CraftWEB Hot Glass Talk  

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

Reply
 
Thread Tools Display Modes
  #51  
Old 09-02-2017, 01:51 AM
Dan Vanantwerp Dan Vanantwerp is offline
Registered User
 
Join Date: Apr 2017
Location: Bozeman, MT
Posts: 103
Dan Vanantwerp is on a distinguished road
Hi George, The positive pressure idea sort of gets to Pete's mention of a reverse blower port to remove the fumes periodically. A continuous system as you describe would seem the better solution. Problem with air turnover is the loss of heat...we might lower the fluorine attack but still decrease the element life by making them work harder.

Although, hot air could be recuperated from a clean source...
__________________
My furnace setting: 2112
Reply With Quote
  #52  
Old 09-02-2017, 08:15 AM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 19,338
Pete VanderLaan is on a distinguished road
As I noted, Carlson did well with the hole in the furnace simply blowing the fumes out of the furnace through a dedicated hole. The difficulty would be that an electric unit needs to be really tight to retain heat, so there's the conflict.
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #53  
Old 09-02-2017, 10:48 AM
Randy Kaltenbach's Avatar
Randy Kaltenbach Randy Kaltenbach is offline
Registered DancingChicken
 
Join Date: Aug 2003
Location: Calgary, Canada
Posts: 940
Randy Kaltenbach is on a distinguished road
Still, if you use Richard's idea of a barrier of rammable or similar between the pot and the brick, the elements can be kept reasonably isolated from fumes. A vent in the lid can do the rest.
Reply With Quote
  #54  
Old 09-02-2017, 10:55 AM
Dan Vanantwerp Dan Vanantwerp is offline
Registered User
 
Join Date: Apr 2017
Location: Bozeman, MT
Posts: 103
Dan Vanantwerp is on a distinguished road
Coming back to one of the original seeds in this thread...how will Pete's unoxidized color base work with phosphate opals.

Are there things that could simply be added to achieve the melt characteristics that Dave has developed? Pete recommends a 2325F cook and it sounds like Dave has gotten this down a bit as he uses a wire melter.

I'm trying to get some opals cooking without starting a complete scratch, batch operation.
__________________
My furnace setting: 2112
Reply With Quote
  #55  
Old 09-02-2017, 11:42 AM
Mitcheal Veenstra Mitcheal Veenstra is offline
Registered User
 
Join Date: Apr 2002
Location: Arlington, Texas
Posts: 122
Mitcheal Veenstra is on a distinguished road
my next summer studio construction project will be building a small 2 pot gas color furnace for small scale color melting. Likely a variation of the little unit that Corning let us use in class.

I was amazed in some ways at how quickly/easily we made the colors we did in class. There are a lot of stumbling blocks along the path, and I'm sure there will be many times things don't come out the way I want them to. But the mystery and fear(?) of attempting my own color has been stripped away.

I've a set of tools to explore a new world. It's pretty darn nifty.
__________________
so much to learn.. so little time to learn it....
Reply With Quote
  #56  
Old 09-02-2017, 11:50 AM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 19,338
Pete VanderLaan is on a distinguished road
You're not quite getting it. The phosphate glass is an entirely different formula with similar viscosity and expansion characteristics. As a glass, it will fit both my clear formula and the clear base formula that has a good affinity for color as well.

I have melted Dave's phosphate and it's a very nice glass. It fit my basic portfolio the last time I tried it. Dave is spot on with one thing and that is to replace the calcium with Strontium. It makes what is difficult, easy. If you don't you'll see Apatite crystals everywhere. The only way to avoid hat in a calcum based phosphate is to melt at 2400F or hotter. Even so, I think it could have trouble being melted cold and I did melt it at about 2275F as I recall.

