kiln crashing

[johnb]

Hi, I'm looking for either agreement with my solution or alteritives . I have a small Paragon kiln, cone 10. I only fire it to cone 6. I receintly fired it to 6 and when i open it I had alot of dunnting, cracking. I thought this was caused for a new glaze that I was trying out. The lost work was only testers so not so bad. I fired it again with another load and this time when the firing was finished I happened to turn out the lights and turned to look at the kiln and saw this orange band running around the room. I quickly adjusted a ramp/hold program for a slower cool down. Ok there is the breif history. I just finished another glaze firing and said to myself I need to fix this. I have some 1/8" fiber blanket which I thought that I could cut it to fit around the top of the walls and cement it in place with a refractory patching cement that I have. I will fire TO C 6 ONE MORE TIME AND THEN cement the top of the blanket. What do you think of this plan? John ( a new member)

[Mark C.]

I would not use cement and just place the gasket on top of bricks-Remember to wear a mask as fibers are not good to breath. This way when its worn out you can replace it easy-Gluing it is a bad idea for me-Every gasket I put on sooner or later needs to be replaced-Mine are all on the vertical plane on larger kilns .On your electric kiln gravity will hold it in place. I realize you want it on lid when raised but I would not glue it on there. I would maybe do a two piece and remove the front one for load ins and outs.

My 2 cents

Mark

[Lucille Oka]

How did the last two glaze firings turn out? Don't glue anything to your kiln.

 

The radiant light shouldn't have anything to do with the dunting you experienced. The radiant light is normal in sectional kilns. A small sectional can light up a room when fired to cone 6 the color is a bright orange yellow.

 

 

What was your firing schedule for that firing?

 

Kilns expand when they are firing. Over time the bands of the sectional kiln may need tightening.

 

 

 

Have you a Paragon manual for your kiln? Read the section on maintenance.

 

 

 

[johnb]

I would not use cement and just place the gasket on top of bricks-Remember to wear a mask as fibers are not good to breath. This way when its worn out you can replace it easy-Gluing it is a bad idea for me-Every gasket I put on sooner or later needs to be replaced-Mine are all on the vertical plane on larger kilns .On your electric kiln gravity will hold it in place. I realize you want it on lid when raised but I would not glue it on there. I would maybe do a two piece and remove the front one for load ins and outs.

My 2 cents

Mark

 

 

 

thanks Mark I kept thinking about it and yes I saw more cement and more cement and ect., you know I had a mouse problem so I got a cat!!!

 

 

Lucille, The next two firings went fine because I controled the cool down with my kiln master. I was hoping to find a way to seal the lid so I could cut the cost and retain the heat. This is an old, like me, kiln. I checked the fit when it was cold and it was tight. when I saw the orange-yellow it was 360 on the lid. I checked the band on the lid and it was tight. Thanks for your suggestion.

[neilestrick]

All lids lift a bit during firings. It's perfectly normal. It is not enough to make your pots dunt, otherwise it would happen in everyone's electric kilns. I think there's something else going on here. DO NOT cement anything to your kiln. The lid won't lift much, if at all, during the temps at which dunting occurs. If there's a gap when the kiln is cold, then you need to adjust the hinge or the wall bricks to tighten it up.

[OffCenter]

Probably the best solution for keeping the lid down is the most obvious one: put a little extra weight on the lid. Yes, I know electric kiln lids aren't meant to be table tops and you shouldn't put heavy things on them, but a kiln shelf spreads the weight out and put the shelf over the edge of the lid. Then put a brick or two on that. Will probably cut the gap in half at least.

 

Jim

[Guest JBaymore]

Another solution to the enlarging gap wih temperature increase is to vertically elongate the hinge pivot holes on which the lid pivots open by a small amount. This allows the expansion of the refractories in the back area (near the hinge) to not tend to lift the rest of the lid upward.

 

Requires a little surgery and the right tools to do it... but it is pertty simple to do.

 

best,

 

..............john

[neilestrick]

Another solution to the enlarging gap wih temperature increase is to vertically elongate the hinge pivot holes on which the lid pivots open by a small amount. This allows the expansion of the refractories in the back area (near the hinge) to not tend to lift the rest of the lid upward.

 

Requires a little surgery and the right tools to do it... but it is pertty simple to do.

 

best,

 

..............john

 

 

This is how L&L builds their hinges. It allows for even movement of the lid and saves some wear on the bricks near the hinge.

[Guest JBaymore]

This is how L&L builds their hinges. It allows for even movement of the lid and saves some wear on the bricks near the hinge.

 

Since it is such a basic concept on "how things work"...... it is crazy that all of the polygonal top-loader manufacturers don't do this "out of the box".

