Scams

Powered by vBulletin® Version 3.7.2
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.
CraftWEB.com. Opportunity Network. 2008. All Rights Reserved.