Now you will get an opal glass melting my color formula using silver but it will be a variation on many amber tones, never white. It strikes in many ways similarly to a phosphate which draws from the pot clear and then cooled substantially. Then on reheating the phase separation occurs more in the form of colloidal strands which are big molecules tending to reflect light rather than to allow light to be transmitted. They grow, they collapse, they grow again, always getting a bit fainter and that's pretty much true of any of the crystal/colloidal growth structures in glass.
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #57  
Old 09-05-2017, 08:00 PM
Dan Vanantwerp Dan Vanantwerp is offline
Registered User
 
Join Date: Apr 2017
Location: Bozeman, MT
Posts: 103
Dan Vanantwerp is on a distinguished road
I definitely wasn't getting it. I went back to the archives and Glass Notes to try and get a better handle on the various glass formulations and nomenclature.

Someone as unfamiliar as myself with color chemistry may not recognize that a phosphate "base" glass will be white (on striking). This was confusing me. Dave's glass is white, low-temp melting and low-devitrifying, a major accomplishment. The color threads on opal phosphates now make sense in that most of them would use a constant amount of sodium tripolyphosphate (STPP) in place of bone ash, and add colorants on top of the white. The Penland additive formulas would be used this way for the opal colors.

I'd like to get Pete's potassium clear glass batch for my normal clear, as well as my chalcedony colors, and Dave's phosphate batch to make other opal colors. This seems like the best way for me to open up a world of colors in my little two, 17 lb pot world. As I've mentioned, I don't have the facilities to store all these ingredients.

My intention now is to call East Bay and ask for a custom mix of Dave's most recent formula as follows:

"Here's what I've been melting in pounds:

Sand - 97.5
Soda Ash - 36
Hydrated Lime - 5.5
Strontium Carb. - 9
Zinc Oxide - 3
Borax 5 mol - 9
Alumina Hydrate - 4.5
Lithium Carb. - 1
Potassium Nitrate - 1
Sodium Tripolyphosphate - 6.5"

Want to be sure Dave is fine with this. I could add back the STPP separately as the Penland formula for Opal Red has a slightly lower bone ash contribution. I'm excited to get into this but know there will be many questions and don't want to step on any toes in the process.

Thanks!
__________________
My furnace setting: 2112
Reply With Quote
  #58  
Old 09-06-2017, 08:05 AM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 19,338
Pete VanderLaan is on a distinguished road
Jim may not have the STP and don't confuse it with TSP. Hydrated lime is not a generally popular form of calcium either. It may well be the case that you are not going to buy enough of the stuff to make it worthwhile for anyone to mix. Mine always came as a 1000 lb minimum. I did not recall that stuff having that much alumina in it and I'll go back and check.

In my shop, I have five base formulas that do different things but still play well together. I think John C has something like eleven now.
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #59  
Old 09-06-2017, 10:47 AM
Dan Vanantwerp Dan Vanantwerp is offline
Registered User
 
Join Date: Apr 2017
Location: Bozeman, MT
Posts: 103
Dan Vanantwerp is on a distinguished road
Waiting for Dave before anything. Then, I'll find out the minimum and perhaps some others have had an interest in achieving the colors Dave has described. Sounds like the STP is pretty easy to come by and may require some variable amounts based on the colors anyway.

My friend had a custom batch made up by East Bay and he sent Jim one of the ingredients. The results were not great and he figures it may not have been mixed (well) prior to bagging...similar to the SP color base.

That brings up an interesting question in batch production: is SP color base made up bag by bag? If a large amount like 1000lbs is produced and the final 50-100 lb bags are not mixed well...how does it ever get mixed? 1000 lbs of powders, flakes, crystals, etc layered into a hopper and bagged would never mix right if not mixed well prior to bagging. These must be layered in the bags and if they require mixing they were made individually.

