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Tom Clifton
02-13-2012, 03:02 PM
What would you expect the current cost of materiels for Moretti Compatible Batch (http://talk.craftweb.com/showthread.php?p=26587#poststo) to be. As a complete novice, I started looking at Fischer Scientific and Sigma Chemical and was astonished at the prices per KG of some of these things...

Also - where do you purchase supplies from?

Pete VanderLaan
02-13-2012, 04:02 PM
I would expect the costs to be around $1.00 lb for the materials. It would be a high barium, high lithium batch to get up in the 104 L.E.C range.

Prices for small quantities are just really bad. I get some materials from UNIVAR but it's always 50 lb bags and I start getting better pricing at 20 bag breaks. They have been awful on Soda ash and potash lately and I am getting it elsewhere but I can't disclose the source since the source doesn't want to be in that business, sorry

Standard Ceramics in Pittsburg is a metallic oxide source as is US Pigment. Places like Seattle Pottery have everything but bend over. What you need is an industrial chemical house. Get Silica from your local pottery. I get mine from Short Mt Silica in Tennessee and its great stuff. I get at least a ton at a time. Feldspars are pottery supply things as is calcium carbonate, known more as whiting or marble dust. Laguna Clay is another possibility. Refer to the sections on raw materials in Henry's book for that. Stay out of reagent grade chemical houses. ( But my lime is Kosher!)

It's a seek and ye shall find kind of thing.

Tom Clifton
02-13-2012, 05:28 PM
As my interest is largely academic and batches are likely to be small, few and far between this is going to be interesting... What good news there is that I'm practically sitting on top of the St. Peters Sandstone. (Crystal City, MO is 30 miles south of me) I can go to a friends back yard and dig up all the nice white silica sand I want. The Ozarks are full of limestone and dolomites. It's the "other stuff" that becomes problematic. Thank goodness there is pelletized batch out there.

Pete VanderLaan
02-13-2012, 05:53 PM
Don't go digging sand Tom, just buy it. Years ago I did the native materials route with Dale Chihuly. I did most of the digging and screening and it was winter. We did make glass. It was certainly organic. It wasn't a 104 moretti compatible material. My fingernails hurt.

Get your materials at a pottery supply in St Louis then. They will have most things at a fair, almost, maybe , price. Go back and read Henry's 4th edition of "Glassnotes". I put a list of the things you have to have in the section I wrote on glass batch. It's all there.

Dave Bross
02-13-2012, 06:38 PM
Second that on pottery supply outfits any more. I used to buy from the big chemical houses too but they obviously don't want small business any more.

Shop the pottery suppliers, assuming more than one nearby. There can be big differences in $$$$. Buy enough quantity to get a decent price. I'm in north FL so I buy often from Axner near Orlando but sometimes ship 50# bags from Davens in Atlanta and come out ahead.

Forget "going native"

You want materials with known composition for consistent results.

Short Mountain sand if you can get it.
The other thing about the sand is that you want very fine mesh...200 at the most. 325 is better.

Search the archives here for info on what you're thinking of doing. It will cut your learning curve down immensely.

I have an E&T calculator you can have.
Search the archives if E&T is an alien term. it's English and Turner.

I would guess you are looking at around 35 - 40 cents per pound to batch your own these days assuming major materials (sand, soda, lime) are bought in 50# bags, more like what Pete said if buying in small quantities.

Tom Clifton
02-13-2012, 09:07 PM
Years ago I did the native materials route

You hit the nail on the head.... All too often pride comes before common sense. Also, I keep getting jolted to reality when I realize that you guys work at a completely different scale than I do. In my world, Lithium Carbonate is a drug used to treat BiPolar Disorder 100mg at a time. You use it by the shovelful...

I just googled Seattle Pottery, and find that the prices are quite agreeable. Point well taken on buying things locally when possible. Little point in paying $50 freight for $10 of sand... I already found that to be the case with Frax - HiTemp is here in town & I'm not paying freight..

