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Joseph Fireborn

Curious Question About Heat Rate Near Cone 6 - Slower Rate - Glaze Improvement?

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So I was thinking about glazes and I fire my kiln at 108F/h to cone 5 and hold for 60 minutes. This got me thinking about trying orton's other rate of climb. Trying something like 27F per hour to cone 6 instead of using a hold at cone 5. So fire to 2111F, 1965F then climb to 2165F at 27F/per hour. I was wondering if anyone has tried this type of schedule? I am curious at the differences it would make in my glazes. Instead of going straight cone 6, changing to cone 5 with an hour hold improved my glazes a lot. It got me thinking about trying this. 

 

Anyone fire at that final rate of 27F/h? Did it improve your glazes or no change? 

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don't know the Centigrade conversion this early but from 1100C I climb 80C to the top then hold for 15. I find this lets the glazes settle and smooth out so that the longer hold is not necessary but you are going to C5 then allowing the hold to mature your glazes, sorry just a babble here this am.

Your glazes you have posted previously look great Joseph, what is it you are after in this research?

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Your glazes you have posted previously look great Joseph, what is it you are after in this research?

 

Thanks! I don't know exactly. I drive my wife crazy with all this. She doesn't understand why I just can't be happy with my schedule. I feel like there's always room to improve. One of the reasons I want a test kiln so bad so I can try out schedules constantly until I get one that I can't live without. 

 

I guess I just saw a big improvement in using a hold to reach top temp. My glossy glazes are much smoother and brighter. It also seems to make my reactive glazes more interesting. So I just got me thinking what is another way of slowly reaching cone 6. So I was thinking about this from that perspective. I am probably just going to leave it for now. I have so much work to glaze. I have one of those huge deep 4 stacking shelves full of bisqued work that I need to glaze and get listed. That is why I posted the question instead of just trying it. I was hoping someone tried it, but I have never seen a schedule that list that type of firing for electric. But I have read that large gas and wood kilns are slow to reach final temps, so it peaked my interest. 

 

I am sort of on a deadline to get work up before the Christmas season starts rolling in. Usually around October my friend says his stuff starts flying off the interenet shelves. I would like to have 200-400 items listed by then. So I got to get my butt in gear. 

 

Another part of me just likes discussing schedules and glazes.  :ph34r:

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With a 60 minute hold at cone 5, you are likely getting to a heat work equivalent of cone 7. Are you planning to keep the same hold at cone 6 or shorten it? I'm not sure slowing down to climb will make that much difference because of your hold -- the hold is likely more responsible for the nice melt you are enjoying. Before messing with climb rate, maybe try your current schedule to cone 6 and reduce the hold to 30 minutes and see the results. A test kiln with controller would be ideal for this, rather than a full kiln load.

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So I was thinking about glazes and I fire my kiln at 108F/h to cone 5 and hold for 60 minutes. This got me thinking about trying orton's other rate of climb. Trying something like 27F per hour to cone 6 instead of using a hold at cone 5. So fire to 2111F, then climb to 2165F at 27F/per hour. I was wondering if anyone has tried this type of schedule? I am curious at the differences it would make in my glazes. Instead of going straight cone 6, changing to cone 5 with an hour hold improved my glazes a lot. It got me thinking about trying this. 

 

Anyone fire at that final rate of 27F/h? Did it improve your glazes or no change? 

A slower firing will give you improved results.  You should fire to 1965 deg F than change ramp to 27 deg F and fire to 2165 deg F, and use self supporting cones.  The cone tables are based on the last 200 deg F of firing.  You can also use different rates for the last 200 deg F, example 60 deg ramp to 2205 deg F starting at 2005 deg F.  Depending on how good your thermocouple is you should come close to cone 6 down.  You can also change how fast you get to the 200 deg F before changing the final ramp to temperature so that it will not take such a long total time to fire the kiln.

