First cone 6 glaze firing

[Valarie]

I will be doing my first cone 6 glaze firing soon.  I have an old Duncan es820-2  teacher kiln that so far has worked well .

My question  is that I did not put wax resist on the bottom of my pieces and now I am concerned that if I set them on stilts ,they could possibly droop or slump? 

I am also  considering using a cone 7  in the kiln sitter so that I can hold the temperature longer (soak )for the cone 6 glazes. Any suggestions?

[Bill Kielb]

4 minutes ago, Valarie said:

I will be doing my first cone 6 glaze firing soon.  I have an old Duncan es820-2  teacher kiln that so far has worked well .

My question  is that I did not put wax resist on the bottom of my pieces and now I am concerned that if I set them on stilts ,they could possibly droop or slump? 

I am also  considering using a cone 7  in the kiln sitter so that I can hold the temperature longer (soak )for the cone 6 glazes. Any suggestions?

Are the bottoms all glazed, just wipe them off comes to mind? Post some pictures here, that will likely help a bunch. If you have cone 6 glaze and clay, not sure why you would fire to cone 7 as well. Overfiring is truly not any better than under firing so I am unclear why any soak is even contemplated. I am not sure I understand, can you explain a little bit of the why part?

[Valarie]

I  had read that using a cone higher  in an older kiln would ensure that it fired to right temp without it shutting off to soon.   I also was looking at different glaze schedules and saw that  a "soak "  was suggested at the end of the firing. Some of the bottoms  are glazed and others are not.

[Bill Kielb]

Still pictures would help explain. Can you just wipe the bottoms of those that are glazed and remove all traces of glaze? Again, overfiring things is not better, Soaking things at the end might be of use but in general, firing them to their prescribed cone is best.
An end of firing rate of about 108 degrees per hour in the last 200 degrees of your firing matches the center column on your Orton chart and that works quite nicely for most glazes and thrown pottery. If possible, fire test tiles first to confirm you are firing to cone and you will get the look you are seeking, in general try to fire to cone, matching clay and glaze.

Since this is your first firing, why not test out firing to actual cone. Use some free standing cones  or cone packs throughout the kiln to confirm the calibration. Place only test pieces inside so you do not risk ruining your finished work.

It is customary to use a cone 5,6,7 cone pack so you will know what it actually fired to. In reading, this will often be referred to as guide (cone 5), firing (cone 6), guard (cone 7)

Here is a little reading about cones https://ceramicartsnetwork.org/daily/clay-tools/ceramic-kilns/how-to-make-a-cone-pack-for-your-kiln-firing/ you can use freestanding cones in the same way to create a cone pack.

[shawnhar]

7 minutes ago, Bill Kielb said:

If possible, fire test tiles first to confirm you are firing to cone and you will get the look you are seeking

THIS!! times 1000 percent.

 I had 3 full loads of mugs that were all ruined until I figured out I needed to dial the kiln firing in before firing my "real" pieces.

[Valarie]

I  had read that using a cone higher  in an older kiln would ensure that it fired to right temp without it shutting off to soon.   I also was looking at different glaze schedules and saw that  a "soak "  was suggested at the end of the firing. Some of the bottoms  are glazed and others are not.

Thanks , I will try a test run first.  Just a few pics of pieces going in for glaze . 

 

[Bill Kielb]

Those pieces all can have the glaze wiped off the bottom, no need for stilts. Wax helps keep the glaze from sticking to the pot, but even waxed ware need the bottom double checked and lightly wiped to remove any leftover glaze from the bottom. Those are nice pieces, I would suggest to test first until you get a little experience firing. Generally If your clay is cone 6 then your glaze ought to be cone 6 and your goal should be to fire to cone 6.

[Valarie]

I  had read that using a cone higher  in an older kiln would ensure that it fired to right temp without it shutting off to soon.   I also was looking at different glaze schedules and saw that  a "soak "  was suggested at the end of the firing. Some of the bottoms  are glazed and others are not.

Thanks , I will try a test run first.  Just a few pics of pieces going in for glaze .

 

Thank you

 

[Min]

1 hour ago, Valarie said:

I  had read that using a cone higher  in an older kiln would ensure that it fired to right temp without it shutting off to soon. 

If this kiln is new to you I'ld check the kiln sitter is calibrated properly then put your small cone or bar, (bars are more accurate, cones are somewhat adjustable) and fire to cone 6. (link below on how to do this) It's probably going to take a few firings to learn how your kiln fires. 

1 hour ago, Valarie said:

Some of the bottoms  are glazed and others are not.

 

Easy way to get the glaze off the bottom of pots is to wet a piece of thin foam, carpet scrap, or even a few layers of fabric then turn the pot on the wet sponge. Gives you a clean glaze line around the edge. Give them a final pass with a clean sponge. Since you are glaze firing for the first time I'ld suggest a fairly deep glaze free area of at least 1/4" in case your glazes run more than expected.

edit: link showing how to calibrate a sitter here.