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EDIT
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Just had another Duhhh moment... I drive by Krueger Pottery Supply on the way to work every day. Quick check on line shows that they have nearly all of the bulky stuff. One quick question regarding silica. When I look for fine mesh stuff it is generally 200 or 325 mesh 'flint'. Is this suitable?

Pete VanderLaan
02-14-2012, 03:05 AM
200 mesh is actually better than 325 mesh. 325 tends to clump and takes on moisture. Screen it anyway. Screen everything. If Seattle Pottery looks reasonable, things are worse than I thought.

Tom at High Temp in Fenton is a good refractories source.

Don't forget moisture content, it's important. seal off alkaline fluxes in ziplocks.

None of us use lithium by the shovelful. The unconscionable ones use borax by the shovelful and destroy our furnaces.

Well mixed is half melted.

Don't try to mix five pound batches. The laws of significant figures start to come in to play.

Dave Bross
02-14-2012, 05:30 AM
I'm going to agree and disagree with Pete.

325 mesh melts a bit quicker but It can have the problems mentioned.

Agree on all except mixing small batches. He's absolutely correct about errors going exponential in small batches but with careful measurement and baking the moisture out of everything you can do it successfully.

These may help:

http://talk.craftweb.com/showthread.php?t=2581

particularly:

http://talk.craftweb.com/showpost.php?p=82182&postcount=5

Knowing what we know now about furnace damage I would drop the borax. It changes the expansion so little you don't need to recalculate.

Ask the pottery supply if "flint" is indeed sand.

Pete VanderLaan
02-14-2012, 06:12 AM
I actually prefer 140 mesh silica. It is too hard to get. If you are going to do tiny batches, do them in grams. If you are going to do tiny batches, moisture content becomes absolutely critical. If you are going to do tiny batches have a calibrated scale and have it calibrated professionally once a year. If you are going to do tiny batches, mix forever. As to borax, I always recalculate no matter what.

Better you should do a larger batch and then take portions of it and add colorants . That way at least the base is consistent.

Small melts are fugitive in my experience. The surface area of the pot comes in to play as well as the proportioned ratio of refractory to glass. Your results will vary.

Hugh Jenkins
02-14-2012, 11:48 AM
A small test melt can be a fair indicator of being in the ballpark without wasting large amounts of material. But, calculating, measuring and mixing well with less than 10# of batch is sketchy. At that scale you are at least working in whole grams down to the .1% accuracy.

Dave Bross
02-14-2012, 11:57 AM
Agreed on the 10 pounds minimum...and the reasons.

Tom Clifton
02-14-2012, 03:37 PM
You guys just answered a half dozen questions I was going to ask! Dave, in regard to your Moretti 104 like batch. I am almost paranoid about heavy metals. What happens if I omit the antimony? (I do know that with proper ventillation & respect It's OK, but still...)

Also - a comment on scales. My own equipment is a 50lb digital by gram and a triple beam blance to 2.5kg by .1gram. I have and use a reference set (10mg to 2kg). All quite old and none of it is anywhere near tracable to NBS, but I consistently get the same wrong answers all the time:) Guess I should probbly take it in and get it stickered...

Again - thanks to all for the incredible support!

Pete VanderLaan
02-14-2012, 04:49 PM
You really have to accept the following notion: Making glass from raw materials is not an entirely safe operation and never will be. If you have irrational fears of the chemicals you will make mistakes based simply on your fear. It's a lot like people I know who are afraid they will fall off of horses so the horse senses it and they fall off.

What you need to do is to play it safe. Wear gloves. Wear an organic vapor respirator. Have very good exhaust in your mixing room and at your furnace and if you can't do that stuff, then melt cullet- really. I do not know of a non toxic glass in some way. You simply can't leave out the antimony. It is the principal fining agent in the glass. The substitute is Arsenic, normally used in lower melting temp glasses with lead. . In reality the safer the glass you can make, the less interesting it is. Sand, Soda Ash, and lime indeed make a glass. It's a common combination for bottle glass. If you want luster, you need potassium, you need barium or you need lead. If you want a glass that isn't brutish and short, you need potassium, you need lithium, you need zinc, you need lead or a combination of some of those metals. This is not entirely a kid proof playground.

