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  #76  
Old 06-01-2018, 01:37 PM
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you can make your own silver chloride using the directions in Glassnotes 3. Henry hated the way I made silver Nitrate and thought I was a menace to society. I haven't changed. It looks like a mad science experiment when I do it but I hate waiting around. You can also make iodide and bromide from glassnotes as well. With iodide, you can draw on the glass. The sodium bromide and sodium Iodide are what will cost you since they come as a reagent grade. I think Noah handles both.

I always had trouble with Simpson trying to do too many things all at once. He consistently would add all sorts of shit to the Corona formula and frequently made it quite incompatible and rick expected me to fix it. . It was tiring.
No it won't flow between gathers.
Using too much is not a good thing for a variety of reasons.
Learn your basics well first. The silver has not brought you to your knees yet, but it will.
Good Design is way harder than any of this stuff.
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  #77  
Old 06-04-2018, 10:07 AM
Dan Vanantwerp Dan Vanantwerp is online now
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Round 2b?

Went back to a 91 LEC version of Brossphate to make sure I tested it properly. All the tests at 88.6 suggested that I was too low. BUT, the 91 did not fit any better (seemed worse). One last try...gonna take it all the way down to 87.

If that works I'm gonna put a big ol' asterisk next to phosphate opals and fitting other glasses. Weird...
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  #78  
Old 06-04-2018, 10:30 AM
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I run back to your post #15.In that post you refer to the standard E&T calcs and at the same time try to attach actual measured calculations and then refer to 96 color rod measurements. It's comparing apples and oranges.

Reasonably speaking a lot can be learned here from a simple pull test. If you have a bench torch for lamp work, take a cane of each glass about the diameter of a pencil and heat them in that torch. when they're both hot enough to stick to each other, overlap each rod on the other about an inch. Heat them and slowly work them until the have really melted together. Then pull out of the flame and holding each rod with equal pressure, quickly pull them away from each other and hold them in tension until they're cool. PULL STRAIGHT. This may require some practice. Cut the pulled cane in the torch from either rod, the clear or the opal. If over 12 inches of run, there is a gap of 1/2 inch or more measured against a straight surface , it's clearly incompatible BUT the important thing about this test is you can sight down the thread and see which one is on the inside. The one on the inside has a higher expansion.

I don't like this test but you need something here to get you to stop going all over creation with your quest. This test really does work with glasses of similar structure and it can be quite deceptive with dissimilar glasses BUT, it will show you a path as to which one needs work. If you're fortunate, it will get you to where you can do a ring test and that really helps define the adjustment.

Actually matching the phosphate to cristalica should not be all that hard but I think you're making it hard. Stop trying to use E&T if you're going to also compare them to measured expansions as well.
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Old 06-04-2018, 03:06 PM
Eben Horton Eben Horton is offline
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From an innocent bystander prospective, why not keep adding soda ash to bring the #’s up to the sweet spot? For example keep doing small melts and add say 5% more soda ash until you hit it. Silica if you need to lower the #. Am I missing something here ?
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  #80  
Old 06-04-2018, 04:05 PM
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What you're missing is he doesn't know which way to go. The pull will tell you .

What I'm less than clear about is what size batches are being mixed here. What quality scale is being used? The smaller the batch the greater likelihood for error. Same with the scale. How's it actually getting mixed.
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  #81  
Old 06-04-2018, 06:10 PM
Eben Horton Eben Horton is offline
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He needs a dilatometer
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  #82  
Old 06-04-2018, 10:12 PM
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Why make such a big jump? If one seems low and the other high...
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  #83  
Old 06-05-2018, 01:26 PM
Dan Vanantwerp Dan Vanantwerp is online now
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I'd love a dilatometer...got $2000?