In that case, it doesn't seem like the company should care that much if the order size is 2 bags or 50 bags. Just provide a sliding pricing scale based on volume and make it easy for small and large glass consumers to buy batch.
__________________
My furnace setting: 2112
Reply With Quote
  #60  
Old 09-06-2017, 06:38 PM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 19,338
Pete VanderLaan is on a distinguished road
My issue with SP on custom mixing has remained the same: Cleaning the mixer. At one point when I was doing color work for Josh Simpson's corona platters, he wanted SP to mix it and I said I doubted it would work. I had done the mixing at that time. It didn't work. There were some ruffled feathers and when questioned about cleaning the mixer, Tom said "You have to ask to have the mixer cleaned."
I'll leave that without comment.

The smaller your mix, the greater likelihood for error. Maybe Dave would mix and sell it to you.

SP color base isn't really mixed at all as I understand it. The proportioned chemicals are put in bags. You have to do the mixing.
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #61  
Old 09-06-2017, 07:51 PM
Dan Vanantwerp Dan Vanantwerp is offline
Registered User
 
Join Date: Apr 2017
Location: Bozeman, MT
Posts: 103
Dan Vanantwerp is on a distinguished road
It's pretty fascinating to hear about things like that. Good thing they are not in the food industry.

Maybe there is a future for expansion in the batch industry for someone who wants to work with the smaller glass shops. Meticulous detail and some follow up quality control sounds like a much better business model than trying to make cullet. Especially if you target the electric furnace owner and come up with something more element friendly.

I'd like to support those directly responsible for these glasses if Dave (and/or you) are interested. I'm guessing, though, that when you put the effort into making a batch you want to get the direct benefits of your hard work.

It hasn't gone unnoticed by me that you are very particular in determining the amount of screening that an ingredient needs before use. Those little "devil in the detail" things just don't show up in a recipe and can mean all the difference in success or failure. I'm also aware that going to a batch company may be hit or miss in terms of those details.

Ah well...so the adventure begins...
__________________
My furnace setting: 2112
Reply With Quote
  #62  
Old 09-06-2017, 09:32 PM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 19,338
Pete VanderLaan is on a distinguished road
Those are really rather large mixers, holding 1000 lbs or more. If something sticks behind a fin in a big batch, it's probably not that significant. A small batch is. I do ask for a clean mixer using those services and I don't use them often.
I use a small mixer these days from Home depot. For the class, we had two. They hold up to about 100lbs. It's quite serviceable for a small shop and very easy to clean and I'm rather fussy about it if I am making color mixes. If I'm running a cadmium mix I prefer to have a clear mix in between it and any other color. Sometimes I clean it with cullet and throw the cullet away. There's lots of ways to do that. I do think expecting a company used to dealing in tonnage to be even capable of doing the equivalent of craft beer isn't really a reasonable expectation.
I think dave does it in five gallon buckets actually.
And yes grain size really matters. I always use very fine screens on feldspars which I would not have thought would matter. Manganese dioxide is another one. Moisture makes some materials clump more easily than others despite how fine grain they are. I don't like clumps. Sometime try making pancakes using a joy of cooking recipe and when you get to the part where they want you to sift the flour, try it with and without sifting. Guess which one makes the better pancake?

As the German saying goes "Well mixed is half melted"
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #63  
Old 09-06-2017, 11:17 PM
Dan Vanantwerp Dan Vanantwerp is offline
Registered User
 
Join Date: Apr 2017
Location: Bozeman, MT
Posts: 103
Dan Vanantwerp is on a distinguished road
That German saying is pretty darn perfect...

I recall from Dave's notes as he worked through the phosphate issues that he started wetting the batch and found it helped.

Dave, I'd like to know if your latest formulation with low modifiers still likes to be wetted. AND...what is your process for doing so?