 

best,

 

..............john

[johnb]

Another solution to the enlarging gap wih temperature increase is to vertically elongate the hinge pivot holes on which the lid pivots open by a small amount. This allows the expansion of the refractories in the back area (near the hinge) to not tend to lift the rest of the lid upward.

 

Requires a little surgery and the right tools to do it... but it is pertty simple to do.

 

best,

 

..............john

 

 

Thanks John that was the first thing I did.

[yedrow]

I'm kind of curious as to how fast the temp is dropping and what size kiln you have.

 

Joel.

[johnb]

I'm kind of curious as to how fast the temp is dropping and what size kiln you have.

 

Joel.

 

 

It's a paragon 'High Fire' and it will go from 2165 to 1500 (app.) in 1 hour.

[cracked pot]

 

 

This is how L&L builds their hinges. It allows for even movement of the lid and saves some wear on the bricks near the hinge.

 

 

My L&L kiln has a metal latch that I use during firing that keeps the lid closed. The latch is not mentioned in the firing instructions so I hope I am doing the correct thing by latching it?

[yedrow]

I'm kind of curious as to how fast the temp is dropping and what size kiln you have.

 

Joel.

 

 

It's a paragon 'High Fire' and it will go from 2165 to 1500 (app.) in 1 hour.

 

 

That seems kinda fast to me. I have an older Amaco 10 cu. ft. kiln and it drops from 2220 to 1900 in about 50 minutes. That's about 420/hr. You are dropping something in the range of 1.5 times that. Personally, I wouldn't do the kaowool thing. Decompressing and re-compressing that stuff spooks me. Like everyone else I think you should look at your lid and maybe check the bottom. Have you talked to anyone about seeing how difficult it would be to repair the brick around the top of your kiln, assuming it has excessive wear?

 

If I remember right, you are okay dropping around 500/hr, but as per another thread, I believe (for the time being) that slowly dropping through the 1900 to 1500 range helps matt and floating glazes. So I don't think that is a good idea. However, someone more knowledgable could help with that rate of drop and dunting. I don't think you would get it, at least until somewhere near the critical temps.

 

 

Joel.

[Matt Oz]

As Neil mentioned the band of light is normal, here is an excerpt from a help article on the Paragon website

 

THE LIGHT AROUND THE KILN LID OR DOOR

 

Some people worry about the line of light that appears around a kiln lid (or door) at high temperatures. They wonder if the light means heat is escaping.

 

The kiln expands as it heats. The larger the kiln, the greater the overall expansion of parts. Since the hot inner surface of the lid expands more than the cooler outer surface, the lid or door bows slightly toward the firing chamber. This causes a small gap, where light from the firing chamber is visible. The gap is more pronounced on the ends of an oval lid than on a round lid.

 

But unless the lid rises during firing (the subject of another Kiln Pointer), there is little heat loss from the gap under the lid. At high temperatures, the molecules in air are so far apart that they no longer transfer heat through convection. This is why heat does not pour out of a peephole when you remove the plug.

 

On some models, we add a gap between the lid (or door) and kiln at the hinge. As the kiln gets hot, the gap closes due to the expansion of the firing chamber.

 

Full article http://www.paragonwe...ter.cfm?PID=386

[neilestrick]

 

 

This is how L&L builds their hinges. It allows for even movement of the lid and saves some wear on the bricks near the hinge.

 

 

My L&L kiln has a metal latch that I use during firing that keeps the lid closed. The latch is not mentioned in the firing instructions so I hope I am doing the correct thing by latching it?

 

 

Yep, go ahead and latch it.

[yedrow]

But unless the lid rises during firing (the subject of another Kiln Pointer), there is little heat loss from the gap under the lid. At high temperatures, the molecules in air are so far apart that they no longer transfer heat through convection. This is why heat does not pour out of a peephole when you remove the plug.

 

 

Wow, I never thought of that (and I'm going to have to think on it more). Now I'm wondering if it is a function of system size, so that in a larger space air would convect, but not out of a peep hole. Thanks!

 

Joel.

[cracked pot]

 

 

This is how L&L builds their hinges. It allows for even movement of the lid and saves some wear on the bricks near the hinge.

 

 

My L&L kiln has a metal latch that I use during firing that keeps the lid closed. The latch is not mentioned in the firing instructions so I hope I am doing the correct thing by latching it?

 

 

Yep, go ahead and latch it.

 

 

Neil,

 

 

Thanks so much. I have never seen the latch mentioned anywhere and started to think I was making a big mistake! Love my easy fire and don't want to inadvertently damage it.

 

Fran