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Testing Glass with Polarizing Sunglasses

You can test glass for fusing compatibility with a polarizing sunglass lens. You will also need a sheet of polarizing film.


Testing Glass with Polarizing Sunglasses

Reader Response: The 1985 Boyce Lundstrom seminar

Recent Q&A: An error message from cooling too rapidly

A Kiln Story: The Kiln That Was Named After a Pet

Memorable Quote

News: Paragon Celebrates 30 Years of Ownership by the Hohenshelt Family



The last Kiln Pointer, “Testing Glass with Polarizing Filters,” shows how to set up a light table with two polarizing filters to test glass for fusing compatibility. I used a sheet polarizing film from Bullseye Glass Company.

In this article I will share test results from polarizing sunglasses. Can they be used to test glass for fusing compatibility? My son replaced the lenses of his Oakley Flak Jacket sunglasses. I used the old lenses for the test.

First, I tested a Bullseye 6” x 1 3/4” clear base fused with Spectrum green, white, and blue 1” squares. Two pieces of polarizing film, one held above the other with the glass placed between them, revealed stress between the Bullseye COE 90 base layer and the Spectrum COE 96 squares. The stress appeared as glowing white halos at the edges of the 1" squares.

Sunglass Test #1

I placed two sunglass lenses on a light table, one above the other, and rotated the top one until the green turned dark. Then I held the glass test strip between the lenses. The stress halos were barely visible in the sample glass squares no matter how close or far away I held the top sun glass lens.

Sunglass Test #2

I placed glass test strips on a Bullseye 8 1/4” x 11 3/4” polarizing sheet on the light table. Then I held one sunglass lens over the glass samples and rotated the lens until it turned dark. The halos glowed brightly.

Result: You can use one polarizing sunglass lens along with a polarizing filter to test glass. But two sunglass lenses alone do not appear to be adequate.



The last Kiln Pointer announced the passing of Boyce Lundstrom and mentioned a seminar that he taught at Paragon in 1985. David Kittrell of Kittrell/Riffkind Art Glass in Dallas, Texas wrote, “I remember that first fusing class. We were in one of the caged rooms near the office entrance. None of us knew what we were doing except Judy De Sanders, who filled all the kilns immediately with art.

"We all had a good time at the seminar," continued David, "and I got one of the first Paragon eight-sided fusing kilns shortly thereafter. We still use that kiln today. Think about Boyce and Dan Fenton together in the hereafter. Thank you guys for passing the word.”



Q. Our digital kiln has given alerts that seem to mean nothing, because the kiln continues to do what it was programmed to do. The most recent one this morning showed FTC on a program that we use often without error. It was, however, continuing to cool as it should, so I just shut off the alarm.

A. The FTC error message is nothing to worry about, as you surmised. FTC means "Failed to Cool." FTC appears during a cooling segment and means the programmed cooling rate is faster than the kiln can cool down. To eliminate the FTC message during your next firing, program a slower cooling rate. Since the kiln cools down more slowly than the programmed rate, you may be able to eliminate that cooling segment altogether.



Several years ago a shipping container arrived at the Paragon factory from Venezuela. As the container was unloaded, employees found a live, 24” long Iguana. It had survived for weeks yet still looked bright green and healthy. John Hohenshelt, Jr., the company president, took the Iguana home as a pet for his kids.

Later at a staff meeting, we discussed the name for a new front-loading kiln. “The kiln is smaller than the Dragon,” said David Vives, plant manager, “so let’s call it the Iguana.” This became our only kiln named after a pet.



"One doesn’t discover new lands without consenting to lose sight of the shore for a very long time." -- André Gide


NEWS: PARAGON CELEBRATES 30 YEARS OF OWNERSHIP BY THE HOHENSHELT FAMILY Thirty years ago John Hohenshelt Sr. bought Paragon Industries from Frances Darby, the company founder. Within the next few years, he expanded the company into new markets. In 1985 Paragon made the GF-7B, Paragon’s first glass fusing kiln. That led to the front-loading GL-22A a year later. In 1986 Paragon introduced the KM-14 to the custom knifemaking market. In 1987 Paragon began manufacturing the first economically priced digital temperature controller, the DTC 100.

During the early 1990s, Paragon continued to expand into smaller markets. “We became good at engineering and prototyping,” said John Hohenshelt, Sr. “We designed new furnaces sometimes because we were technically bored. We had an engineer named Ron Grove. To keep him in line, we had to give him new challenges that he could chew on for awhile.”

John Hohenshelt, Jr. became the company president when his father retired in 2001. During the first years under John Jr.’s leadership, Paragon began making new front-loading kilns such as the Dragon, Iguana, and Super Dragon.

Thirty years ago, the Paragon factory was housed in a 40,000-square-foot building. In 1989 the company moved to a 52,000-square-foot building that had once been an eyeglass lens factory.

The 30th anniversary coincides with the opening of a new 20,000 square foot auxiliary building. It is just behind the main kiln factory in Mesquite, Texas. This will give Paragon 72,000 square feet of manufacturing and storage space.

“The new building will give Paragon the opportunity to expand and give us greater options in organizing the manufacturing processes,” said John Jr. “Mesquite is an ideal location for a factory, because it is along a major shipping route and in the middle of the country. This reduces shipping costs and delivery time.”

Since 1948, the Paragon factory has grown from a garage workshop to one of the largest kiln manufacturers in the world. “Frances Darby passed away in June, 2007,” said John Hohenshelt, Sr. “She started Paragon because she wanted to share the joy of ceramics with people who needed kilns. We still follow her original intention.”


I hope you are enjoying the holiday season with your loved ones. My family and I will watch “It’s a Wonderful Life,” one of our annual traditions. I enjoy the movie more every time I see it.

Thank you,

With best wishes,

Arnold Howard Paragon Industries, L.P. – Better Designed Kilns 2011 South Town East Blvd., Mesquite, Texas 75149-1122 Voice: 972-288-7557 & 800-876-4328 / Fax: 972-222-0646 / / /

PRIVACY NOTICE: Under no circumstance do we share or sell your email address.

Copyright 2012, by Paragon Industries, L.P.

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