Seems like a little water in a batch would make it like a paste...or a pancake batter???
__________________
My furnace setting: 2112
Reply With Quote
  #64  
Old 09-07-2017, 07:10 AM
Eben Horton Eben Horton is online now
Registered User
 
Join Date: Apr 2002
Location: Wakefield, RI
Posts: 3,950
Eben Horton is on a distinguished road
You might not hear from Dave for a while. He has a hurricane to worry about.
Reply With Quote
  #65  
Old 09-07-2017, 07:48 AM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 19,338
Pete VanderLaan is on a distinguished road
the lime is not going to be very happy with being wet and I suspect that to be true of the alumina hydrate as well. They both already have bound chemical water. Between the soda Ash and the lime, if you get it too wet, it comes unmixed. I would try it dry before I did anything like that. I don't wet my batches at all.
The lime wet will eat your skin, fast
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #66  
Old 09-07-2017, 10:21 AM
Dave Bross Dave Bross is offline
Registered User
 
Join Date: Apr 2002
Location: Archer FL(near Gainesville)
Posts: 2,887
Dave Bross is on a distinguished road
OK, first off, no manufactured batch is going to work for phosphates because the calcium content is too high. It's the calcium that turns it into chunky style sandpaper.

Second, It's just not that tough to mix small runs of batch for color. An inexpensive digital scale, a 5 gallon pail and a paint mixer on a drill work great for mixing 10-15 pounds of batch. Check your moisture contents of your materials and either compensate on your calculations or bake it out in the oven in baking dishes. Doing small batches makes the bake it out option a good one. More foolproof. You do need to be exacting on measurements due to the small batch size.

From there you'll have to do a few throwaway runs in your melter to find out what expansion is going to be required for your melter. If you insist on using the throwaways you can add alkalais (1st column of periodic table) if you're low, just keep them off the pot walls until they melt in. If you're high you can try adding zinc or boric acid. You're limited on zinc because it goes opaque around 5-6% and boric acid sometimes makes bad cords.

You'll want to track all of this on a spreadsheet. If you don't have one email me and I'll send you mine.

Water on the batch not an absolute requirement, it just helps keep the dust down. A garden pump sprayer to spray it on the batch at the end of mixing, after it's for sure thoroughly mixed, is my weapon of choice.

Gotta run for the moment. Hit me with more questions and I'll try to dig out a list of the past posts here that might help. As Eben points out, we're in full on hurricane prep and I'll get to all that when I can.
__________________
Art is not a thing...it's a way.
Reply With Quote
  #67  
Old 09-07-2017, 11:25 AM
Dan Vanantwerp Dan Vanantwerp is offline
Registered User
 
Join Date: Apr 2017
Location: Bozeman, MT
Posts: 103
Dan Vanantwerp is on a distinguished road
I'll ask some questions in line to your post...

Gotta run for the moment. Hit me with more questions and I'll try to dig out a list of the past posts here that might help. As Eben points out, we're in full on hurricane prep and I'll get to all that when I can.
Sorry that I forgot you are from Florida...stay safe!

OK, first off, no manufactured batch is going to work for phosphates because the calcium content is too high. It's the calcium that turns it into chunky style sandpaper.
I was hoping to send your latest formula to a batch maker and have them do a custom run (perhaps sans the STP). I just don't have much space to store bulk chemicals. Montana would actually be a good environment as we are very dry here. This is definitely plan B for me. I was looking for permission or to request an intellectual right percentage be established for you with East Bay. Jim mentioned this would be done for Pete's base clear. Sounds like there may still need to be some tweaking though based on the furnace...not a one off formula (addressed below).

Second, It's just not that tough to mix small runs of batch for color. An inexpensive digital scale, a 5 gallon pail and a paint mixer on a drill work great for mixing 10-15 pounds of batch. Check your moisture contents of your materials and either compensate on your calculations or bake it out in the oven in baking dishes. Doing small batches makes the bake it out option a good one. More foolproof. You do need to be exacting on measurements due to the small batch size.
Agreed, I could do this if I had the space for all the ingredients. May go down this route in the future...Thanks for the tips.

