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High Bridge Pottery

Building A Top Loader Kiln Lid.

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So.... My kiln is slowly being mended. I have the new elements being made up and some K26 bricks ordered.

 

The problem with the original lid was that it really has no support in the middle of the lid which then had a peep hole in the middle-ish brick causing structural issues. The lid was bricked up in the standard brick wall config (sorry I don't know the correct term) but I am wondering if there is a better way to lay the bricks. The old lid was in the end held together by the tension of the steel case round the bricks.

 

This was my idea from looking at pictures of kiln lids for the brick config.

post-23281-0-54944000-1403789139_thumb.jpg

 

I would have two stainless steel threaded bar going through and being bolted onto the steel casing (shown by the dotted line) This I hope will add enough support to the middle and with the peep hole being on the edge of two bricks instead of one it would negate the structural issues the old lid had with a hole in the middle of one brick.

 

Could I also pin the bricks to each other with small bits of element or would that make cementing the bricks straight too hard to get right?

 

Any advice on cementing the bricks as I have never done it before?

 

 

post-23281-0-54944000-1403789139_thumb.jpg

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David Hendley posted a design for making a round new lid using kiln cement and a steel belt. I think he may even have reused some of the original bricks from the old lid.

I think the steel rods may cause cracking across your new lid. Do a google for David Hendly's repair of a kiln lid. He had been a professional potter for decades and is a very resourceful guy for equipment and invention.

It was on Clayart a few years ago.

Marcia

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Why do you think the steel rods will cause cracking across the lid? I have been advised by a few people that this would be the best way to reinforce the structure. They also said to tongue and groove the bricks but I have decided against that.

 

I have found a few threads on David Hendley repairing his broken kiln lid but nothing on building a new one from scratch. Still, they were a good read and he did seem to pin his bricks together for extra support. It does mention coating the bottom of the lid with some facing coating but could I use kiln cement for this?

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The steel rod is totally unnecessary in a slab of that size, and will likely cause problems in a lid that's only 3" thick. The rod will be too close to the edge of the brick and will likely warp due to the heat. The hole in the middle of the old kiln had nothing to do with the failure of the lid. A crack may have found its way to the hole, but the hole itself is not a weak point. Mortared lids fail over time. It's just the nature of the beast. The flex and move a lot during a firing, and take a beating being raised and lowered every day. The best thing you can do to increase the life of the lid is to get a good quality hinge that mounts front and back on the slab, and all the way down the back side of the kiln. L&L and Skutt come to mind.

 

The key to good mortaring is to keep the mortar joint very thin, and get the bricks joined up quickly before the mortar dries. It's not as easy as you might think. Personally, I would spend the money on a factory lid, or find a cheap used kiln in the area and use that lid. If the floor slab is in decent shape then you'll have a backup. I would not spend the time and effort in making my own lid, knowing it will most likely not be as strong as a factory slab.

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Neil covered the mortar very well-if you make your own lid use a outer steel band like all commercial lids have-just design one. Forget the rods in such a thin brick.

Keep in mind the whole lid will expand  with heat thats why the band works so well.

Mark

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Thanks for the help :D

 

Ok, so no steel bars but some top notch brick work. This is going to be interesting as I have never really stuck two bricks together in my life. Better start reading up some more before I even try sticking them together. I am sure it will be the same as most things ceramics, easy once you know how to do it.

 

The hinge on the kiln is rubbish. Could it be a better idea to remove the lid when filling and store it on the top when not in use?

 

I have the steel from the old kiln lid to use for the new one. That was all keeping the old kiln lid together  :mellow:

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There has been a few threads on this topic-I recall watching a video link of the paragon factory guys making up lids on one of those threads in the past year or so.

You should find and watch that piece to see how its done on the commercial end.

Mark

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The rods are not needed and would cause problems as backed up by Neil and Mark. The bricks would not handle the expansion and contraction of the rod which would cause cracking in the thin soft brick.When mortaring, spray the face of the brick with water to slow the drying of the mortar.It will give you a little more time to get things fixed together.

