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Removing Glaze or Glass from a Kiln Shelf

Hold the putty knife at a shallow angle and gently tap the handle.


Removing Glaze or Glass from a Kiln Shelf

Recent Q&As: Element wear during slow cooling; enameling on brass

A Kiln Story: Guardian Angels and the Kiln

Memorable Quote

News: Paragon Receives Texas State Grant for Employee Education



Overfired glass or glaze can embed into the surface of a bare kiln shelf. If the shelf has been coated with kiln wash, you can usually pop off the contaminant without damaging the shelf.

Place the shelf on a surface that has been cleared of all debris, such as a flat sheet of cardboard on a table. Wearing clear safety glasses, hold a putty knife at a shallow angle against the edge of the glaze or glass. Lightly tap the putty knife handle to dislodge the contaminant. It should come right off along with the kiln wash underneath. Recoat the shelf.

If the contaminant has penetrated into the shelf, removing the contaminant may leave a gouge in the shelf. You can sometimes smoothen a small gouge with a heavy application of kiln wash. After it dries, sand the kiln wash. This is only a temporary fix. If you turn the shelf over to fire on the other side, first remove all the contaminant. Otherwise it could melt during the next firing and drip onto ware below.

For future firings, make sure the kiln wash on the shelf is thick enough to protect the shelves. Glaze and glass can work through a thin coating. And, of course, monitor the kiln to avoid an overfire. The higher the temperature, the deeper the glaze or glass can penetrate a shelf.



Q. How much does slow cooling of ceramic ware reduce the element life of a kiln?

A. Controlled cooling, where the elements turn on periodically, reduces element life, but the amount of wear varies depending on the kiln wall thickness and the length of the controlled cooling. (A thick-walled kiln can often achieve the effects of slow cooling without even powering the elements during cooling.)

Firing the elements at high temperature adds wear to the elements. The more they struggle to maintain a high temperature, the faster they wear. Controlled cooling is much easier on elements than high firing.

To get the most out of your elements, begin the controlled cooling at the optimum temperature and no sooner, and maintain the controlled cooling for as short a period as necessary. You can determine the ideal slow cooling profile by testing glazes in a small kiln.

Q. I was wondering how to enamel on brass. Can I use the same enamel that I use on copper?

A. Copper enamels will not work on brass. The coefficient of expansion is not compatible. The result will be that the enamels chip, crack, or flake off the piece.

There is a product called gilding metal which is 95% copper and 5% zinc. This is technically a brass product, and it can be enameled, although only for two or three firings. After that the enamel starts popping off. But gilding metal should not be confused with the sheet brass one might find in a hardware store or other sources. Gilding metal is made specifically for things like badges and has a much higher percentage of copper than other types of brass.

At one time Thompson Enamel made a line of enamels specifically for brass; however, they discontinued it many years ago. – Answer on brass enamels by Pam East, author of “Enameling on Metal Clay.”



David Kittrell of Kittrell/Riffkind Art Glass in Dallas, Texas wrote, “We had a customer who took a class ‘elsewhere’ and was shown a sort of raku using newspaper in the kiln with her glass. When she said ‘newspaper in the kiln,’ everyone in my studio went silent--I can't even remember hearing the radio. She had the floor.

“Then she explained that she was firing her own kiln at home and decided that if a little paper was going to do what it did, well, why not a little more for a more dramatic effect,” David continued. “She got her dramatic effect alright when she opened the lid at 750 degrees F to see why it was smoking so much. The new air hit the supercharged fuel, and a flare went up between her and the kiln.

“Fortunately, she wasn't hurt, but she said she sure ‘took a lesson’ from the firemen that came. Lessons learned. Guardian Angels confirmed and on duty.”

To share your own kiln stories and adventures, send an email to . Please include your name, city, and state where you live. I look forward to hearing from you.



"Your thoughts are the architects of your destiny." -- David O. McKay



At Paragon we have always valued education. For many years, the company has reimbursed employees for courses related to their jobs. Last year Paragon received $82,000 in competitive grant money from the state of Texas for employee education. This year we received a $25,000 grant, which pays for community college courses.


Two weeks ago my son and his wife moved home from Dover Air Force Base. After they arrived in Mesquite, the glaring sun distorted the plastic case on a TV set in the back of their pickup truck. But the TV, with cracked and distorted plastic cabinet, still works!

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 2011, by Paragon Industries, L.P.

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