I'm gonna follow my nose on this one. As I lower the LEC, things seem to get better. I was satisfied with the thread tests I ran, but they told me nothing. I think Jordan found the answer with his 87.5 LEC match to Cristalica with the 5% Brossphate. We'll see.
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  #84  
Old 06-05-2018, 03:17 PM
Eben Horton Eben Horton is offline
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You can build your own with a gauge from McMaster Carr that measures ten thousandths of an inch and a quartz tube. Presto! Done.
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  #85  
Old 06-05-2018, 05:51 PM
Dan Vanantwerp Dan Vanantwerp is online now
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I'll look through the Archives for that DIY project. I'm currently walking through them year by year (Yes, my job asks me to sit in front of a computer for hours). There was a lot on that around 2003. Some of you guys have been posting for a long time. I think you have always been one of the more helpful contributors, Eben. For what it's worth, thank you!
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  #86  
Old 06-05-2018, 06:07 PM
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building one is an issue and you have to see it. It's another tool. Sometimes good, sometimes not so good. It takes a village.
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  #87  
Old 06-05-2018, 06:41 PM
Dan Vanantwerp Dan Vanantwerp is online now
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So, by walking through the Archives I came across Dave's nice description of getting to his first, best phosphate opal...he had not come across the strontium idea yet. This is how he described the compatibility tests:

"
Now another interesting thing...

I'm working on matching the expansion to 96 and have been using thread pull tests and polariscope. I know that the phosphate and my clear are really different glasses and that a straight thread will not equal a perfect match, but does anyone remember if the phosphate has to test higher or lower to match? I've come 2 points (E&T calculations and equivalent change in the thread))down in expansion from where the final position of the thread shows the phosphate higher expansion, to where the thread is straight, to about one point (calculated) below where the thread was straight. They all show stress in the polariscope.

I also know there are very different overall expansion curves between the clear and the phosphate. When you first pull the thread test it looks like the phosphate is lower than the clear, then after it cools about 30 seconds or more the thread will bend back in the opposite direction quite a bit. That's a lot of change at the transformation point and I know it's the phosphate because this is the only time I've seen that. I've made a few things from each batch and the stuff within about a half point either way from where the thread is straight will withstand diamond sawing and a few other rudimentary stress tests.

I'll answer my own question. The ones that pull straight on the thread test can be de-stressed by coming through the tail end of the annealing process (around transformation point) more slowly."

I'm not sure how I would achieve this tail-end, annealled thread testing, but I really don't want to try anyway. I'm not sure this glass was ever really fit to a "96" clear. I think it's interesting that Dave noted such weird results when comparing theoretical expansion, thread and stress testing. No matter. The stuff is pretty awesome and would be worthy to me as a standalone glass. That I have fit it to Pete's silver opal is really awesome. I'll probably drop Cristalica anyway and focus on a batched clear. Down to my final 2 boxes of cullet.

Thanks for everyone's help in the village
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  #88  
Old 06-05-2018, 07:01 PM
Eben Horton Eben Horton is offline
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Quote:
Originally Posted by Pete VanderLaan View Post
building one is an issue and you have to see it. It's another tool. Sometimes good, sometimes not so good. It takes a village.
If I remember right, your one from the first color class was simply a 12 inch quartz tube with an ID of about 5/16tgs and a 1/4” quartz push rod that was about 1 inch shorter than the tube. You would pull a length of your glass that you wanted to measure making sure it was thinner than the I.d. Of the tube and cold work it to exactly 1 inch. Insert the piece in the tube then the push rod and secure the gauge and tare the gauge to zero. Slide it into a small oven and bring it up to 1000 degrees and take a reading on th gauge, which would give you a theoretical expansion reading of 10 thousandths of an inch.

I think that’s how I remember it all working.
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  #89  
Old 06-06-2018, 07:46 AM
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My clear and also my unoxidized batch glasses are a 96. Cristalica is a 97.0. My older unoxidized formula was as I recall in the mid 95's.

The memory of the dilatometer is reasonable short of the brass fitting into which the gauge slips into and gets screwed down. I would not say it was cheap to build nor would I say it's foolproof. It's a tool. It required a very tight kiln to measure in if you recall Eben and without it ( A tubing annealer) it would be a rough go to get tight numbers. It also requires a handheld temperature measuring device. If you recall, I had an omega unit to read the kiln. The test sample in fact was 4mm x 4.000. In all of these tests, they point in a direction. None are foolproof. The goal is to have all the indicators pointing in the same direction. They are the Hagy Seal, the ring test , the pull test and the dilatometer. Doing all of the tests requires experience. If you send material to Corning for testing, They will tell you to always ask for the same technician you have been using. There's a reason for that.

