Tech Specs

I've been working w/ window pane glass. Funky stuff is right.
Non-glare, conservation, conservation non-glass, one or both sides...
Slumping/sagging around 1300 degrees F. Full fuse 1525 degrees F.

Mike __ I have used these guidelines with good success. From Gil Reynolds,
quoting Tooley's 'Handbook of Glass Manufacture :
For 1/4" plate glass
1100 F ______ Upper limit of annealing region
1022 F ______ Annealing Point
900 F ______ Strain Point (Lower limit of annealing region)

>Pyrex 7740
>Strain: 950-977F
>Anneal: 1040F
>Soften: 1510F
>Slump: 1500F
>Fuse: 2000F
>Pate de verre: 2070?
>"Working": 2286F
Your figures look perfect.
The only thing that I should add is that they seem to be the lower limit, while the upper limit may be 100F higher.

Here is what I have managed to extract from my data bank:
Pyrex 7740, Corning 7740
Strain: 950-1100F
Anneal: 1030-1200F
Soften: 1508F
"Working":2300-2600F
To your reference, the above figures were extracted from SciGlass 3.5, a glass data bank by scivision, http://www.scivivison.com

6/30/2000
Mike,
I noticed your query about "a handy rough list of temps that apply to various kinds of glass" on the Hot Glass board (the one that Henry pulled your chain about). I've done some work toward such a table, but the person who's done a phenomenal amount in this area is an Australian named Graham Stone, who's written a book called "Firing Schedules for Glass: The Kiln Companion."

The book has over 100 pages of firing schedules and over 100 pages of other technical information. Each firing schedule (and they're for fusing, slumping, glassblowing, and lampworking) has data for a number of different types of glass, ranging from float glass to art glasses (Bullseye, Uroboros, GNA, etc.) to borosilicate, lead crystal, and even furnace glass. (Obviously, some of the info is an approximation due to the variability of the glass.) The book also has tables of annealing data for the various manufacturers and lots of other great information. I'm told it took 5 years to write the book (on top of 25 years experience).

I have a page about the book on my web site at: http://www.warmglass.com/Firing_Schedules.htm

Brad Walker mbwalker@warmglass.com

P.S. Full disclosure: I've never met Graham Stone, but he and I agreed by e-mail to exchange copies of our books. I received his book a few days ago and have been extremely impressed, so much so that I put up the info about the book on my site. The amount of work he has done to create the book is simply staggering.

For information about warm glass techniques and processes such as fusing, slumping, and kiln forming, please visit
the Warm Glass website at http://www.warmglass.com

: kamui I melt fhc too when I can get it I know the supply is low and unless your on the list Santa wont send you any and if your not already on the list I believe you can't get on the list. Anyway I anneal at 490/C strain point 440/C melt at about 2300/F Have melted in an electric furnace but use propane now. Problem with melting fhc is that teddy bears explode if you don't preheat them in an annealer, I preheat my fhc to 550/C before charging stops heads and arms from dripping from the crown. {I think Fenton calls them birthday bears they come with a bag of birthstones that can be crazy glued on to a pad on the bears chest} Smart marketing Fenton has been making these for at least a couple of decades. I understand Fenton will pull cullet in the form of wafers for about .35/lb.
Best of luck watch out for the fit on the C4 and C6 Frank will try and sell you some people have got them to work I lost two days of production on the C4 But that was my fault for not doing the pull test. P.S Those bears really do make wonderful gifts/to your furnace.