Dave Bross
02-14-2012, 05:26 PM
Nice rant!

And while we're on antimony....you have to melt the glass in something that can get beyond (hotter) the valence switch in the antimony, which happens at 2170F.

That's what gets rid of the small bubbles without waiting for days (if ever)while the bubs float to the top. I had the same thought early on and tried without antimony. Ended up having to make something where lots of bubs weren't an issue with that melt.

When the antimony switches valence on the way back down in temp. the bubbles will be absorbed.



What you have there for scales is fine. Having the weights to check is great.

All through this process we only need consistency within our personal little melt world.

Even if the scales are wrong, as long as they are consistently wrong in the same way and you only use those scales you would be fine.

The batch you finally melt and tune in to your furnace will not "cross the street" and be the same thing elsewhere.

you can't anneal the glass by setting to a temperature someone told you would work, you have to slump a cane to know what YOUR anneal temp is in your annealer. It will be different in another piece of equipment or elsewhere.

We can give you approximations but you'll get very good at test and tune because you want first class results and fewer fails.



I mix 10# batches in a 5 gallon plastic pail with a paint mixer and a drill. I use a dust cover on the pail made from a plastic bag with the shaft of the paint mixer poked through it. I mix it outdoors in case something goes very wrong.

I use rubber gloves and respirator and much caution not to raise dust through the batching and mixing process. If I do spill stuff I do wet cleanup for the dust issues.

As you can see, some compromises from Pete's ideal situation. More "what's your risk to reward ratio" stuff.

Here's some old pics of batching with the mixer. Back then that was a tiny room dedicated to batching so I didn't worry about cleaning up the spills, I just didn't go in there without respirator and gloves:

http://www.davebross.com/GlassTech/batching.html

Tom Clifton
02-14-2012, 07:08 PM
If you have irrational fears of the chemicals .... This is not entirely a kid proof playground.

Not a rant - just a very simple statement of fact. Sort of like his answer to "safe" flourine a week ago.

Paranoia may have been too strong a word. Perhaps the next level beyond a healthy respect. I think St. Louis must be the national capital of lead poisoning. Between the crumbling buildings in the city to the 4 wheeler playgrounds on the mine tailings south of here we are constantly made aware of this. (Also to some small degree my own stupidity back in the 70's burning paint (lead based)off of houses before painting.

Two more questions. The antimony is in the form of antimony oxide? The Potassium Nitrate is there for the nitrate not the potassium, and sodium nitrate can be substituted as long as I tweak the potash and soda ash for the increase (molecular weight) of sodium and the decrease of potassium?


Videos from Mark Lauckner on the way. I am going to run with the big dogs - just not 400 lbs at a time...

Dave Bross
02-14-2012, 08:08 PM
The rant comment was humor.

Yup, antimony oxide

sodium or potassum nitrate are fine. Sodium is way less expensive and yes, it's just there for the nitrate.

I think Mark only has videos for the 30 pounder any more? Mark's info is great but do you need a 30 pound furnace? We're talking serious money to build and run as hobby furnaces go.
Mark used to have videos on a ten pounder which was what I started with. Might think about that if he still has those?

The glass goes funky in a pretty short time in a small furnace. You don't want more than you can use up in a couple of days. Less time than that if using cheap pots.
Thinking back, if you wanted to use good pots I don't think anyone makes one to fit Marks' old design.

