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  #101  
Old 06-09-2018, 08:01 PM
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Quote:
Originally Posted by Dan Vanantwerp View Post
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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If you are using 10 lb mixes, if I understand that correctly, and you are adding around 300 grams of material to a mix you say Jim at East bay has already mixed, and you suggest it is mostly mixed by east bay, I think you're wrong. What I do think is that you're adding about 8% new materials to Jim's stuff in various semi hostile forms. In my mind, that''s a very large number. so, again, how are you mixing this new stuff in? What is your mixer?

Process is key in doing this stuff.
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  #102  
Old 06-11-2018, 12:39 AM
Dan Vanantwerp Dan Vanantwerp is offline
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Success!

New recipe based on a 86.5 LEC worked perfectly for both the Cristalica AND Chalcedony glasses. Seems this stuff really wants a relatively low theoretical expansion to match a "96" glass just as Jordan suggested.

I performed the ring test with inside and outside applications. I was surprised enough when I opened the annealer to find everything intact. To pass the ring test with flying colors was hoped for, but really unexpected.

Going to repeat the formula in a larger scale and see if it passes a second analysis. Strangely, this mix seemed to strike a bit more quickly/easily than the previous mixes so I'll see if that remains consistent.

Pete, I'm doing my best to mix in a little food bucket I got at the restaurant supply store. They actually make a strainer that fits right on the top of it. I bought the lid and do some hard shaking, rolling and turning. I have thought of trying to secure it closed and place it in my cement mixer for a while. I've also used the drill mixer method but I don't think it's as thorough as what I've described.
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  #103  
Old 06-11-2018, 07:12 AM
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I am glad you are getting a fit. With the mixing you describe, I kind of doubt your results will be consistent. When I do a color additive using my clear that Spruce Pine mixed for me, in 14 lbs, adding seven grams, it goes back in the cement mixer for a half hour.
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  #104  
Old 06-12-2018, 03:50 PM
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Get yourself a drill driven paint mixer, preferably plastic but steel works fine. The steel ones eventually eat up the bucket.

This will mix it up REALLY well and make you feel less like a performing monkey rolling a bucket around.

You can fabricate a dust cover for the bucket from plastic, cardboard, or whatever. The commercial ones look like a shower cap for someone with a head the size of a bucket and a hole dead center for the mixer shaft.

I just take it outside and wear a respirator and gloves.


https://www.homedepot.com/s/paint%2520mixer?NCNI-5
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Last edited by Dave Bross; 06-12-2018 at 03:53 PM.
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  #105  
Old 06-20-2018, 02:31 PM
Dan Vanantwerp Dan Vanantwerp is offline
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Confirmation

The results repeated with a new batch of Brossphate. Under my conditions, a theoretical expansion of 86.5 is the target. I've started making pieces with layers of Cristalica, Brossphate opal and Chalcedony with nice results. I'm about ready to try some colors, in addition to the white.

Just as Dave described, the glass can be made more opaque with additional reheats. It is worth taking an oxypropane torch to this glass to watch the waves of opacity form. I believe this is how Dave uses the glass and I didn't quite grasp what he was describing until I looked at it this way. With a torch and air gun (heat-cool cycles) the deep opacity can be coaxed out very easily. I was even able to get just a small section of the piece (the lip) to go deep opaque. Poor man's lip wrap
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  #106  
Old 06-30-2018, 10:50 AM
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Good, glad you've got it working for you.

Lots of possibilities there with the striking characteristics.
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  #107  
Old 07-02-2018, 08:12 PM
Dan Vanantwerp Dan Vanantwerp is offline
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Brossphate Blues

Guess I'll continue my journal on the Brossphate Adventure:

I tried a periwinkle (3 grams cobalt oxide+30 grams red copper oxide/10 lbs batch). OK color (the cobalt sort of took over), but it fell out of favor with the Cristalica. Pete has discussed how copper can cause dramatic changes to viscosity which I certainly noticed. I thought at this small quantity I might get lucky on compatibility. My test cylinders made it out of the annealer but not off the saw. I wasn't crazy about the color so I'll just try the copper alone at 30 grams per 10 lbs and see if I can find a match.

I'm also curious to play with reduction in this glass and will see if I can push around the blue-green to red transition with black tin.
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  #108  
Old 07-02-2018, 08:38 PM
Jordan Kube Jordan Kube is offline
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I think I remember reading these glasses don't work as well in reduction but I could be wrong. I think copper by itself in glass is one of the most beautiful colors.
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  #109  
Old 07-03-2018, 07:07 AM
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that should not be enough copper to throw that off. You are doing something else to make that happen.
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  #110  
Old 07-08-2018, 10:09 PM
Dave Bross Dave Bross is offline
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Look at how much oxygen is in any form of phosphorus that would work in a glass melt.