David

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@Bruce, I have confirmed a perfect cone 6 on all levels of the kiln. I do a stagger stack and put in cones: 5.5 6 and 7 and 5.5 is touching with a slight melt of the tip, 6 is perfect bend and 7 is slightly bent. I agree that the hold is what is making my glazes look so much better than before. I was just curios if the slower heat would be a better result than the hold, if no one has tried it then I will wait till I get my test kiln because I am at the point where I am happy enough with my glazes. I will attach my favorite tiles below.

 

@David, I had a brain fart when I posted those above numbers. I dunno what I was thinking you are right that it needs to be 200F worth of firing for the cone to bend properly at the orton chart temps. Glad you caught that cause I would have totally ran that schedule eventually. I will edit my post to correct that.

 

--

 

These are my favorite glazes at the moment. As you notice the tile looks different on the right hand side. I dip these tiles then I spray a modifier glaze over the top on the middle lightly then heavily on the edge. This allows me to see what my modifier does. Sometimes its good and sometimes it is terrible. Either way it makes the glazes change is beautiful ways.

 

post-63346-0-95200500-1463280113_thumb.png

 

For larger images: http://s1183.photobucket.com/user/josephrosenblatt/library/Test%20Tiles

 

I don't know if changing my schedule will push these any further but I keep trying. These have been a lot of testing over the last few months to get these looking as good as they do. They are some of my favorite glazes to date.

 

When I get my test kiln this year I plan on spamming 7x5 currie grid tiles all day long.

post-63346-0-95200500-1463280113_thumb.png

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@jpdes sure:

 

I just started testing variations of glazes with titanium dioxide(Ray also does this) until I found a sweet spot that worked with my firing schedule. On a normal cone 6 firing schedule it doesn't do anything that well at all. 

 

I tried using Strontium Crystal Magic, but I felt it matted my glazes way to quickly and the ones it didn't it ran all over the shelves. So I just started testing different glazes with titanium in it to get a feel for their effects then I took some base glazes like the 20x5 added 10% titanium and started throwing in other ingredients like small amounts of lithium and iron. Eventually I came to a modifier glaze. To be honest any glaze on top of another can do really wild things.

 

What cone are you firing to and what does your schedule look like? Cause if you just fire straight to cone 6 with out slow cools and holds on the way down it wont change much at all. Also these glazes were changed slightly along the way to react(melt better) with this modifier, the regular glazes I use with the modifier over it do hardly anything except make the glaze look worse.

 

When I first read this article: https://digitalfire.com/4sight/material/titanium_dioxide_1644.html I saw that titanium could be used for a modifier, of course in their pictures it isn't nearly as drastic as the effects of mine. But you have to remember those glazes are very drastic already. I have attached some regular glazes to show the effect of the same modifier on glazes that are not highly reactive.

 

So my advice really is to start testing titanium based glazes on top of your current set of glazes, look at their ingredients and sort of find glazes that you have that are very interesting then brush or spray it on top of some of them and see what happens. It is a lot of work, but knowing what is happening and why it is happening is a lot better than a random recipe. I should take a picture of my garage and show you the 300+ containers of 100-200ML test batches I have. (one of the main reasons I am switching to currie method so i can find better glazes quicker then test vertical. so much wasted ingredients.) 

post-63346-0-52057600-1463283430_thumb.jpg

post-63346-0-52057600-1463283430_thumb.jpg

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The last part of my schedule is

1100 to 1220°C has a ramp rate of 80°C/hr with a 5 minute hold I believe. Yields a ∆6+

Then the cooling is controlled at 120°C/hr to 940°C and held 45 minutes.

 

--

What I have seen is small changes to the firing schedule does change the results. I personally prefer the sharper peak and reaching a higher temperature. I feel this program has given me more vibrant colors and excellent glaze interactions with a durable, glossy finish. So I stopped tinkering with it for a little while.

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Hey everyone.... Completely clueless but wanting to tweak my firing and have been reading all the lines on firing schedules to educate myself. You guys are fearless with your firing let me tell you!

