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Preventing Glaze From Running On Pipes

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Guest JBaymore

 

 

Inorder to bring the shelves towards the door I will need to make some small cuts so it will fit into the doorway. Also the burners are right bellow the kiln and there are holes in the bottom 4 corners where the flame enters through 5inches of fire brick into the kiln.

 

 

OK... fires straight up. SO that is good with the spacing you have on the left and right sides.

 

Aha... so this (above) says that the CHAMBER is not as deep as what you were saying.  What I am now picturing is that the door closes against the outer face of the front wall..... and that front wall is 4 1/2" offset from the INSIDE wall of the actual chamber.  And when you gave the dimensions before you were including that space in the measurement.  Yes?

 

If you measure form the back wall corner (along the back wall) to the front wall corner (along the front wall)....... what is that dimension?  meaning the depth of the CHAMBER in the fireboxes on either side of the door opening.

 

And then what is the total depth of the shelves you are using?  Front edge of the shelf near the door end to the place it is touching the back wall.

 

We MAY be back to the idea that the shelves are too big for the chamber.... but not in one the sides.... but in depth.

 

That space left in the door area is not really helping things out as far as gas flow goes.

 

best,

 

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

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Right. But if James could stagger them so they went under the other side column like so, he could get them away from the from and back

 

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My updraft again has the 4 corner burners and two in front and back in-between the corners.

I leave space 3-4 inches in back and in front so flames go up and do not hit shelves directly much.

You can use different size shelves but allow the flame to go up about 1/3 of kiln height before flare hits shelves. You may have to cut some shelves down or use the shorter ones in lower 1/3. Just keep the posts lined up as you stack up the load.Hope thats clear 

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So James, 

Take a good look at your kiln and think about the way the flame has to be directed through the ware and shelves. Think about it really hard and you'll come up with a solution. You have been given lots to think about.

Marcia

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Guest JBaymore

Right. But if James could stagger them so they went under the other side column like so, he could get them away from the from and back

 

_______

[]     _[]_____[]_

[]____[]_       []

[]     _[]_____[]_

[]       []         []

 

 

Yup.... except unlike most of us... he just makes pipes... so there are no taller pieces to fill into the higher shelf areas because of the stagger.  Smaller shelves spaced in there could fix that.

 

best,

 

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

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Inorder to bring the shelves towards the door I will need to make some small cuts so it will fit into the doorway. Also the burners are right bellow the kiln and there are holes in the bottom 4 corners where the flame enters through 5inches of fire brick into the kiln.

 

 

OK... fires straight up. SO that is good with the spacing you have on the left and right sides.

 

Aha... so this (above) says that the CHAMBER is not as deep as what you were saying.  What I am now picturing is that the door closes against the outer face of the front wall..... and that front wall is 4 1/2" offset from the INSIDE wall of the actual chamber.  And when you gave the dimensions before you were including that space in the measurement.  Yes?

 

If you measure form the back wall corner (along the back wall) to the front wall corner (along the front wall)....... what is that dimension?  meaning the depth of the CHAMBER in the fireboxes on either side of the door opening.

 

And then what is the total depth of the shelves you are using?  Front edge of the shelf near the door end to the place it is touching the back wall.

 

We MAY be back to the idea that the shelves are too big for the chamber.... but not in one the sides.... but in depth.

 

That space left in the door area is not really helping things out as far as gas flow goes.

 

best,

 

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

 

Yes the measurement was including that 4.5 inch space from the inside of the wall to the outer part of the wall where the door shuts. The space in the kiln from back wall to inner front wall is 18.5inches and the shelves are also 18.5 inches, I squeeze them in there tight. As far as that space in the door goes I was thinking of trimming the shelves so that they would fit in the doorway and then I could execute that spacing you mentioned.

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Guest JBaymore

James,

 

OK thanks for the dimensions.

 

TYPICALLY, on an updraft you would want at least an inch between the edge of the rear shelf (of the two shelves) and the back wall, an inch between the back shelf and the front shelf edges, and an inch between the front edge of the front shelf and the front wall (assuming that the door "filled in" the wall section where it closed so that the chamber was basically a cube).  Preferably have more than that.

 

That space "inside the door seal area" does buy you some potential place for flames and hot gasses to pass upwards around the stacking of shelves. But this is true only if you manage to keep the front edge of the front shelves near the bottom and near the top from "sealing off" the flame path from the bottom floor area to the top of the arch where the exit flues are.  So stacking arrangements will be critical if you continue to depend on this space for flow of combustion products. You want to "encourage" some of the flame from the front pair of burners to want to travel up along this space and travel toward the exit flues.