Meant to post something yesterday but.. and now no real need to add anything but a little history. The [Spruce Pine] product names are based on the theoretical COE (English and Turner was what we started with). This system was selected in part because it is possible to change the measured COE by using different melting techniques (as <name removed>. has noted a number of times). Dominic Liabino was commissioned to develop our first production formula. There were a few problems moving from the experimental stage to production. The first usable batch that we shipped was the 92. It was never used by very many people as it was a little high but it did get used by some people who had some of the old high expansion Weisenthal (sp?). It is also so high that it fits some of the morreti colors without strain. Thus came the 87. Measures 96-97 when melted but as Pete can tell you it can go from 99-95 with no errors made during production. (Again as <omitted> suggests it is a Good Idea to at least do a pull test to check the expansion when you do a melt.) At the time we were mostly trying to fit the Kugler 61 white as it was used the most of any color. The result is a glass that generally fits the transparent commercial colors along with some of the Zimmerman opaques. The 83 permits the use of some of the opaques but.. Over time we have found that the colors vary enough from production run to production run that once in a while a color that has fit doesn't maybe due to errors maybe due to a change in production. None of which makes anyones job any easier. As a rule, if there is one, each color seems to vary within a range but in general the opaques have a different and lower range than the transparents. Exceptions run rampant. Tom @ Spruce Pine Batch 2000-12-22 Brad Shutes Discussion Board

Float Glass Plant Building  http://www.stewartengineers.com/techfaq.html
Outline of float glass making with spread and ingredient formulas http://www.tangram.co.uk/TI-Glazing-Float%20Glass.html

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COEFFICIENT OF EXPANSION -

A most important specification for glass is the COE (Coefficient of Expansion) yet it is also the subject of the most argument. The COE is the rate at which the glass expands. It is important because if two glasses of sufficiently different COE, usually two colors or a color and a base clear, are fused together, they will crack on cooling.
 The fact of incompatibility can be tested by melting or fusing the two glasses together or the COE can be measured or calculated from the ratios of ingredients in the batch - but that gives two different answers. An additional problem is that the measured COE is done at a much lower temperature (20-300C in the table below) than the temps at which glass develops strain problems. (say 450-500C) The result is that testing must be done before committing certain glass colors to making a piece.
 [European sources may report numbers ten times smaller, using 10^-6 as instead of 10^-7, so 92 is 9.2]  Note that COE is different for F and C (or K) because the change reported is per degree and C degrees are 1.8 (9/5) bigger. Both are length per length, so the units of length given are irrelevant as long as they are the same (not mm/m or in/ft for example.)  List of COE's for metal & other materials Another list with plastics 2008-02-02, -11-30

(Douglas Wiggins) writes:
>Can someone tell me what the coefficient of expansion of ordinary
>cutlery-type stainless-steel is? Just so that we are talking in the
>same quantitative levels:
>Bullseye stained glass has a COE of 90*
>Window and bottle ("soft")** glass has a COE of approximately 86
>Pyrex (Corning 7740 borosilicate) has a COE of 32.5
>Spectrum stained glass had a COE of 106
>*times 10-7 cm/cm/degree C, starting at 300 degrees Celsius -

The Handbook of Chemistry and Physics has a table for pure metals (not the various stainless alloys) which is based at 25C (77F) and uses a different multiplier.
If I convert the ones above to decimals and put them at the left edge of the screen to allow for different text sizes, etc.

Or Aluminum has twice the expansion coefficient of Iron
Glass coefficients fall below most of the metals we are likely to encounter, although Chromium is lower.
Interestingly, most of the metals are well above (120 or more using glass x10^-7) or well below (50,70,60) glass.
Metals with a 90 COE include Antimony and Platinum while Titanium is 85. None are listed at 100 or 110.
Alloys of metals, just as different mixtures of glass, can have widely varying COE.
Remember, these are measured at different temps and can vary with temp.

What does this mean practically?
If a 1 meter long strand of iron (120 COE) were bonded at both ends with a strand of Bulleye glass (90 COE) and the temperature raised 100C. (Making lots of assumptions) the iron would try to be 1.00120 meters long and the glass 1.00090 meters long (1001.2 mm vs. 1000.9 mm or 0.3 mm difference or 0.012 inch.)  If the two were attached so the shorter glass formed a straight line and the longer iron went out to a corner at mid-point - forming a long thin triangle - that point would be 12.2 mm or about 1/2 inch from the glass line.

That conversion of 12 thousandths of an inch difference in expansion to about 1/2" separation at mid-point suggests why COE is important.