Marcia

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Thanks for all the tips :) kiln bricks were delivered today so started sticking them together this afternoon. Decided to stick the lengths together and now waiting 24 hours for it to set up so I can stick the rest together.

 

These bricks seem to be thicker than what used to be there but only by a few mm. After the lid has been made I need to work on a counterweight pulley system.

 

Here are some photos anyway.

post-23281-0-82702700-1404147215_thumb.jpg

post-23281-0-48209800-1404147255_thumb.jpg

post-23281-0-31422100-1404147282_thumb.jpg

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It is an electric kiln. Not sure who built the kiln but I don't think the guy had much idea about anything. There is no space in the side for any peep holes because of how the elements have been installed. Just left with that one in the middle.

 

Bad idea?

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Oy! Heated air rises... and we thought the argument about proper eye protection for heat radiation was the big one.

 

Do you use a mirror on a stick to look through that peep?  Heated air in your eye aside, it seems like it'd be tough to look in that peep without leaning on a rather hot kiln.

 

Kudos on tackling rebuilding the lid yourself.

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You would be surprised how little heat comes out the top. At 1000 degC I can hold my hand a foot above the hole with no problems. I am quite a tall man so can lean over to see inside.

 

When firing glaze there is a bung that goes in. Pain in the butt to see cones so I have to wait till it is cool to find out what cone it made. No nice side view :(

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Well, it's a pain in the butt to see cones through a side peep hole.  The only way I can reliably do it is to set the cones so an element is behind them, and I can see them because of the contrast... but that means finding a clear view across the whole shelf.  But I fire manual to cone, so I have to see them.  Unfortunately, you don't even have that option with the top peep.

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Well, it's a pain in the butt to see cones through a side peep hole.  The only way I can reliably do it is to set the cones so an element is behind them, and I can see them because of the contrast... but that means finding a clear view across the whole shelf.  But I fire manual to cone, so I have to see them.  Unfortunately, you don't even have that option with the top peep.

 

I know you are not supposed to do this but what works for me is to paint a line down the cone with my black stain. It stands out very clearly when viewed. It might very slightly flux the cone but I haven't noticed any difference. Underglaze pencil works too.

 

One of my old kilns had very small peep holes, I rasped it out to a larger size which helped visiblilty also.

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Yes the 26 means 2600F. The spec from the company said up to 1400C operating temp. I did nearly go for 23's but thought it was a little close as I fire up to 1260C.

Another picture from today. The lengths of brick were a lot harder to push together than single bricks, also yesterdays bricks were not lined up exactly. Some were a mm or so off. Felt like I did a worse job today but hopefully in a few days I will be able to cut it into a circle. Looks a little rough but I am happy for my first go ever.
post-23281-0-97509000-1404246320_thumb.jpg

 

I would like to coat the lid with a protective coating. Could kiln cement be used for this? I feel like the answer is no but I don't know for sure.

post-23281-0-97509000-1404246320_thumb.jpg

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Flipped the lid today and filled in the gaps on the other side. Managed to add an extra cm to the width from being unable to push the bricks together enough. Hopefully all the joins will be ok.

Flipped it back over after a few hours and a bit of heat gun to start cutting. Got 3/4 of the way round with a jigsaw until the blade was very blunt. Have to go and buy another 2 at least to get the cut finished. Hardest part is going to be getting the circles to line up on each side.

 

Dust masks all round.
post-23281-0-60214100-1404319564_thumb.jpg

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Thank you John.

 

Yes I would like to get some sort of protective coating but I don't know what to use and have little money left. Not sure what they used in the video and I don't have their custom built curing box :(

 

Probably have to wait till next month when I get some more money.

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Hey, Paragon, and the other kiln/equipment companies too, have all the info you'll need, in most cases. It looks like they sell the kiln brick wash for lids on the paragon site. They also have a "pointers" section for the application.

 

http://www.paragonweb.com/kiln_pointer.cfm?PID=212

 

I'm sure the curing kiln is to handle their volume of production in a timely fashion.

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