 

I see some are doing a cone 5 with a long hold to get to cone 6 with good results. I was wondering why you don't do a cone 6 firing then program in a hold at a slightly lower temperature to get the results desired. Does this change the results? I think this schedule might fall under a controlled cool?

 

Now that I have my test kiln I want to play some with firing schedules since I don't have to risk a whole kiln load while learning.

 

Results I am interested in getting.... Less pinholing on certain glazes, improved vibrancy in colors and more of an interesting reaction between layered glazes for some as well. From what I have read this is all possible with firing schedules and I am just trying to figure out where to start.

 

T

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@ Pugaboo: If you could post your current schedule here we could give some advice on modifying it. But really it all is dependent on the type of glazes your trying to achieve. I use matte and glossy glazes in the same firing schedule, so I have a lot of holds and slow cooling, but not so much slow cooling that my glossy glazes are effected by it. For example I slow cool from 1900F by 200F/h until 1500F. So it isn't a really slow cool, but it is just enough where I do develop some crystals, and my mattes become nice and soft to touch. I also have several holds after the top temperature for 30 minutes to make sure my glazes get plenty of time to heal and it also gives my more reactive glazes time to run and develop more interesting surfaces instead of freezing them in place by dropping super quickly after hitting cone 6. My kiln will drop from cone 6 to like 1700 degrees in a very fast time. This causes so many defects on my pots that I had to add in holds and slow it down on the way.

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I use the Bartlett Cone Fire Slow Glaze Setting. The chart I found only shows the schedule for cone 04, I am assuming it's about the same for cone 6 just for longer periods to get higher temps. Might be wrong as I said I am clueless but want to learn. I know the last 200 degrees is important for the orton self supporting cones I use to do their thing showing the heat work. The cone fire Slow Glaze is what I have always used, the teacher I had said there was really no need to use the other settings in the controller. I want to be able to fine tune my firing though so I need to know just what it's doing under its Slow Glaze setting. I am hoping you all here can help me educate myself.

I THINK the Slow Glaze setting is:

150F an hour until 250F

Then

400F until 1695F

Then

120F until 1945 final temp of cone 04

 

At the moment I am wanting to try 1 thing to start:

1) fire to reduce pinholes, smooth out the glaze and get additional glaze movement on the surface. I think this means I either need to fire to cone 5 with a hold of some unknown amount. OR fire to cone 6 and program in a slow cool dropping a certain number of degrees and holding that temp a certain amount of time to help the glazes flow and smooth a bit longer without adding additional heat work.

 

As I said educate me! Seriously it's sad I haven't learned this part of being a potter yet. Around here everybody I ask just says use the slow glaze program. Or I get I fire to a cone less and then hold X number of minutes to get what I want and it's never the same amount of hold minutes.

 

I look forward to learning more with your help.

T

PS. Would that book on Electric Kilns answer some of my questions or does it not cover the Bartlett Comtoller?

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Pugaboo. The first change I would make is to take the glazes that are pinholing run your slow glaze schedule, then after you reach top temp cone 6, instead of shutting it off drop 100F and hold for like 20-30 minutes. See if this helps that glaze.

 

That would be the first change. Remember when you are testing, change only one thing at a time.

 

I don't know exactly how to add a down ramp on your controller but I think if it is like mine that you can still use the slow glaze schedule and then attach a custom down ramp to it. Look it up in your manual.

 

I am sure others who know more about this might help. If you can't do that email your kiln maker find out the schedule and just program it custom.

 

I know the l&l manual you have for your test kiln has the directions in it to add a down ramp addition.

