Still confused about first firing in new L&L kiln

[Girl on Fire]

This is in regards to the very first firing of a brand new kiln.

I have read posts here and elsewhere and I know @neilestrick recommends  a a slow bisque to cone 5 with a 3 hour preheat but I saw a very recent video from L&L instructing to program a glaze fire at medium speed to 04 with a 1 hour preheat. https://hotkilns.com/support/pottery-kiln-videos-links/first-firing-ll-kiln-genesis-control

There is also a video that shows firing a new L&L Glaze to Cone 5 at Medium Speed https://www.clayshare.com/firing-your-l-l-kiln-for-the-first-time/videos/gf11-01

So what is it? lol.

I have an Easy Fire  23-S...

 

As an aside, I have put 2 coats of kiln wash on the shelves and plan to put the third after the first fire. This was recommended  somewhere... Anything wrong with this?

 

Thanks!

Edited February 24 by Girl on Fire

[Bill Kielb]

2 hours ago, Girl on Fire said:

I saw a very recent video from L&L instructing to program a glaze fire at medium speed to 04 with a 1 hour preheat. https://hotkilns.com/support/pottery-kiln-videos-links/first-firing-ll-kiln-genesis-control

 

This video appears to be about a “break in firing” or first firing with a new kiln. My thought:  Maybe good to post what are you intending to fire (bisque / glaze) what cone you are firing to, any other info, like it’s heavy sculpture work not fully dry or It’s already bisqued ordinary thickness mugs etc….. to avoid confusion.

Edited February 24 by Bill Kielb

[Girl on Fire]

5 minutes ago, Bill Kielb said:

This video appears to be about a “break in firing” or first firing with a new kiln. My thought:  Maybe good to post what are you intending to fire (bisque / glaze) what cone you are firing to, any other info, like it’s heavy sculpture work not fully dry or It’s already bisqued ordinary thickness mugs etc….. to avoid confusion.

It would be the very first firing of a new kiln. 

[Bill Kielb]

I think either is fine for a first time break in firing. I don’t have clayshare so I can’t speak to that video.  The 04 firing in the first video is a nice soft test fire often used to season new elements. You can always practice a glaze firing later.

Edited February 24 by Bill Kielb

[Dick White]

There is some conflicting information about the first firing floating around, both from different kiln manufacturers, for different purposes, and even within the same manufacturer's instructions. L&L's printed manual has long instructed owners of their new kiln to do an initial break-in firing of the empty kiln (but with the furniture) slow bisque to cone 5 (yes, five, not oh-five) with a 3 hour preheat for the dual purpose of seasoning the elements to develop a protective oxide coating and to set the cement used during manufacturing to hold the kiln bricks together. Their newest manual indicates these instructions are for both the Dynatrol and Genesis controllers.

Conventional wisdom by some other kiln manufacturers instruct owners of their new kilns to do the initial firing slow to 04. This is consistent with the recommendation from the manufacturer of the Kanthal elements for seasoning newly installed replacement elements, again to develop a protective oxide coating on the wire. Out on the interwebs, many commenters who own these other brands of kiln will adamantly (but incorrectly) assert that new owners of all brands of kilns should do the initial firing to 04.

And now we have this new video from L&L for programming the first firing on a Genesis controller that instructs a glaze firing to 04 with a 1 hour preheat. However, if one looks around on the L&L website, there is another video for programming the older Dynatrol controller for the first firing that is consistent with the printed instructions, i.e., slow bisque to 5. Is the basic kiln constructed differently for a Genesis vs. Dynatrol controller that it would need a different initial firing? I don't work there, so don't take my word for it, but the conflict seems fishy to me. With 3 instruction sources to choose from (the printed manual and 2 videos), I would go with the 2 that are consistent, i.e, the printed manual and the Dynatrol video. But maybe that's just because I am a recovering accountant...

[Hyn Patty]

I second all of what D said above.  While the details may vary it all has to do with properly oxidizing the new elements, whether it is a brand new kiln or simply an element replacement.  In the case of a new kiln it is also about making sure all the kiln body itself is properly seated and set.  People used to think you needed to fire higher than cone 04 but I think the more up to date concensus is that cone 04 is the new standard most people go by.  Congrats on your new kiln!

[Girl on Fire]

1 hour ago, Hyn Patty said:

I second all of what D said above.  While the details may vary it all has to do with properly oxidizing the new elements, whether it is a brand new kiln or simply an element replacement.  In the case of a new kiln it is also about making sure all the kiln body itself is properly seated and set.  People used to think you needed to fire higher than cone 04 but I think the more up to date concensus is that cone 04 is the new standard most people go by.  Congrats on your new kiln!

Why does L&L include 2 ^5 witness cones with new kilns if their latest video shows firing to 04 for the first firing?

Still confused lol

[Hyn Patty]

Personally I have no idea why L&L does whatever it does.  I don't own that kind of kiln.  But for the most part no matter what brand of kiln you use, if it's electric, they all work about the same with only minor variations like manual versus electronic.  If in doubt just call L&L up on the phone and ask them.

[neilestrick]

L&L just recently changed their recommended first firing schedule from cone 5 to cone 04. Either will work fine.

23 hours ago, Girl on Fire said:

Why does L&L include 2 ^5 witness cones with new kilns if their latest video shows firing to 04 for the first firing?

Probably because they still have a bunch of cone 5's to use up. Use them when you do your first glaze firing.  I'll talk to them about getting some 04's instead.