Eben Horton
02-14-2012, 08:46 PM
This is how you make Morretti compatable batch.. its really complicated.

dial (828) 765-9876

order some :)

Pete VanderLaan
02-15-2012, 06:37 AM
Do not ( as an example) use 2lbs of sodium nitrate as a primary sodium source instead of getting the sodium from sodium carbonate. There is a volition factor to each in your search for sodium oxide but I have seen formulations with the nitrate being up in the 5-7 lb range as a sodium source and it will rip the living snot out of your furnace.

As an example, in 75 lbs of my clear batch, I have 113 grams of potassium nitrate and I have 75 grams on antimony oxide. That's all the fining agents you would need.

I have also seen formulas at 75 lbs that have 5 lbs of potassium nitrate in them. Those are the people who help make my boat payments each month.

Just stick to basics. Silica around 68-72%, alkaline fluxes no more than 18%, stabilizers at 8%, Alumina from feldspar would be alkaline fluxes divided by 8. This does not total 100%. The rest is a military secret of the Romans. Screen everything. Really. Window screen is fine, even too fine.

Pete VanderLaan
02-15-2012, 06:43 AM
This is how you make Morretti compatable batch.. its really complicated.

dial (828) 765-9876

order some :)
*********************
If everyone followed this advice, we would, in a single generation lose a remarkable amount of knowledge. Glass making is built on gaining and losing secrets for really bad reasons. From '62 to 68 just keeping it on a pipe was the main problem but by '68 there were people really digging for more sophisticated knowledge. In 1968 we were starting all over again because we had lost so much since the great depression. As a group, we know significantly less than we did in 1988. The entire process is continually being dumbed down and I watch it happening. I applaud Tom for just being alive and curious. We need more of his type, not less.

Where do you really think this will go when the kids who approached this like it was the renaissance, die? If we contribute for ten more years that will be stretching it. . The old guys who still know this stuff are getting pretty creaky and I'm certainly one of them.

Tom Clifton
02-15-2012, 12:16 PM
I think Mark only has videos for the 30 pounder any more?

Marks current design is actually 40 lbs. Email from Mark indicates that his furnace is scalable down to 8 - 15lbs by using one element instead of two and shrinking the size proporionally.

Also - any furnace I build isn't likely to be a clone of anybodys plans. Information on what doesn't work (and why) is perhaps of greater value than what does work. Input from Henry, Dudley and Mark (don't forget Steven Bishop "Elements, Relays, and Controllers" thread) all figure into the overall plans.

Change Gears...

Variacs. Great things within their power limitations. Just like changing the transformer taps for an aging silicone carbide element, they can increase (or decrease) voltage for wire elements. You ask why wire elements last longer with a variac than with an SSR? Look no further than a lightbulb rated for 1720 hours. If you never turn it off, it lasts twice as long. Turn it on and off every 2 minutes you will be lucky to get a week out of it. (Same goes for compact flourscent lamps - read last months Consumer Reports). It's those changes in temperature that cause expansion and contraction of the elements that makes them break.

Ranting

Pete, you know the players here far better than I do. I take most off the wall comments as "English Humour". I was going to post a "Down Boy" remark, but then I thought better of it when I went back to my image of you being the crusty old guy (not quite a curmudgeon, but close) that isn't shy about speaking his peace, and turning up the burner a few notches to get the point across. I suspect you are a terrible poker player...

Sodium Nitrate vs Potassium Nitrate

Not only cheaper but much easier to get. Department of Homeland Security seems to think anybody that buys saltpeter or fertilizer is a mad bomber now days. You can go to Lowes and buy "stump remover" but the guys that build extreme model rocket engines and fireworks for a hobby will tell you that this stuff isn't always what it is supposed to be...

So - Pete, yes - if somebody uses 75lbs of nitrate in a batch they must be having a subliminal desire to enjoy the fourth of July in their shop... I get it...

Pete VanderLaan
02-15-2012, 12:58 PM
Getting oxidizers is a challenge. I have a 20 year supply. For me it's not an issue at 113 grams at a time. As far as making good glass: you aren't going to make an omelet without breaking eggs.