[For those who care to check the math, the distance is one side of triangle with a hypotenuse of 0.5006m and a base of 0.50045m - half the length of the expanded iron and glass respectively. The sides of a right triangle are A^2=B^2+C^2 where A is the hypotenuse and B & C are the other two sides and ^ is exponentiation as in spreadsheets. To get a side, the formula is rearranged to get the square root so B= (A^2 - C^2) ^ .5 . So Glass side squared is 0.250450203; Iron side squared is 0.25060036; difference is 0.000150158 and sq.root is 0.012253877 all in meters.]

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Glass Formulas

This portion of the info is provided mostly to show the kind of choices a skilled person can make about glass. One of the areas I am weakest is the theory of making (formulating) glass. MF See also Batch.htm

Posted by Ellen Glassware on 12/8/2000, 6:37 am Brad Shute's Discussion Board [he really doesn't want me to have a link to his board because he thinks posting something like this from his board violates his copyright, but since Ellen is posting something from the Society, it isn't his copyright anyway and I'll keep the link just to give you a chance to see whether the board is still any good.]

Low melting glass recipe from Society of Glass Technology .
sand 55.000 kgs
sodium carbonate 22.000
calcium carbonate 7.000
borax [dehybor] 1.500
potassium nitrate 2.500
barium carbonate 5.000
arsenic 0.4 [the key to good melts] arsenic
for Kugler colour glass
We have melted this glass in the same pot for over 12months in mullite type pot 24inches L 30inches W
crucibles 2 inches thick handmade in Newcastle GB
WE started melting this recipe in 1994 we always melted lead
We hope to live longer.
The Chairman of Hand made Glassware Committee
J Costello

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PHYSICAL CHARACTERISTICS (DENSITY, ETC.)

Glass weighs about 0.087 pounds/cubic inch or about 150 pounds per cubic foot, a density of 2.4 with respect to water, thus 2.4 gram/cubic centimeter, 2.4 kilograms/liter. The density will vary with the constituents, lead glass in particular being heavier.  A site on the internet lists borosilicate glass as 2.3, glass as 2.6 and lead glass as 2.8.  (Other materials)

"Glass never wears out -- it can be recycled forever. We save over a ton of resources for every ton of glass recycled -- 1,330 pounds of sand, 433 pounds of soda ash, 433 pounds of limestone, and 151 pounds of feldspar." Glass recycling site

Water weighs 62.4 pounds per cubic foot, or 1 gram per cubic centimeter, at 4°C, its greatest density. This is the standard for specific gravity, a ratio.

What will pieces of blown glass weigh or how much glass will it take to make a piece?  In this table, the volume of common shapes - a hollow hemisphere and a hollow cylinder - is used to estimate the weight of a bowl shape or a vase shape.  Two specific objects were measured along the way as listed in the table.

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This table of densities started off online in alphabetical order (no longer available.)  It was then massaged, to put it in density order and then the column of relative to glass was added.  (Note the column of density is based on water = 1000 Kg/m³ at its densest - just above freezing.)   Since I work in glass, I thought setting it as the basis of relative density would be fun. Glass data) 2004-02-14  Entries with [MF] in notes were found later out on the web.  Here is a table arranged by material class and by density. 2004-04-26  Here are tables of many more specific gravity figures, provided as an estimate for shipping, including dry, liquid, metals & woods. 2007-01-25 2008-09-19 edit

Melting Glass Cost

In the mid 1980's, the glass industry began to adopt oxy-fuel melting technology encouraged by more stringent air pollution regulations and the ready availability of natural gas. Oxy-fuel melting is the use of injected oxygen as a substitute for combustion air; it can be partial oxygen assist but usually 100% of the oxygen required is supplied. Since 1990, the U.S. glass industry has increased the proportion of oxy-fuel furnaces from less than 1% to approximately 25%. During the same period all-electric furnaces dropped from12% to 9% [ www.energy.ca.gov/process/pubs/all_electric_vs_oxy.pdf ]