From there you'll have to do a few throwaway runs in your melter to find out what expansion is going to be required for your melter. If you insist on using the throwaways you can add alkalais (1st column of periodic table) if you're low, just keep them off the pot walls until they melt in. If you're high you can try adding zinc or boric acid. You're limited on zinc because it goes opaque around 5-6% and boric acid sometimes makes bad cords.
This is the part the that surprises me...I've got a melter that easily goes to 2100...why would my melter need a slightly different mix than your melter to achieve a ~96 COE? Is this that..."doesn't cross the street" thing I keep reading about? What are good ballpark percentages to add (10 lb batch, a little low, add X% Na, K, Li)?


You'll want to track all of this on a spreadsheet. If you don't have one email me and I'll send you mine.
Will do...

Water on the batch not an absolute requirement, it just helps keep the dust down. A garden pump sprayer to spray it on the batch at the end of mixing, after it's for sure thoroughly mixed, is my weapon of choice.
Another great tip but I'd try without first as Pete suggests.
__________________
My furnace setting: 2112
Reply With Quote
  #68  
Old 09-07-2017, 01:17 PM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 19,338
Pete VanderLaan is on a distinguished road
I don't view 2100F as very hot and things are going to have to be coaxed into existence with very small charges. If it was me, knowing what I know, I would in fact start with a bag of SP color base, mix it and do some simple melts. See what problems you encounter at that level. I think they could UPS you a bag of the color base. Its only difference is it contain no nitrates or antimony so it doesn't fine out well. Mess with it. A simple search here will yield up varying silver and copper ruby formulas. I did not care for those colors in the Sp87 I used for a class back in 2013 but I didn't like the feldspar and that has changed to minspar now after the Kona plant burned to the ground.

But get your sea legs first, It's not hard but it's not easy either. Process adherence is your friend. The phosphate, which if Dave or I say is easy, isn't really. You need to have a sense of when it is and isn't working. You tend to know right away. By using SP87 color base, you should have no compatibility issues initially. You'll get them once you become overconfident.
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #69  
Old 09-07-2017, 05:10 PM
Kenny Pieper Kenny Pieper is offline
Registered User
 
Join Date: Feb 2003
Location: Burnsville N.C.
Posts: 779
Kenny Pieper is on a distinguished road
One thing to consider if you use the spruce pine batch color base is that you will need a mixer that handles a hundred lb. When they make this stuff it is measured and thrown in the bag with no mixing. You have to mix all the contents in the bag first. Then you will have to adjust for 1.7lb out of a 98 lb. formula or .6171% of sodium nitrate being missing.
But if you are going to add stp to this you will need to add silica to bring the expansion back down.
Reply With Quote
  #70  
Old 09-07-2017, 06:04 PM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 19,338
Pete VanderLaan is on a distinguished road
I would use Dave's STP formulation first. It should be a separate endeavor from the SP.
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #71  
Old 09-08-2017, 02:32 PM
Dan Vanantwerp Dan Vanantwerp is offline
Registered User
 
Join Date: Apr 2017
Location: Bozeman, MT
Posts: 103
Dan Vanantwerp is on a distinguished road
This is a reply to Dave's latest post from the main forum. I will copy and paste in line to make things easier to follow.

East Bay has tentatively agreed to do a 200# run for me based on the ingredients of Dave's phosphate formula! So I would like to design a "pre-batch" that allows varying levels of phosphate be added to tune the color density.

Dave:
You still have to be able to figure what you're doing, pre-mixed batch or not. The sodium in STPP or whatever ride along components in other forms of phosphorous would have to be compensated for in some way without going beyond certain numbers with the pre-mixed.
It's also harder to take an expansion number down than up.


I was hoping the worksheet would help me to do this. Also, a little help from my friends...as in, if you were to make a veiled phosphate (1%) versus a full-on opaque, what would you do differently? Is the sodium loss in a veiled opal compensated for by adding more alkali? Maybe some salt?


