Reading Cones

[Mark C.]

This was brought up a week ago so I thought I would add some info.

These cones  I show will apply to whatever temp range you are working with-as the position of cone is key whatever range your in. It will not matter if its cone 06-cone 6 or cone 11-the bend in whatever

Now first let me say that you should have 3 cones in your pack not the two that I show

This will tell you more info-I use two only because of my specific needs and experience.

Also these are for the large cones only-small ones are not made for this visual use.I make my own cone packs from scrap porcelain clay

Never use wet clay as they can blow up and you need cones to really know whats going on in a kiln and cones are the best refreence you have-no matter how you like your digital controller and trust it.

Lets say you are firing  to cone 6-that means you will need a cone 5 a cone 6 and a cone 7 in your pack.

I premake mine weeks before needed so thay are dry.I make 8-10 pads at a time

Make your packs so the cones do not fall onto each other they need to fall free and away from each other-that way you can read them in the spy hole.If you cannot see them but a small brick behind them which makes it easier -also use the right eye proctection when viewing cones in kilns as you can damage your eyes without the right glass.-You can look this up as this thread is about reading cones not the glass to use.

Now cones can fall all at once or separately or in between thats just the way it is. Whats important is the cone you are firing to.

There is some good info here so its worth your time reading

 http://digitalfire.c..._cones_193.html

As you can see using a clock face is good way to talk about where a cone is-3 oclock is 1/2 way down

1 oclock is a soft tip etc.

When I fire I'm usually going to what I refer to as a soft cone 11 that is to say I want that cone to read between 1:30 and 3 oclock (this is in referance to a clock face or if you read the link above you will understand this now and what it means as to temps)

I choose this time depending on how long my fire is going. Fast fire vs slow fire.There is a time temperature relationship.Many call this heat work-heat work is something you should master and cones can help.

Glazes will melt more if you fire them longer than if they are fast fired with same cone bend . A 12 hour fire say vs a 7 hour fire. Or at least that is my experience in my gas kilns.

So if the fire is long I choose a softer less bent cone .I hope this is cear.

 

So in the groups of cones in second Photo-they are

Group A is cone 10 end point soft cone 11-that means cone 11 is 1:30 to 3 oclock-this is what I fire to usually

Group B end point cone 11the tip is equal to the base-this is what I fire to in a fast fire

Group C whoops its way past cone 11 and got away from me.All cones (10-11) are flat-this is what happens when the phone rings or friends are visiting while glaze firing.

 

In the first photo it the dilemma what to do with your cones???

I pile them up and every year toss them out

Mark

[jolieo]

Thank you for taking the time Mark . I really appreciate it . I was going to buy a controller . My kiln does not have a sitter. Then I read that some of you don't use either. Money is tight, but more importantly, I think that I need to spend time reading the heat. One question, if cones are self supporting, why a pack,.? Can't I just leave them standing? Or are those just large cones , not self supporting? And then which should I buy? Xox thanks ! Jolie

[Mark C.]

These are not self supporting-I do not use them.I buy the box of 50 large regular cones . They are very stable in clay pads and you can put them close together and get then on a angle view if the spy ply is small.For me setting up each cone would be a pain in the neck for 3 seperate ones

I have always made my own cone packs.

I prefer my own pads.I suggest learning to make your own pads-there was an arcticle in CM or thier sister publication ? recently on this

mark

[Judith B]

Really interesting, thank you for sharing!

I was wondering what is the point of using cones when you have a temperature controller inside the kiln? In an electric kiln, it would just shut off when the temperature has been reached but I know some people still use cones and I don't understand why?

I know it's a beginner question but I have never used cones before!

[Mark C.]

The reason to use cones is to know what really is happening (in my case I have a manual gas kiln)

If you just use your controller and the glaze is underfired you will not know what temp it acually got to (time and temp realationship I spoke about)

Yes you have a digital readout but thats a static number not the time temp of the actual cone. So its more info for you to know (more info is a good thing)

Now as you know the digital controller works on the thermocouple which wear out over time and give false readings which means sooner or later a under or overfired load of pots. The cones tell you what is happing as well as what happened.

If you only use your controller then you should at least put a few cones in to see what is happening in all the kilns areas nit just where the thermocouple is.