Using Dave's early stuff before the strontium as I recall did use calcium and had the subsequent apatite crystals. Cristalica is an outlier as an expansion. I encouraged Kuchinke to lower that expansion a half point but those guys really never wanted to hear from me about changes in the goop. Switching to mostly strontium did improve things vastly. I think using such things as 20 mule team borax may be a mistake, it does seem to have other things in it. I am going to have Jim mix the stuff for whoever wants it in the west and it will be decidedly different than Cristalica. Melting in a wire melter is not something I've tried.
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  #90  
Old 06-06-2018, 10:39 AM
Dave Bross Dave Bross is offline
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A dilatometer does not tell you anything about the variations between two glasses on softening point, which is the point where the glass hardens up from a liquid to a solid.

If one sets up before the other is done shrinking you have a mismatch.

If softening points mismatch, then two glasses testing the same on dilatometer expansion will not fit.


To answer the question about weirdness of thread tests on phosphates. I tried to simulate how many strikes the particular work I was going to do would require. I did these strikes at the stage where the two glasses were melted together (pre-pulling) for the thread test. I shot for having a straight thread on final cooling after doing this and pulling the thread.


Further thoughts...the E&T numbers are most useful after you have a thread test showing how far off you are. In my little world in my style of thread test 1 mm of bend over 200 mm is equivalent to .6 in E&T numbers. If my melt was off 1 mm on thread test I would then go to my E&T calculator and change the ingredients to change the final E&T number .6 for mixing the batch for the next melt or to get amounts for any attempts to add things to correct the melt sitting there.

Using E&T numbers prior to having compatibility proof is just a shot in the dark. If you know what E&T number your furnace needs (each furnace is unique on this) for your clear it increases your odds of coming up close by shooting for that number. Those E&T numbers will get you closer than anything else on the first try but rarely will they hit it.

More fun with phosphate - our side trip into decolorizers reminded me of this - try a tiny bit of phosphorous (less than .5 %) in your clear batch. Brightens it up noticeably. Thanks to Scholes for that one.

I never tried it, but wondered if a tiny bit of phosphorus in the chalcedony wouldn't do something interesting. What it might do is screw it up due to all the oxygen in the phosphorus but maybe not in a tiny amount as in brightening the clear. The "glass within a glass" nature of the phosphate might do something fun.

One more - the yellowing Cristallica actually looks like iron green on my monitor. Could it be iron contamination?
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  #91  
Old 06-06-2018, 10:47 AM
Dan Vanantwerp Dan Vanantwerp is online now
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I've been a little concerned about the 20 mule borax but really hesitate to change. I checked the MSDS on the stuff and found this a little uncomfortable:

SECTION 3: COMPOSITION / INFORMATION ON INGREDIENTS

INGREDIENT CAS NUMBER PERCENT (w/w)
Sodium Tetraborate Decahydrate 1303-96-4 60 – 100 %

Now, the 40% difference could just be variable water content in a more or less humid area, but they never go into it. I'm adding about 300g into 10 lbs so any contamination is not insignificant.

I'll get some 5M and give it a shot if this next round is a total head scratcher.
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  #92  
Old 06-06-2018, 02:03 PM
Dan Vanantwerp Dan Vanantwerp is online now
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Hi Dave, Always glad when you have a chance to chime in.

I made sure my sample was struck prior to pulling threads, but it would be tough to try and get it matched to the level of strike for a piece completely worked and boxed.

Have you read the opal phos technical posting put out by Gaffer on their website? They suggest that the bubbles of PO4 continue to grow as the piece is worked making compatibility a bit of a moving target.

In the archives, on a different discussion about compatibility, there was mention of someone working on a piece for 5 hours. Imagine the change in expansion for an opal phos by the time it was boxed if it even made it! Someone else said that opal phos reacts violently with water which I hope you would agree is not true. Pete was a bit skeptical and asked what the chemistry behind that was. I can't imagine what was happening. That you were pre-wetting your batch suggests you took it with a grain of salt.

