The top element glows, and the center element is almost dark. This is normal. Not all elements are designed to glow brightly.
Should All Kiln Elements Glow?
Recent Q&As: Heat damage on relays; repairing a lid hinge
A Kiln Story: The Forgotten Kiln
SHOULD ALL KILN ELEMENTS GLOW?
You would think that if a kiln heating element remains dark or glows only faintly, the element is defective. Common sense tells us that elements should all glow the same throughout a kiln. But this is not always the case.
Some time ago I positioned pyrometric cones on a kiln shelf in front of a center element and fired the kiln to cone 7 (2262F / 1239C). The kiln interior glowed bright yellow, yet even at that high temperature, the center element barely glowed. The kiln wall behind the witness cones was the same color as the cones, rendering them difficult to see.
After the kiln cooled, I positioned cones near the top of the kiln instead of the center. Again, I fired to cone 7. This time, the heating element behind the cones glowed brightly and silhouetted the cones, making them visible as an outline at high temperature.
In some kilns, the top and bottom elements of a kiln are designed to produce more heat and glow brighter than the center elements. This is because the firebrick top and bottom require more heat than the center wall section. This is why the center element in the experiment above was not bright enough to silhouette the witness cones.
On some glass kilns, the main heat is designed to come from the top, so the side elements do not glow brightly. This is normal.
If you suspect that an element in your kiln is defective because it doesn’t glow, place a small piece of paper in each element groove. Fire the kiln to around 250F / 121C. Scorched paper indicates that the elements are working.
If an element heats but does not glow, do not be concerned as long as the kiln is firing to temperature and you are satisfied with the ware inside the kiln.
Q. The relays on my kiln seem to wear out too often. The last relay I replaced has a melted spot.
A. Examine the relays that you previously replaced. Is the heat damage on those relays in the same location as the heat damage on the relay you are now replacing? If so, you have found the problem: a loose push-on connector.
The push-on connectors must be tight. Loose connectors burn up new relays, leaving heat damage near the terminal. Tight push-on connectors are difficult to slide off the relays.
Q. The lower portion of my lid hinge is not secure. I plan to drill the metal adjacent to the old holes and put in another set of screws. Will that work?
A. I don't know which kiln model you have, so this advice is general: Drill the holes so that the bottom hinge section allows the lid to have play. (Hinge holes are slotted. When installed properly, you will have about 1/8" of play at the back of the lid.) This compensates for firebrick expansion. If the hinge does not have play, the front of the lid will rise about half an inch at high temperatures.
A KILN STORY: THE FORGOTTEN KILN
Terry Brake of Diamond, Ohio wrote, “I graduated in 1977 and bought my kiln right after college. The kiln lived in the basement for 16 years and then the crawl space of a new house. I finally took the kiln out and put it in a studio my dear husband put up in our yard, never expecting the kiln to work after all the damp and dark years. It's been firing for three years now, antique that it is--no controller, just a pyrometer, and it's just great.”
“It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood; who strives valiantly; who errs, who comes up short again and again, because there is no effort without error and shortcoming; but who does actually strive to do the deeds; who knows great enthusiasms, the great devotions; who spends himself in a worthy cause; who at the best knows in the end the triumph of high achievement, and who at the worst, if he fails, at least fails while daring greatly, so that his place shall never be with those cold and timid souls who neither know victory nor defeat.” --Theodore Roosevelt
The Theodore Roosevelt quote is one of my favorites. Years ago I typeset it for the owner of Paragon. He framed it for his office wall. The quote applies to anyone who knows the joys and disappointments of the creative pursuits.
I hope you enjoy your weekend.
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 / firstname.lastname@example.org / www.paragonweb.com / www.facebook.com/paragonkilns
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