Ramp schedule for "slow and low" firing to cone 6

[Babs]

I have been playing with the leopard spotting effect of layering an iron shiny glaze with a white second layer..used to be popular as a hiigh fire in the 70s.

I read a blurb vy John Britt who wrote "fired on Slow and Low firing schedule"

Anyone know what the ramps are set at for thiis firing? 

 

[Mark C.]

Babs my guess is one thats Slow and Low firing schedule

[Babs]

2 hours ago, Mark C. said:

Babs my guess is one thats Slow and Low firing schedule

I get the slow but the low...!!!!

Reposition the kiln downhill a bit????

Thanks Mark, ever helpful,amazed what you come out with when you really put some thought into it :-)))), 

Gas low in the cylinder?

Better low in the kiln???.Dunno

Thought s.one may have worked it out..

 

 

[Hulk]

Looks like it's from one of his books

There's a "Exploring Cone 6 Glazes Together with John Britt's Book" FB group, however, one must be a member read/see anything (I'm not a member); the image above was posted to Flickr by Mr. John Britt.

[JohnnyK]

I tried one of his schedules that included the 500 degree ramp on my Cress kiln and it shut down on me saying that the 500* exceeded the capability of the kiln, so I reduced it to 350* and it worked. If you look at the fine print in Hulk's image it says that his kiln tried to shut down a couple of times thinking that the 50* was too low...it could have been that the 500* was too high...

[Sorcery]

500 is fast as hell IMO.

Sorce

[CactusPots]

You're doing 500 through quartz inversion.

[liambesaw]

I'm wondering if that's an ironic name?  And what's with the 10 minute holds? That's some bizarre stuff

[PeterH]

A few more "leopard spotting" pix and the firing cycle  @Hulk found at:

John Britt's Group Spotted Glaze Tests 2018 | Flickr
https://www.flickr.com/photos/160831726@N06/albums/72157694644585314

Looks like there may be some interesting tests reported in the Facebook group.

[Babs]

12 hours ago, Mark C. said:

Babs my guess is one thats Slow and Low firing 

.Thanks all.

I got a less dramatic result with my normal firing to Cone 6 but wondered on reading about the Slow Low stuff what the schedule was. 

some clays can handle a fast travel through inversion but that is FAST.

Thanks Hulk for fiinding that.

John Britt incredibly generous person.

 

 

[Bill Kielb]

6 hours ago, Sorcery said:

500 is fast as hell IMO.

Sorce

500 per hour is fairly fast. Nothing low and slow there except the final ramp of course. 2150 is a slightly derated 108 deg per hour final segment. Hold for ten minutes at cone 02 / 01 Seems odd.

[Babs]

Does the low part maybe relate to fact that this effect is easier to attain at cone 10?

[neilestrick]

I wonder if the hold at 202F is just to let things even out a bit. Ramping at 500F/hr in a single zone kiln would be akin to running it full on, which doesn't heat very evenly. It's not a very realistic ramp rate for most kilns, though, at least at the high end of the ramp. Too fast for all but small or high powered kilns.

I find that quartz inversion isn't usually an issue for most clay bodies. I've done 500F/hr ramps through quartz inversion many times with many clay bodies and never had a problem. Think of raku firings, where we blow through 1500F degrees of temperature rise in 20 minutes- most any stoneware can handle it. Bisque ware can handle a lot. The bigger worry is forms that don't heat evenly, like wide flat pieces or poorly constructed work that's uneven in thickness.

[Bill Kielb]

@neilestrick
couldn’t agree more and so do hundreds of thousands of successful firings every year.
Slow glaze on Bartlett controllers under cone fire is 400 degrees per hour. Fast glaze is 570 degrees per hour. Lots of stuff fired successfully for lots of years at those speeds. Bisque fires top out at 300 degrees per hour under cone fire with the Bartlett controller. Right through quartz inversion BTW. 

[Min]

@Babs, he hasn't been here for a while but you could try PM @John Britt .

[Babs]

4 hours ago, Min said:

@Babs, he hasn't been here for a while but you could try PM @John Britt .

Thanks Min. Won't bother John B.

Just interested

in hearing folk's mulling thoughts around this.

And what the actual schedule was.

Quite happy with what I got, though my under layer is a bit on the honey rather than  black so may add a percentage of black stain