It's like a course in recent (and sometimes not-so-recent) glass history in that section. There is mention of a cad-sel red opal phos. Did that ever get made?

You're probably right about the iron in the Cristalica, but I plead ignorance of the source. That crucible (80lb) has been kept isolated from anything but cullet. Nice to have a redox indicator built into the glass.

I am on the same wavelength as you with merging Brossphate with Chalcedony. I think Pete has mentioned a phosphate based chalcedony as well. I'm taking my steps to get there and learning along the way. One great thing I take with me as a recipient of an advanced degree...I know how to learn, how to be taught and how to teach myself.
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  #93  
Old 06-06-2018, 02:05 PM
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I would not view that as insignificant.
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Old 06-06-2018, 02:11 PM
Dan Vanantwerp Dan Vanantwerp is online now
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That's what I meant. 300g is darn near a lb (453g) so just under 10% of the total weight IS significant.
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Old 06-06-2018, 03:53 PM
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How big a batch do you actually mix and melt at a time?
Phosphates shouldn't be confused with typical opals. Opals grow crystals. They grow and collapse and grow again. They rely on Alumina or calcium Fluoride to grow them. Phosphates still need some calcium to work but not to the point of making a bunch of apatite snot. Phosphates have two glasses in solution at the same time which go through an actually separation going from cooled to heated. It's a billion tiny bubbles causing the opalescence, not crystals.

I would have to think for some time about Dave's assertion about mismatch in the cooling process. I don't think I agree with it at all. Your goal is to have two glasses showing no mismatch at room temp after annealing. The pull test is usually a confirmation that neither glass is tugging on each other at that time. That's true of the Ring and the Hagy as well. I can see wanting to attempt the strike on the opal when drawn as a clear as well as after the phase separation occurs. I would find that info useful.
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  #96  
Old 06-06-2018, 05:01 PM
Dan Vanantwerp Dan Vanantwerp is online now
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10 lbs. My color crucibles are 17 lbs. I am able to get 6-8 lbs charged before my first blow session Saturday and then top off with the rest for Sunday.
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  #97  
Old 06-06-2018, 05:28 PM
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I don't do color tests under 20 lb mixes because I feel the potential for error at the scales gets too big. That number you just gave for the 20 mule team borax just grew to be a monster.

What is you scale that you use for everything??
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Old 06-07-2018, 10:19 AM
Dan Vanantwerp Dan Vanantwerp is online now
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Recall that the majority of my mixing has already been done by Jim. I am just adding borax, phosphate and sand. My scales are all digital. I'm on the lookout for something analog, but these are working well. I have tested them with controls.

Just added some 5M borax to an existing order at the pottery supply store. Should have just waited to get some but I got impatient and Lowes had the 20 mule.
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Old 06-07-2018, 06:31 PM
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One other thought.....the lower percentage of phosphorus as in the original recipe will probably give you less trouble on expansion matching. That smaller amount gets pretty dense if struck a few times.
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Old 06-07-2018, 10:55 PM
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Hi Dave, I'm hoping this thread helps anyone else that might want to get into the Brossphate craze so I'm glad you brought the density up. I think the 2.5% is ok but at 3.2% I can really get a solid white. I was getting a fairly patchy effect down lower. In practical terms, multiple reheats just to strike the color really ups the time to make a piece of glass and time is $$.

I would say that my melting technique has gotten better so now I might get a better white at a lower %. Man, the 3.2% is nice though...starts clear and over a couple heats fades to that solid, wet white I think it would also still be possible to get the veiled effect you and others have discussed with less strikes or perhaps a thin strip gather.

Just charged with my latest mix so we'll see if I guessed right and can get a match to Cristalica. I have a match to Pete's older chalcedony recipe at 88.6 LEC. It was still pretty off from Cristalica so I dropped it to 86.5 LEC for this test.

A great example of A fitting B, B fitting C, but A not necessarily fitting C.
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