I don't think reduction colors are going to happen.

Copper ruby overlaid on white phosphate is gorgeous though.
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  #111  
Old 07-09-2018, 01:54 PM
Dan Vanantwerp Dan Vanantwerp is offline
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I tried again with uncolored as opposed to the copper-cobalt and had the exact same results. I started a new box of 20 mule borax and suspect that something changed..maybe the sodium content from lot to lot is variable. Next on my "to do" is making up my own batch and using 5M borax instead. I'm guessing that the matching LEC will actually be quite different and I've been carrying over some unintended ingredients. Have to call it for a little while as I prep for my big show. I'll start 2 color pots with chalcedony variations using cullet.

Reduction does sound iffy but if anything can do it black tin can.
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  #112  
Old 07-09-2018, 02:35 PM
Jordan Kube Jordan Kube is offline
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Large amounts of tin will stiffen the glass up and you will definitely be adjusting for expansion.
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  #113  
Old 07-09-2018, 04:05 PM
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I'm looking at converting an old element furnace I have into a multi-color pot test furnace. I want to try some of these things on a smaller scale before going into my 17 lb pots. The C5.5 here looks good.
http://www.sundanceglass.com/cruciblesr.php

I actually bought one when determining what I would use in my current setup but went with two C7.1s instead. These little guys are well made and really last (and cheap!).

It would require a lot of testing no doubt. I'm more interested in trying out many different colors in opal phosphate. BUT...a nice cobalt luster would be pretty sweet. Good winter project.
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  #114  
Old 07-09-2018, 08:20 PM
Dave Bross Dave Bross is offline
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Second what Jordan said.

Tin also speeds up the set time radically which makes it anywhere from a bitch to work to impossible as it sets before you make it to the marver.

Changing set point/time changes compatibility so this throws off the matching characteristics too and you're back to figuring out what it would take to match it.

If you're going to try it use phosphoric acid for the phosphorous and be damn careful with it. It carries the least oxygen of any source I could find so less black tin would be needed.

I haven't tried this, just thought about it, and there would probably be a VERY violent reaction mixing an acid with all that alkalai in prepared batch so perhaps soaking it into the sand first and drying it out like you would a gold ruby would be the way to go.

You can buy phosphoric acid on Ebay in 80-some percent solution.

The crucibles you linked to are assay crucibles. You can buy them much less expensively. Hit the search engine here for the actual sources and what you need to know about shipping them.

Lose the Borax and add more nitrate if you want it to melt faster and be less trouble. Recalculation will be necessary of course.
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Last edited by Dave Bross; 07-09-2018 at 08:27 PM.
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  #115  
Old 07-10-2018, 09:19 AM
Jordan Kube Jordan Kube is offline
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I think phosphoric acid would be an invitation to cement land in addition to the things Dave mentioned.
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  #116  
Old 07-10-2018, 11:01 AM
Dan Vanantwerp Dan Vanantwerp is offline
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I think that a reduced phosphate opal would be good if it could be done with some modification of the existing formula...maybe low PO4 % with moderate black tin. At least start there and see if it's feasible. Getting too far away from that would suggest to me that it doesn't want to be done.

It's impressive that black tin can overcome a cullet oxidation. At my elevation I only use 5g black tin in cullet...30g is way too much. I may actually have a better shot then those at sea level to get this to happen.

Question then becomes...when have you "hit" a reduced glass?
I might try to run silver bromide over the surface, use tramp iron as a color changer or copper (blue versus red). Iron would be a nice addition if the goal was a opal-phos chalcedony.
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  #117  
Old 07-10-2018, 01:54 PM
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As Dave pointed out reducing a glass chock full of oxygen is not going to go well. Better to case the reduced color with a phosphate opal. Having them fit each other is always a good plan.
Black tin isn't overcoming cullet oxidation. Much of the oxygen is driven out of the initial melt in the first place. A second melt, fritted will have less O2 still. Easier still to just make the low O2 glass in the first place. Use things like potassium hydroxide instead of the carbonate. Shave it where you can.
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  #118  
Old 07-10-2018, 04:06 PM
Dan Vanantwerp Dan Vanantwerp is offline
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Might it help to liberate some of the oxygen by fritting the opal phos glass first and starting with a once melted glass?
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  #119  
Old 07-10-2018, 08:06 PM
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I very much doubt it. Phosphate glasses work because of a phase separation between a silica and a phosphate based network forming glass. I tend to think that each remelt would result in a homogenization of the batch, cutting down the strike a lot.

I haven't tried it though but there's lots of stuff i would not be incined to try. I'd make a fluorine first.
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