Richard Huntrods
02-15-2012, 01:14 PM
People seem to be either up or down on Mark's furnace design. You just have to remember that if you build one, it's YOUR furnace. You are free to make changes to suit what you have.

I think the crucible is still available from EC. It's not at all what Pete likes ('cause it's just a square bottomed cylinder), but it does work.

There are a couple of things that Mark really nailed with his design compared to so many other wire furnaces.

1. He uses a LOT of insulation backing the inner firebrick. As discussed in other threads, there's a thermodynamic limit as to how much insulation you need, but most furnaces are pitifully under-insulated. Especially those based on kiln designs. He also skins the furnace in expanded metal mesh, NOT sheet metal. Sheet metal skins are a great way to get burnt using the furnace, but are not a great way to skin them. Painting the expanded metal contains the insulation fibers as well.

2. He uses alumina board to cover the top of the heat chamber, with a close-fitting hole around the crucible (packed with frax) to allow gathering. This is covered with the lids (one maintenance, one for access to the gathering port). Covering the heating chamber with alumina board in this fashion keeps the glass vapors away from the elements. This is (in my opinion) critical for decent element life.

I think the other elements (size of element, type of element groove, controllers) can be adjusted to suit what you can buy. The design also would scale pretty well to a round-bottom pot and up to 75-80lb. I would not go above 75-80lb in a wire melter, and would say 100lb would be the absolute upper limit for these things. But that's just my opinion.

Cheers,

-Richard

Dave Bross
02-15-2012, 01:26 PM
Allright!

Tom is funny...a la dry humor. That's good! You'll be needing to laugh at yourself at some points in this project.

It's always good fun to poke Pete. You get way more knowledge nuggets and great stories that way. Sort of like pearls from an oyster due to irritation.

I've been wondering about calcium nitrate. Easily available via the pottery supplies without having the patriot act invoked on you. I'll have to look up the formula and see if it packs as much oxygen.

Variacs, yeah, expansion/contraction was my best guess. The increase in element life is just amazing.
Variacs are like a Big Mac....you can rack 'em and stack 'em....and no, I don't want fries with that. Sometimes you can even score them on Ebay ready made in a stack. Run however many elements per variac that each one will tolerate. What I don't know, and would love to, is if you can series or parallel connect multiple variacs for more amp capacity.

As far as what works or doesn't for furnaces I would refer you to that search button up top in the header here. A good term to start with would be "wire melter"

Got a grip on E&T yet?

Tom Clifton
02-15-2012, 06:13 PM
Variacs... What I don't know, and would love to, is if you can series or parallel connect multiple variacs for more amp capacity.

Got a grip on E&T yet?

As a variac is just a transformer, the current it can carry (and power delivered) is limited by the wire guage and magnet saturation of the core so putting them in series - no. Parallel connections, technically yes - but only if the output voltage is set exactly the same. If output voltage is different, the one with the lower voltage will suck amps fromm the one with higher voltage - limited only by the effects of internal resistance of the unit to the extent the higher voltage unit "loads down" and they equalize. So, for all practical purposes -Parallel no, but Stacking (one variac per isolated load whcih could be more than one element) is OK.

Dry humor, and poking fun at ones self

That is a survival mechanism I have developed from many rears of living in the Clifton Household. If you are quick enough(and first) to admit the folly of your ways, abuse received from a large family of (eager) brothers and sisters is substantially reduced

Pete Poking

Is that an extreme sport similar to alligator wrestling?

Search button

I am well familiar with that here and elsewhere. The biggest problem I have with it is that I am too easily distracted and wander off into chatty messages like this and get no real work done. At least with books and instructional videos - they are more focused on a given subject, permit one to make all the dumb mistakes and arrive at incorrect conclusions without talking back or saying "I told you so"

E&T

I seem to be alphabetically challenged. What is it? (I will probably say Duhh.... as soon as I post this...)

