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Ron Mynatt 08-06-2017 02:43 PM

Factors for calculating LEC English and Turner
I am looking to confirm the English and Turner Factors for calculating the LEC for my recipe.Since I have been told the lithium carb factor is too low I thought I should double check the other ones to make sure.I thought I got them from Glass Notes 3rd edition but I gave that copy away .I've called the Library at Corning but have not heard back from them.Does anyone have a source for them?

Pete VanderLaan 08-06-2017 05:09 PM

you did get them from glassnotes 3rd. Croucher established the corrected factor based in Appen which bears out in a physical measurement, which is how it was done in the first place. You'll find it in Glassnotes 4th.

What you won't find in the 4rh is the factors for metallic oxides. They're simply hopelessly totally wrong and are based in a completely different temperature range in a study done for the enamelling industry back around 1925. Paul Manners put those factors in an article he wrote for Glass Magazine called "custom made to Fit" in or around 1977. That was the first error. Then, Henry canonized it putting it into the 3rd edition.

I suggested that he remove it based on the evidence, and he did.

There simply are no factors for the colorants and never have been.

Peter Bowles 08-06-2017 08:11 PM


Originally Posted by Pete VanderLaan (Post 136086)

There simply are no factors for the colorants and never have been.

That would make a fascinating Masters project

Pete VanderLaan 08-07-2017 08:31 AM

The reason is simple. Industry simply does not laminate color to clear. They have no interest. Studio glass scarcely has any interest since 98% of studios use color rods. The economics aren't there and those of us who do make color pretty well already know what we can and can't get away with.

So, you're right it would make an interesting study

Sky Campbell 08-11-2017 06:36 PM

Didn't Brad Shute develope a spreadsheet just for this purpose?

Pete VanderLaan 08-11-2017 07:08 PM

he got his spreadsheet from me. The factor for lithium was what John Croucher worked up from Appen. I use it. The others are fine. There are none for metallic oxides.

Ron Mynatt 08-12-2017 03:52 PM

I have a copy of Brad's and Dave B. spreadsheet and Ken Kubiak has corrected lithium to Pete's number.He has added spodumene,and strontium,Corning has gotten back with us so there is more info there.Overall Ken's spreadsheet seems a little easier to work with.

Pete VanderLaan 08-12-2017 05:24 PM

Normally, the colorants are simply not going to affect the expansion if they stay in ranges that hover around .10% as a max. There are indeed colors that can exceed that and it's a rare bird where you don't have to compensate with some alkaline flux but that won't usually exceed .10 percent either with a few notable exceptions. Go above 1% and you can see problems. You have to test. If Corning actually had legit co-efficients which were not the W&S numbers, I'd surprised and then pleased. I mentioned the lithium since it was such a significant difference. You really have to consider what it is you're trying to do. Making colored glass is one thing, making color rods is quite another. You can wind up making stuff that is only kinda sorta glass. The enamels can fall below 50 percent silica.

I get a fair idea about the general interest in this by looking in on the board dedicated to color. It's really marginal.

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