Personally, I would do an empty glaze firing (just shelves) with the 5's because if your glaze firing is running hot or cold you can ruin a lot of work.

[Girl on Fire]

24 minutes ago, neilestrick said:

L&L just recently changed their recommended first firing schedule from cone 5 to cone 04. Either will work fine.

Probably because they still have a bunch of cone 5's to use up. Use them when you do your first glaze firing.  I'll talk to them about getting some 04's instead.

Personally, I would do an empty glaze firing (just shelves) with the 5's because if your glaze firing is running hot or cold you can ruin a lot of work.

Should I run an empty glaze fire after the first firing?

What speed do you recommend?

Edited February 25 by Girl on Fire

[neilestrick]

37 minutes ago, Girl on Fire said:

Should I run an empty glaze fire after the first firing?

What speed do you recommend?

You can just run the empty glaze as the first firing. Medium-Slow with a 1 hour preheat.

[Min]

From the Kanthal website, they recommend an oxidation firing to 1050C / 1922F for 7 to 10 hours. I'm thinking the people who hold for 7 to 10 hours are going to be few and far between if they mean a hold at 1922F and not a slow rise up to this temp. I typically hold for 3 when replacing elements. I don't know anybody who does a re-oxidation of the heating elements. I guess they are talking about a repeat empty kiln firing? 

edit: Euclids recommends holding for "several" hours also.

"To protect elements used under these conditions there is an element conditioning process that is desirable for FeCrAl elements, which requires heating the elements, in air, above 1830oF/1000oC, and holding for several hours. This develops an aluminum oxide coating on the outer element surface, which can dramatically improve element life.https://www.kanthal.com/en/knowledge-hub/heating-material-knowledge/operating-life-and-maximum-permissible-temperature/
 

"In such cases Kanthal® alloys are recommended, provided the heating elements are pre-oxidized in air at 1050°C for 7–10 hours. Reoxidation of the heating elements should be carried out at regular intervals."

 

Edited February 25 by Min
added another link

[Girl on Fire]

On 2/25/2024 at 10:55 AM, neilestrick said:

You can just run the empty glaze as the first firing. Medium-Slow with a 1 hour preheat.

I ran the first firing Glaze cone 5 medium slow with 1 hour preheat.

It took 13.20 hours to complete. Does this include the 1 hour preheat?

The ^5 witness cones I put on the bottom and top shelf seemed to overfire a bit.

 

Should I add an offset  when I do an actual glaze fire at cone 5?

(Bottom cone is on the left)

L&L E23S-3 with Genesis controller)

Edited February 27 by Girl on Fire

[neilestrick]

1 hour ago, Girl on Fire said:

It took 13.20 hours to complete. Does this include the 1 hour preheat?

Yes. And the 1 hour preheat actually takes about 3 hours  because it takes about 2 hours to get to the preheat temperature before it starts the preheat time.

Try a cone offset of about -15 degrees for starters. You're not over by much.

[Bill Kielb]

5 hours ago, Girl on Fire said:

The ^5 witness cones I put on the bottom and top shelf seemed to overfire a bit.

 

Those are really really close. For the self supporting cones I would not embed them in a little wad of clay. It actually raises the surface making the tip touch just a bit sooner than expected and it can also make it difficult to set the cone evenly on its base changing the natural design angle just a bit.

[Girl on Fire]

19 minutes ago, Bill Kielb said:

Those are really really close. For the self supporting cones I would not embed them in a little wad of clay. It actually raises the surface making the tip touch just a bit sooner than expected and it can also make it difficult to set the cone evenly on its base changing the natural design angle just a bit.

That makes sense. I was overly cautious about the cone sticking to the shelf.

Noobie move, I know.

I have kiln wash on the shelves. Do I need to worry about the cone sticking?

Should I not offset the cone?

[Bill Kielb]

7 hours ago, Girl on Fire said:

I have kiln wash on the shelves. Do I need to worry about the cone sticking?

Should I not offset the cone?

Cones ought not stick especially if your shelves are kiln washed. Cones are made of glaze, generally they will not fully melt and liquify until they are fired approximately four to six cones higher than their rating. So a cone 4 cone ground up would melt at about cone 10 pretty nicely. That’s a pretty large oops of an over firing so it’s pretty hard for them to seriously stick.  For self supporting cones the bottom should be flat and reasonably level as the angle they are made and gravity ensures they bend at their calibration. Offsetting them so they do not collide with one another in a cone pack is normal. For self supporting, just try and make sure they are placed flat and level as practical. If you are worried roll out a smooth small cookie or waster slab that is flat for them to sit on and same elevation at base and tip.

The guidance I always used is below. Notice there are only one to two degrees difference between 4:00 and 6:00. Pretty perfect has a range to it that happens quickly as the cone bends past 90 degrees.

 

Edited February 28 by Bill Kielb

[GEP]

In my experience, self-supporting cones can stick to the shelf if you overfire them just a little. They’re not supposed to, but it happens! As @Bill Kielb said, if you kiln wash your shelves, this is not a problem. I do not kiln wash my shelves, so I have had to chisel off some stuck cone bits. 

My solution to this is to use cone plaques, the kind that have holes in one side for holding non-self-supporting cones at the correct angle. I use the underside that doesn’t have holes, put kiln wash on that surface, and place my self-supporting cones on them. Any small piece of old or broken kiln furniture will work too.