Reported power consumption for all-electric glass-melting furnaces range from 790 kWh per ton up to 1,050 kWh per ton depending on the efficiency of the furnace. Therefore, energy costs can range from about $40 per ton to $53 per ton of glass melted at an average cost of electricity of $0.05 per kWh. [1 kWh = 3,412 Btu,   293.1 kWh = 1 million Btu -MF]

In comparison, fuel-fired regenerative furnaces used for glass-melting consume an estimated 4.5 to 7.5 million Btu's per ton of glass melted. Energy costs for fuel-fired furnaces therefore cost about $13.50 per ton to $22.50 per ton (assuming $3.00 per million Btu for natural gas).  [ http://tristate.apogee.net/et/efisgec.asp]

Minimizing the amount of excess air used for combustion, while holding the gas input constant, increases the amount of available heat for melting. For the production melter, proper burner positioning allows a reduction in the excess air from 18% (3.5% oxygen in the flue) to 8% (1.5% oxygen in the flue). The amount of natural gas that is required to maintain proper temperature decreases substantially with even a small decrease in the amounts of excess air used.
It is estimated that an increase in the percentage of outside cullet from the average (20%) to 50% would reduce glass melting furnace energy requirements about 6.8%. The potential savings are 0.51 million BTU/ton of glass, or about 3% of the total energy currently used.  [ http://www.glasscons.com/melting.html ]

One old time factory ad cited calls for people to cut 700 cords of wood. [each being 128 cu.ft., one web site giving 15.6 million Btu per cord for Eastern White Pine and 29.1 MBtu/cord for White Oak]

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The volume of a sphere is 4/3 Pi R³ where R is the radius (half the diameter) and Pi is 3.14159
The area of a sphere is 4 Pi R². For small thicknesses, the volume of a hollow shell is just the area times the thickness.  For thicker shells, the inside volume must be subtracted from the outside volume.

The area of a circle is Pi R² and the volume of a cylinder is the area of the circle times the length.
The area of the outside wall of cylinder is the circumference of the bottom (2 Pi R) times the height (so a cylinder 2R high is 4 Pi R, the same as a sphere fitted inside! thanks Terry Harper) Add the area of the top and bottom for total area of a cylinder.

If 6 wires are bound together, the hole in the middle (7th or core wire) is exactly the same size.
If 5 wires are bound together, the core is 0.707 of the wire size. (to right)
If 4 wires are bound together, the core is 0.407 of the wire size.
3 wires bound together are stable, but if desired a core wire of 0.151 will fit inside.

THICK & THICKER
This table of thicknesses and diameters attempts to combine information from a number of sources (including tables above and below) to give a feeling for thickness.

            The actual thickness of regular aluminum foil is 0.001625cm & the thickness of heavy duty foil is 0.002362cm.

The smallest bit I have seen in a good store is a #80 (0.0135) while the Table shows down to a #97 (0.0059") and a metric to 0.010 mm (0.00039) Alan Notis has been good enough to send me this link http://www.madison.k12.wi.us/toki/codrills.htm which shows sizes down to 107 0.0019  and this site http://www.ukam.com/micro_core_drills.htm with diamond bits down to 0.001 which are to be spun at 150,000 rpm or MORE and have a feed rate of 0.010" per minute or 1" in 100 minutes. 2004-06-28

SHEET METAL GAUGE THICKNESS
The data in this table, which represents industry standard information, was extracted from a table at Sheet Metal Gauge Charts http://www.engineersedge.com/gauge.htm which contains additional information and links to other useful information. [Note that at least for steel sheet, actual gauge is based on weight per square foot, not a measured thickness. More detail]
As a starting point when approximating, I use 16 gauge, which is approximately 1/16th (.0625) in steel.

One story I have seen says that the wire gauge numbers are the relative position of the dies used to pull the wire.  Thus the first die would pull 1 gauge wire (0.2803 in table below), the fifth draws 5 gauge (0.1819"), and so on.  Not all gauges are easily available, especially the odd numbers.  Of course, in the past there were different gauge tables for different companies and countries. 2003-07-31

U.S. Standard Wire Gauge Sizes http://www.graphicproducts.com/supplies/wire_gauge.html

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