 

If that were a true 18" deep "cube" kiln with a door that almost completely "filled in" the opening into that chamber, I'd be designing it likely using a single 14" deep by X" wide shelf (in the picture looks like maybe a 22" or 24").  That would put 2" of space around the shelf front and back.  Or preferably two shelves that were 14" deep, and X" each wide to make up the necessary width available, still leaving the space of the fireboxes on either side.  Stacked with an inch between them.

 

Yes some of the changes will result in "less stacking space"......if that is ALL you look at.  BUT......... fixing the even-ness of firing will increase the percentage of firsts that you get out of each firing. So it will SEEM like a bigger stacking space kiln.

 

NOTE:  The more detailed pictures you can get on your gallery of this kiln, the better any of us can maybe help with suggestions.  AND.... get that detailed firing procedure / schedule up here so that we can maybe make suggestions there also.

 

best,

 

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

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Guest JBaymore

Maybe James should expand his product line to include bongs to fill in the taller spaces. :rolleyes:

Marcia

 

I'm not going there......... ;)

 

best,

 

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

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Guest JBaymore

What size are the individual shelves? 

 

He said 2 of them make up 18.5" in the above post. (Odd size.) So that gives the one dimension.

 

best,

 

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

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James,

 

OK thanks for the dimensions.

 

TYPICALLY, on an updraft you would want at least an inch between the edge of the rear shelf (of the two shelves) and the back wall, an inch between the back shelf and the front shelf edges, and an inch between the front edge of the front shelf and the front wall (assuming that the door "filled in" the wall section where it closed so that the chamber was basically a cube).  Preferably have more than that.

 

That space "inside the door seal area" does buy you some potential place for flames and hot gasses to pass upwards around the stacking of shelves. But this is true only if you manage to keep the front edge of the front shelves near the bottom and near the top from "sealing off" the flame path from the bottom floor area to the top of the arch where the exit flues are.  So stacking arrangements will be critical if you continue to depend on this space for flow of combustion products. You want to "encourage" some of the flame from the front pair of burners to want to travel up along this space and travel toward the exit flues.

 

If that were a true 18" deep "cube" kiln with a door that almost completely "filled in" the opening into that chamber, I'd be designing it likely using a single 14" deep by X" wide shelf (in the picture looks like maybe a 22" or 24").  That would put 2" of space around the shelf front and back.  Or preferably two shelves that were 14" deep, and X" each wide to make up the necessary width available, still leaving the space of the fireboxes on either side.  Stacked with an inch between them.

 

Yes some of the changes will result in "less stacking space"......if that is ALL you look at.  BUT......... fixing the even-ness of firing will increase the percentage of firsts that you get out of each firing. So it will SEEM like a bigger stacking space kiln.

 

NOTE:  The more detailed pictures you can get on your gallery of this kiln, the better any of us can maybe help with suggestions.  AND.... get that detailed firing procedure / schedule up here so that we can maybe make suggestions there also.

 

best,

 

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

Yes I forgot to add the schedule and as far as pictures go, I have a video you can watch and have a better understanding of my kiln. The point you will want to watch is at 9 minutes and 20 seconds. (

).

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Maybe James should expand his product line to include bongs to fill in the taller spaces. :rolleyes:

Marcia

 

I'm not going there......... ;)

 

best,

 

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

 

So I am going to write the schedule for three different firings. The first two schedules had a similar set up with an octagonal shelf at the top and was 4" inches away from the flue. The video link I posted one time back was the third schedule.

 

#1

11:45 On: Gas 1/4 open. Flues 1/3 dampened.

2:45: turn gas to 1/2 open.

5:45 turn gas to 3/4 open. Flues 1/2 dampened now.

8:45: turn up full open. Slightly open damper until smaller flame.

11:15 Off

 

#2

9:26: gas open 1/4 damper 1/3

12:42 gas open 1/2 damper 1/2

3:40: gas open 3/4

5:35 full open 

8:00: open damper to reduce flame

10:35 cone 10 hit on top

11:05: Off

 

#3

4:50 gas open 1/4 damper 3/4

8:20 Turn up 1/2 & damper 1/2

11:30 Turn up just under 3/4

1:30 Turn up just bellow full leave until done

2:50 Close damper 3/5 back side

7:00 cone 6 starting to hit was going into 7 Cone 10 hit Turn OFf

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Natural gas or propane? Is there a pressure gauge on your gas line? If so, what's the max pressure you're firing at?

 

Can you expand on the firing schedules at all? Like at each of those times, what's the temperature? That would give us a better idea of how fast or slow it's heating.

 

Just based on what you have here, I'd say your damper is too far open and you're using too much gas.

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Guest JBaymore

Yes I forgot to add the schedule and as far as pictures go, I have a video you can watch and have a better understanding of my kiln. The point you will want to watch is at 9 minutes and 20 seconds. (https://www.youtube.com/watch?v=9SgFYNCBBAo).

 

JUST when I thought we were going to see the actual firing conditions....... you cut to unloading.  Oh well.