What E&T number do you have East Bay mix it to? Even if you did something like match it to SP on E&T numbers so it had a bigger market you still have to deal with the possibility of the strain points (where the glass sets up) being different enough to cause trouble on compatibility. To not have an embarrassing situation you should batch it and melt it yourself and test the compatibility before going commercial.

I'm not trying to get East Bay to commercialize it. This is for me and anyone else who would like to try the same.

Please help me connect the dots and if I'm wrong in these assumptions let me know:
Pete has melted your phosphate and found it to be compatible with his glass.
Pete's glass is spot on with SP87. Crystalica appears to be the same. Even sounds like it is compatible with Pete's color base.

Get some cheap fireclay crucibles and figure a way to put them in your glory. Other ideas - Mark Wilson used to have a tiny glory with a shallow clay tray in the bottom to melt stuff in. He used the burner from a Turkey fryer to power it. - make a tiny gas color melter like all the guys on youtube building little forges and furnaces. a homemade burner and some kind of refractory and away you go.
This is great for prototyping but doesn't everything change when you move from furnace to furnace to glory to turkey fryer?

I'd like to get the best mix possible identified that gives me the flexibility you think would allow me to get to a compatible glass under a myriad of circumstances. If I need to add a little borax or silica, I'll get some of those to make adjustments. I'd like to start with a commercial batch maker because this is the way it can work for me and my small operation.

Thanks
__________________
My furnace setting: 2112
Reply With Quote
  #72  
Old 09-08-2017, 02:54 PM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
Posts: 19,338
Pete VanderLaan is on a distinguished road
And the old German adage. "A good recipe can't cross the street."

As you vary the phosphate content, you will also change the linear expansion if using STPP.. As you vary the phosphate content you will also make the glass more susceptible to turning into a sort of interesting oatmeal, kind of a slush. I'm sure Dave's seen it. It's not very marketable. It is a glass that burns out so maintaining a temperature range is important, not too hot, not too cold.
*******
A 1% phosphate is a weak phosphate. It might not even strike. You can go up to 5% reasonably. I would not be getting something mixed until I knew more of what I'm doing. I really think you should get your feet wet on easier glasses. Setting goals you cant likely achieve is not conducive to feeling pumped up. if you can't mix in studio, it's damn difficult to really alter things you don't like. People will start installing caller ID for your phone line.
__________________
Where are we going and why am I in this basket?
Reply With Quote
  #73  
Old 09-08-2017, 09:46 PM
Dave Bross Dave Bross is offline
Registered User
 
Join Date: Apr 2002
Location: Archer FL(near Gainesville)
Posts: 2,887
Dave Bross is on a distinguished road
---------------------------------------
Please help me connect the dots and if I'm wrong in these assumptions let me know:
Pete has melted your phosphate and found it to be compatible with his glass.
Pete's glass is spot on with SP87. Crystalica appears to be the same. Even sounds like it is compatible with Pete's color base.
-------------------------------------------
I'll bet Pete had to change the quantities and ended up with a different E&T number to get an exact fit. His melters are considerably more powerful than mine and he melts much larger quantities.
Pete has major skills and even some very fancy tools to check and correct a glass for compatibility.

Pay very close attention to:

" if you can't mix in studio, it's damn difficult to really alter things you don't like. People will start installing caller ID for your phone line."

You are flailing around in the dark until you master the basic skills.

That being said, I'll go at this from the very basics.

Almost any batch will work for this, including something you have mixed by others. The key numbers are no more than 3% calcium or 5% strontium while using at least .4 - 1%, but not more than 2% zinc to help retard the formation of the dreaded surface crystals. Start with somewhere around 2% phosphorous and forget about the veiled, low phosphate percentage stuff until later.

Then, unless you get lucky on the first melt and hit compatibility spot on...

For lowering expansions on future melts add more silica, to raise expansion add soda as per what you find is needed with the thread test and spreadsheet. Don't worry about correcting melts for compatibility while hot for now, just go for the correction on the next melt. That will simplify expansion corrections.