Peter Bowles
02-15-2012, 06:41 PM
English and Turner

They give numeric values to a bunch of materials to calculate expansion....take a peek here

http://glassproperties.com/expansion/ExpansionMeasurement.htm

and there is plenty more of this out there


If you are looking to develop a palette of colours in small batches, have a look at the way ceramicists do triaxial blending. Its a quick and accurate way of getting in the ballpark before commiting to larger melts.

Hugh Jenkins
02-15-2012, 06:45 PM
For some history on the search for optimum nitrate and antimony in different furnaces read "Crystal melting at Penland" in the Hot Glass Information Exchange. If you don't fall asleep, you might see how to approach finding what would work in your situation. No need to use more than necessary for either of these components.

Dave Bross
02-15-2012, 08:12 PM
Getting back to Toms' basic education....this is long as hell but maybe one of the most important things you'll read on here if you're going to try to match glasses:

http://talk.craftweb.com/showthread.php?t=3397

Sort of a prelude to what you'll be doing with the E&T numbers.

Tom Clifton
02-15-2012, 08:54 PM
Substituting Nitrates

Just got off the phone with my Son-In-Law (chemist by trade). The discussion was about nitrates as oxidizers.

Ammonium nitrate NH4NO3
Sodium nitrate NaNO3 One nitrate per sodium
Potassium Nitrate KNO3 One nitrate per Potassium
Calcium nitrate Ca(NO3)2 two nitrates per calcium strongest bond, strongest oxidizer

He said all four will work (ammonium will stink like crazy), calcium nitrate has two nitrates per calcium and has twice the oxidizing power so only half as much is needed. One difference is the strength of the molecular bonds between the metal and the nitrate. (discounting ammonium nitrate) Sodium Nitrate has the weakest bond and works a lower temoeratrue followed by Potassium then Calcium at the high end.

Pete VanderLaan
02-16-2012, 04:12 AM
you want the weak bond which is why the calcium isn't used. You will not be able to acquire ammonium nitrate easily thanks to tim McVeigh. Use Sodium nitrate. It works fine but make sure the sodium is included in you expansion factoring. I use potassium because I will take all the luster I can get and I won't get it from sodium. Potassium also takes on selenium in a far more attractive way than sodium does. Cad/sel glasses are always in a zinc/potash base so don't fight with it.

Dave Bross
02-16-2012, 05:26 AM
Now Pete, no one has tried the calcium yet.

It might work just fine, it's dirt cheap and it's available at pottery suppliers everywhere.

I sound like a pitch man on a late night infomercial. OXYCLEAN!
Hey, maybe it works in the laundry too.

Tom,

Don't be alarmed by the complexity of the page Peter Bowles posted. We're going to simplify that immensely for you. Likewise the long COE thread I posted. It rambles and rambles but there is important history and tech in there that will enhance your understanding of what you do later...and make you really appreciate a simplification of it all.

You have a chemist in family! Excellent!

Thanks for the info on variacs. I know just enough about electricity to be dangerous. Likewise chemistry.

Looking through the archives I don't see a really good basic explanation on E&T so I'll work on scratching that out while you digest the monster thread on COE.

Pete VanderLaan
02-16-2012, 06:42 AM
Given how little nitrate is used in the glass formulation in the first place, price is not going to really be relevant. Usually when something has been avoided for over 150 years, there is a good reason. The Germans would try anything once.

Eben Horton
02-16-2012, 08:45 AM
Pete, I was trying to add a little humor. I agree with you.

Pete VanderLaan
02-16-2012, 10:52 AM
That's good. A lot of people really feel that way. It is currently how schools are being run. It's awful.

Dave Bross
02-16-2012, 12:26 PM
All the credit for this thought goes to Tom Fuhrman:

We know nothing about the financial health of all these companies that supply ready made glass supplies. They're privately owned and there is no financial info available.

What happens if you wake up one morning and your supply company is gone?

Can't happen here?

Check this out:

http://www.newyorker.com/talk/financial/2012/01/30/120130ta_talk_surowiecki