What I'm saying is its not just a static temperature reading its a time temp deal-the digital controller with ramp rate etc. work on this heat work factor-cones show heat work in real time.

Most thermocouples show a temp which especially at cone 9 and above is far fron the truth of what it really is-then cones are what is needed-I cannot say this for cone sixarea  as I do not work that range in my pottery work-Mine is cone 10-11 gas work.

I can say that if you trust your controller only he day will come when it craps out via the thermocouple and without a cone to tell you what is happening that load of pots will not be up to speed either to hot or to cool but not right.

Cones tell you what is happening when its happing and afterwards what happened.Pretty great thing for such a low cost .$30 dollars for 3 boxes of 50 each-thats 50 fires.

Mark 

[Chilly]

The way I think about "heat/work" is to compare it with cooking.

 

You wouldn't put a large fruit cake in the oven and take it out as soon as the oven got to the correct temperature.  You need to leave it in until it's properly cooked.  Even a domestic oven doesn't always heat to the same temperature, so we use a skewer and poke it in the cake to see if it's cooked.  The same applies to pottery, except we don't open the kiln and poke at the pots.

 

Cooking or firing both need a combination of time and temperature.  

 

You can get the same work at a lower temperature for a longer time, but as Mark C keeps saying above, the only way to know (really really KNOW) is to use cones.  Thermocouples/controllers deteriorate.  Cones always work.

[High Bridge Pottery]

Really interesting, thank you for sharing!

I was wondering what is the point of using cones when you have a temperature controller inside the kiln? In an electric kiln, it would just shut off when the temperature has been reached but I know some people still use cones and I don't understand why?

I know it's a beginner question but I have never used cones before!

 

In theory you reach a temperature and all your work is perfectly fired. Never does that in reality, cones help you diagnose issues. If you do it long enough I am sure cones can be used to check the thermocouple readings every now and again and you can have perfect firings. I have been trying for two years and mine are still neither here nor there. Maybe it's because I keep fiddling with the firing

[David Woodin]

As everyone has said cones show heat work, thermocouples read temperature at its tip, but you can corelate all this information and get good firings with controllers. The ceramic Industry uses controllers but always have cones in each firing.  Self supporting cones are very accurate but cost more.  Large cones are only as accurate as how they are set in the cone packs, so read what it says about setting cones on the Orton box.  The base of the cone is cut to the correct 8 deg angle.

David

[rayaldridge]

I find that the best way to set cones in a cone pack is to press the base of the cone to a flat surface, so that the cone takes up the precise angle it was designed for.  Then move it to the clay pat and press it in, keeping the angle the same.

[David Woodin]

I find that the best way to set cones in a cone pack is to press the base of the cone to a flat surface, so that the cone takes up the precise angle it was designed for.  Then move it to the clay pat and press it in, keeping the angle the same.

That is fine for the angle but the height is also critical.  The box doesn't tell you the height but the Cone table says if 1 3/4" use self supporting table, if 2" use the large cones table.

David

[rayaldridge]

David, I might not be understanding what you mean.

 

If you press the cone into the clay pat so that the cone's bottom is at the bottom of the pat, how would the height vary to any significant degree?

 

If you do it the same way each time, your results should be consistent.  I guess what I'm saying here is that if in my kiln Cone 8 is down and I like the way my glazes look post firing, all I'm looking for next time is to have Cone 8 (from the same box) go down to an identical extent.  None of my kilns are computerized, alas, so it doesn't matter to me what the tables say.  I have to go strictly on heat work.  It's reproducibility that I'm looking for.

 

I mostly use my pyrometer to tell when it's time to turn switches and time to start watching the cones.  Though those are important functions.  My old thermocouple burned out a week or so ago, and I had to do a bisque without it.  Painful, having to guess at turn-up points.  But I'm glaze firing today with the new one, so I feel better.

[David Woodin]

I wasn't clear, I meant the bending part of the cone has to be 1 3/4" or 2 " above the cone pack. If your cone pack was 1 inch thick and you pushed the cone in to the bottom then what is left of the cone to bend is not 2"

David

[rayaldridge]

Okay, I see what you mean now. 