 

Just looking at the load part........ you need more space around the shelves in the front and back (and in between a pair) for sure.

 

If you can, get us some more detail like Neil is asking bout.  And if you can shoot some footage of FIRING...... please do.  Shoot some at different points in the firing.  Take some shots showing the exit flues, the spy ports, and under the kiln showing the burner area.

 

best,

 

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

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 When they moved the ceramics department to a different building I heard they just bricked up the doorway to the little room it lived in.

 

With it still in there?  :wacko:

 

best,

 

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

 

 

Yes! It would have been a major ordeal to get it out.

 

 

 

Ha!  That will be a fun discovery sometime in the future!  My coworker at one of the Elementary buildings discovered an electric kiln in the basement of one of the buildings he travels to.  No one remembered it was there, as it hadn't been used in decades.  So when he started there, he had no idea that he had a functioning kiln at that building.  That kiln was sitting in plain sight and it was forgotten about.  I can only imagine the surprise that people will have at your old school if and when that bricked up area ever gets opened back up.

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Yes I forgot to add the schedule and as far as pictures go, I have a video you can watch and have a better understanding of my kiln. The point you will want to watch is at 9 minutes and 20 seconds. (https://www.youtube.com/watch?v=9SgFYNCBBAo).

 

JUST when I thought we were going to see the actual firing conditions....... you cut to unloading.  Oh well.

 

Just looking at the load part........ you need more space around the shelves in the front and back (and in between a pair) for sure.

 

If you can, get us some more detail like Neil is asking bout.  And if you can shoot some footage of FIRING...... please do.  Shoot some at different points in the firing.  Take some shots showing the exit flues, the spy ports, and under the kiln showing the burner area.

 

best,

 

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

 

Well that will have to be a video for another day...

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Natural gas or propane? Is there a pressure gauge on your gas line? If so, what's the max pressure you're firing at?

 

Can you expand on the firing schedules at all? Like at each of those times, what's the temperature? That would give us a better idea of how fast or slow it's heating.

 

Just based on what you have here, I'd say your damper is too far open and you're using too much gas.

It is a natural gas kiln with no gauge (it is a 10ft 1inch line that goes into a 1/2inch line under the kiln before it reaches the burners). As for the firing schedules that is all I have, my pyrometer stopped working so I decided to just use cones. But I do have one more schedule from when the pyrometer did work.

 

Schedule: ( the first shelf was off the bottom of the kiln by 14inches though(9.5 inches higher from the other firings), had to fit some water pipes)

10:22 Start low gas damper 3/4

11:36 Turn up 1/4 dapmen 2/5 (500F)

1:30 open flue 1/2 turn up to 1/2 open (1333F)

3:30 3/4 open (1942F)

5:30 full open (2173F)

6:23 End kiln sitter dropped and large cone (2232F)

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My few points are-

that you need more space around the shelves for combustion. 

slow the fire down near the end-push the damper in more so flame is just starting at bottom spy plug

buy a cheap digital pyrometer (THEY ARE CHEAP)and still use cones-that way you know about small temp changes

You can get more pipes into that load-they can be much closer than the space you have between them now.

also it looks like you are using soft brick for posts near the top of kiln-if this is true go buy some real stilts as that brick is not made for this.

If the stilts are cut from hard brick you are fine.
also just use 3 stilts per shelve so 6 total you are using 7 for some reason? this will also give you more space.Its best practice to use a 3 point stand on shelves . that is 3 stilts-two on the long corners and one in the middle on outside edge .

since this kiln is fiber it will climb very fast and cool fast so slow it down when the glaze is melting to even it out.

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My few point are

that you need more space around the shelves for combustion. 

slow the fire down near the end-push the damper in more so flame is just starting at bottom spy plug

buy a cheap digital pyrometer (THEY ARE CHEAP)and still use cones-that way you know about small temp changes

You can get more pipes into that load-they can be much closer than the space you have between them now.

also it looks like you are using soft brick for posts near the top of kiln-if this is true go buy some real stilts as that brick is not made for this.

If the stilts are cut from hard brick you are fine.

also just use 3 stilts per shelve so 6 total you are using 7 for some reason? this will also give you more space.

since this kiln is fiber it will climb very fast and cool fast so slow it down when the glaze is melting to even it out.

Great information, I know I can make it work much better now with all of this. Thank you so much

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Keep and log. Gas pressure adjustments are key. On that big olsen kiln thee were 4 columns of 18 x 18 shelves 1" thick. That was a pain. As we have all said, more space around all side and in between, stagger where you can. I would gradually damper down not up as you go after a body reduction at 09 -04....1/2 down to 1/4 maybe more when glaze reduction happens.

Marcia

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Well once again thank you all so much for your help, I know this will really change things for me. And of course if you ever need a ceramic pipe you know where to go.. haha Cheers everyone

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