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Hi Pugaboo, you're right that the 'Slow Glaze' setting uses those ramps. With the V6-CF controller there's a great option called 'Vary Fire', where you can program your own ramps and still use the Cone Table to determine your final temperature. This allows you to program in holds and cooling ramps as well. Here's how I programmed it on my test kiln:

 

-Press 'Enter Program' and then '5' when asked how many ramps (I use the same ramps as the 'Slow Glaze' program for the ramps in the climb up)

Ramp 1: 150/hr to 250F

Ramp 2: 400/hr to 1920

Ramp 3: 120/hr to Cone 5--instead of putting in a temp in this ramp, after entering the rate (120), hit 'Cone Table' and then '5' when it asks which cone

15 minute hold (each ramp has the option of adding a hold, I only add one at the top temp, be sure to enter 0015 instead of 1500 or you'll hold for 15 hours ;)

My last two ramps are for slowing down the cooling to try and replicate results that a larger kiln might, but not for any special effect--

Ramp 4: 420/hr to 1900

Ramp 5: 320 hr to 1400

 

The instructions for using the 'Vary Fire' with the cone table is on page 12 of the user manual which is available online here

Hope I didn't confuse you further, it's a bit of a learning curve but worth it to play around with your own programs :)

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Thank you Joseph and Nancy!

 

I will read the manual again and then go play with the buttons and familiarize myself with the settings I have not used before. Now that I know I was reading the schedule correctly I feel a bit more confident in changing it to meet my needs.

 

Learning this will also help me duplicate the results In my test kiln as well so that's a bonus.

 

T

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Learning this will also help me duplicate the results In my test kiln as well so that's a bonus.

 

Yea if your going to have the same results in your test kiln as your big kiln your going to have to come up with some sort of cooling schedule so that they cool at the same rates. It can be something as easy as 200F an hour until 1500F. 

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Joseph I don't have a programmable kiln I just work with a dual pyrometer set up.  I have found that if I fire it to C5 and then slow the firing to C6 I get the glaze firings I am happy with and no down firing.   Denice

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Joseph I don't have a programmable kiln I just work with a dual pyrometer set up.  I have found that if I fire it to C5 and then slow the firing to C6 I get the glaze firings I am happy with and no down firing.   Denice

 

I might have been misunderstood here. I am not saying you have to slow cool to get good results. I am just saying they helped my glazes drastically look better and more interesting. And thanks for the information on slowing down the firing to cone 6, how slow do you go? 

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Hey everyone.... Completely clueless but wanting to tweak my firing and have been reading all the lines on firing schedules to educate myself. You guys are fearless with your firing let me tell you!

 

I see some are doing a cone 5 with a long hold to get to cone 6 with good results. I was wondering why you don't do a cone 6 firing then program in a hold at a slightly lower temperature to get the results desired. Does this change the results? I think this schedule might fall under a controlled cool?

 

Now that I have my test kiln I want to play some with firing schedules since I don't have to risk a whole kiln load while learning.

 

Results I am interested in getting.... Less pinholing on certain glazes, improved vibrancy in colors and more of an interesting reaction between layered glazes for some as well. From what I have read this is all possible with firing schedules and I am just trying to figure out where to start.

 

T

You can use a hold at cone 6 but you have to change the top temperature to keep a cone 6 firing .  For example cone 6 at 108  F ramp equals 2230 F, no hold, but a 30 minute hold means you need to change the top temperature by -40 = 2190 F to get the cone 6 to stay about the same.

David

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If you ramp at 27F/hr for the last 200 degrees, that's about 8 hours for the last 200 degrees. Your electric bill will go way up and your element life if going to go way down with that type of firing schedule. I have a customer who does something like that and she gets less than 100 firings from her elements instead of the usual 150. What you're accomplishing by holding at the end is simply spending more time at the high end of the firing when the glazes are molten, which gives them more chance to flow. I would expect you can accomplish the same thing with a ramp of 108F/hr or even faster (180F/hr), up to or at least close to cone 6, plus a short hold. Basically, firing faster but hotter may accomplish the same thing. If you also slow down the cooling from the peak temp, the'll spend a little more time in that molten range. I cool from cone 6 to 1550 at 175F/hr and my glazes definitely flow more than when I don't control the cooling.

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@Neil, I didn't even think about element life. I will stick with what I am doing.

I have never used the 27 F ramp, because of the time it takes.  I do use sometimes the 60  F , and the 80 F ramp and make my own program to keep the overall time around 7  hours.

David

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