 

I try to keep my pats under 1/4" thick, which I suppose is why it's never been an issue for me.  Is there an accepted thickness for a clay pat?

[Judith B]

Wow, thank you so much everybody for your answers, it all makes sense now!

[Mark C.]

Keep you clay 1/4 to 3/8 thick and you will have no worries-the 8 degree angle is easy after you have done this a few times but Rays suggestion will get you dialed right away.

 

After reading about controllers crapping out for so many years on this forum not using cones is like taking your gas gauge out of your car. Hey its got gas and goes along fine until it runs out then you wish you had the gauge . Really no reason not to put a few cones in so if you need them you can view them,either in real time or after the fire. My ceramic career has been selling glazes that POP and cones are what I use to get there.

For me in a gas kiln its no cones no fire. I have added cones to a fire which was going after 1800 F buts that a story for those who are not weak of heart.

Mark

[bciskepottery]

I have added cones to a fire which was going after 1800 F buts that a story for those who are not weak of heart.

And members of the no-eyebrow society.

[David Woodin]

Okay, I see what you mean now. 

 

I try to keep my pats under 1/4" thick, which I suppose is why it's never been an issue for me.  Is there an accepted thickness for a clay pat?

If you make your pads 3/8" thick and do what you now do you will have a cone 2" above the pack.  I f you want taller packs that is okay but not as easy to get the 8 deg angle.  There is a symbol on the cone and its horizontal line is 2 " the top of this symbol is 1 3/4 inches so that is your guide for the proper depth to have the cone above the cone pack.

David

[Mark C.]

 

Okay, I see what you mean now. 

 

I try to keep my pats under 1/4" thick, which I suppose is why it's never been an issue for me.  Is there an accepted thickness for a clay pat?

If you make your pads 3/8" thick and do what you now do you will have a cone 2" above the pack.  I f you want taller packs that is okay but not as easy to get the 8 deg angle.  There is a symbol on the cone and its horizontal line is 2 " the top of this symbol is 1 3/4 inches so that is your guide for the proper depth to have the cone above the cone pack.

David

 

David you got me measuring large cones which I had not done in 35 years-they are 2 3/8 long and as you said the stamp is at 3/8 from bottom and ends at 2 inches. Since my spy plugs are 3 inch diameter I tend to make them taller for that kiln. In my small kiln I have 2 inch plugs so I make the pads shorter. What matters is where the depth  the pad hits the cone which as you said is on the side

I suggest everyone check out Ortonceramics.com and read up on cones.

I was taught how to make these pads by two Alfred graduates like you except they graduated in early 70's-they taught glaze calculation and clay body formulation classes at my collage.

With your industrial background you already know all about this.

After 40+ years now I can guess that 8 degree angle very well but it also the way the cones are made to sit so its really easy to see as Ray says by placing them on a flat surface and reproduce this.

Mark

[potterpat]

^{The cool thing about cone packs is that you can put them EVERYWHERE in your kiln. As you get to know your kiln, you will notice that there are places in the kiln, where if you place a pot with glaze A there, it comes out looking like the cover of the Rolling Stone (or CM), but the same glaze will come out underfired or runny, or bland, in a different spot. Putting cone packs in different parts of the kiln lets you know where your cold spots are, where your hot spots are, where the spots are with the heaviest reduction. So you can adjust accordingly. I fire to cone 10 reduction, but there are places in the kiln where I put some pots with cone 9 glaze- because its a cold spot, and some places where I stash some pots with a glaze with a higher melt point, because its a hot spot. I have a place near the top where I get the nicest reduction, so the ones I have high hopes for go there.} 

 

^{Someone mentioned "reading heat"- definitely a good skill! As you get skilled, you can see when its got a nice cherry glow, and 06 is about to bend. And when it gets to that yellow-white radiant color, cone 8 is down, and 9 is on the way down.}

 

^{I do use a pyrometer, but this is just to be sure that I have a rise in temperature going on- so that if I do have a stall, and I change one thing in the damper or burner air, that I can see if it helped. If not, I change it back and try something else. I use cones to tell when I have hit temperature, not the pyrometer...it doesn't know. My cones show what the heat is actually DOING.}

 

^{Just my 2 cents}

^Pat

^{in southeastern SD where the sun periodically makes an appearance...}