If you want the easiest way just use my recipe exactly as-is. It will work fine and be pretty close on compatibility. Correct it from there if needed.
__________________
Art is not a thing...it's a way.
Reply With Quote
  #74  
Old 09-09-2017, 03:53 PM
Dan Vanantwerp Dan Vanantwerp is offline
Registered User
 
Join Date: Apr 2017
Location: Bozeman, MT
Posts: 103
Dan Vanantwerp is on a distinguished road
I'll bet Pete had to change the quantities and ended up with a different E&T number to get an exact fit. His melters are considerably more powerful than mine and he melts much larger quantities.
Pete has major skills and even some very fancy tools to check and correct a glass for compatibility.


This made a little chill run up my spine
No doubt Pete has major skills. He probably looked at your formula and immediately saw 10 different ways to skin that cat. Still, I'm hoping that for the sake of passing along data that we would all try to give the best synopsis of what was done as possible.
I'm truly a bottom feeder with very little knowledge to give. But if I tell you I did something, I did it exactly the way I tell you I did.

I've been looking for a supplier of Short MT sand all morning and just remembered why I don't want to try and source all these things. East Bay can buy in huge bulk quantities and have a good reputation for mixing. Why not use them?

I ran every batch formula I could find through your spreadsheet last night and just had a blast...by the way, your summation for batch ingredients weight stops before the STP row..need to drag the sum down to B28. I also added a little % phosphate function

Think I'll shut up for a while and get back with results later on. I've got two chalcedony colors going this weekend and it's time to blow. Good luck with the weather and stay safe.
__________________
My furnace setting: 2112
Reply With Quote
  #75  
Old 09-09-2017, 08:09 PM
Dave Bross Dave Bross is offline
Registered User
 
Join Date: Apr 2002
Location: Archer FL(near Gainesville)
Posts: 2,887
Dave Bross is on a distinguished road
Thanks for the heads up on the spreadsheet mistake. Giving that thing away has been a great way to find where I missed.

No need for chills up the spine. Do this:

1 - Melt whatever you decide to do

2 - Check it with thread test - if it's a striking glass like phosphate strike your blob of glass for the thread test the number of times you figure you'll strike it in use then pull the thread. The highest expansion glass is on the inside of the bend.

3 - Each millimeter of bend on the thread test is roughly equivalent to .6 in your E&T numbers

4- Play with spreadsheet, figure how much of either soda (raise E&T number) or Silica (lower E&T number) you'll need to change the E&T to where you need to go to take those few millimeters of bend out of the next thread test.

5 - Add the silica or soda to lower or raise expansion in the next melt.

6 - Melt this and check it with thread test

7 - When it pulls a straight thread then double check it with a polariscope test to be sure the strain points match closely enough. That can be done by putting a blob of it on a gather of your clear, blowing it out a bit, annealing it and have a look at it in the polariscope.

8 - Success!

The fancy toys Pete has are things like a dialatometer that will tell you the exact expansion in ten thousands of an inch and a polariscope with a built in degree wheel so you can put a number to how much strain you're seeing. These are unnecessary to get a good result at the shade tree level (that's us!) but excellent to have if you're selling something commercially and you care about high quality.

If you can't get Short Mountain sand, don't worry, get something else that's been sorted down to 200 or 325 mesh.

The short mountain makes a noticeable difference in clear colors but in opaques you get a lot of leeway because not much light is getting through so a lesser sand quality won't be visible to the eye.

Some folks get lucky on local sand. Rollin Karg gets a great sand at his masonry supplier being sold as play sand. Go figure.

Sorry if I went too far too fast too complicated on this before. It really is a simple process once you do it a few times and it gives you a wonderful level of control.
__________________
Art is not a thing...it's a way.
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 06:16 PM.


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 - 2017, Jelsoft Enterprises Ltd.
CraftWEB.com. Opportunity Network. 2008. All Rights Reserved.