Sunday, March 3, 2013

Thanks again bloggers!

 Thanks to all of you that commented on my firing woes today.
I spent some time this morning weaving, and that settled me down a bit, and gave me time to think this through, absorb all of your posts and then do some reading in my pottery problems bible. I love this book and can almost always find the answers to my questions here.
It seems hard to believe that I over fired, my pyrometer just barely hit 2205f and I shut down the kiln. I was freezing and ready for supper. Is 2205 too hot? Of course, there is no way to tell if the pyrometer was correct, although it is very reliable when I bisque and raku fire. It is a likely reason for the bubbles though, it happens to me when I raku too hot, but it also happens when I raku too fast....  It would have been most helpful to put in cone packs. I don't use them and the one time I tried to there was no way to see them, there are no spy holes you can view them through, and they matched my pyrometer, so I thought I was good to go. It would have been helpful to have put them in with this firing to see if I did indeed overfire, which is likely.
The other cause for all of this is likely, as you said, rapid firing. The kiln jumped up in temp a couple of times and I got impatient at the end and bumped it up a bit. I ramped up mostly at 270 per hour. Is that too fast?  This is the schedule I have used in the past.....
I do know that it's not the clay/glaze fit, I have seen these two together and they are fine.
oh and ps: I was wrong in my comment about the one bowl that bloated, that's it in the top photo, beautiful bowl except for a tumor on the inside, it was the 266 clay, not the raku, and yes, that clay body is prone to bloating, again, maybe over fired. I knew going into this that 266 is a problematic clay, but it is a beautiful clay body, I love throwing it and I love the dark brown raw clay, I do not love the problems it brings with it though. Maybe I will hand build some dishes that aren't glazed with what I have left of it......
Oh well, whatever, I'm over it, ready to move on. I have some tiles I want to make for raku and I have little houses and pendants waiting to be raku fired.  I had this thing about bowls that I needed to get out of my system and so I did. I have no desire to make any more right now, maybe later...... for now I will just enjoy all of the great ones I have from other potters.
It would be nice to get one good firing when I put in this much work though. Ironically, the only survivor was a white bowl that matches my barns. This white satin matte has some possibilities. Haha, sometimes the Universe just shouts at you, doesn't it?

One other question: would it be worth a refire, or more fun to smash them with a hammer? I could take care of that right now!

Thank you all once again, I truly value your input!!!!!! Wise words and much appreciated sympathy :)


Sherry said...

You must be feeling better about this to some degree...your sense of humour is in full flight!! xoxo

Dennis Allen said...


Lori Watts said...

I find most pyrometers to be less reliable the higher you go. I mostly only use them in wood firing, and only to know if the kiln is climbing or falling, as you can't trust them temperature readings.
I'm sorry you've had a bad firing. Believe me I feel your pain! Maybe put those pieces out of sight for a while? Once you've made some new work you can decide whether it's worth it to try and revive these.

June Perry said...

Tracey, my latest bisque firing, I used the slow bisque firing schedule as listed in my Skutt manual; but just in case, I put a small cone 03 bar cones in the Dawson kiln sitter which I had installed as an extra safety feature when I purchased the kiln.
When I opened the kiln, the 03 was bent,and had tripped the sitter; and that was most probably because I did a ten or fifteen minute soak at the end, which was enough to take it up another cone.
And of course, glazes with a wide firing range can be problematical at the high end of the range, possible making them good candidates for winding up off the pot and onto the kiln shelf.

Vicki said...

I just read both recent posts this morning Tracey. So sad to see the results from the firing of your lovely bowls.
The glazes look like they are potentially beautiful - I'm sure you won't give up on them.

I don't have the wealth of glazing experience that your wonderful bloggers here do, so I have no valuable advice to give, I'm sorry to say. Still a glaze newbie.

But, I can say that I have cried over myriad failed glaze firings and spent much time trying to work out what I was doing wrong. I have learned A LOT from my mistakes and lack of understanding - especially as I had no one to ask, so Google helped me out many times.
I still have a looong way to go and will never stop learning.

I never used cones initially, so didn't know my kiln wasn't firing to schedule - even though the controller showed the "desired" temps were reached.
But when I did start using them, I began to learn more about my kiln, and this helped me adjust temps and programme schedules to fit accordingly. Not before much pulling of hair and gnashing of teeth tho'!

I know you won't give up, because you love what you do - the beautiful results show that. And when we love what we do, we forgive ourselves (sooner or later) and try again... and again :)

And, as for Mercury Retrograde, don't get me started!
He's already played havoc in my personal life this cycle, and I don't appreciate his tricks. Very disappointed.
Roll on the 18th, I say!! :)

ang design said...

smash em trace, it's rather fun but only if you're in the mood!!

Chris said...

I sometimes, well, way too often, produce hammer-ware which goes, subsequently, directly into the trash but I have a friend who has a heap out behind her kiln shed where she throws (and leaves) the bad ones. Breaking them is satisfying one way or another.

June Perry said...

Get a big hammer and go to it. Re-firing over fired pots, which I think they are, will not do any good.
Take the ten dollars or so for the re-firing and put it towards a nice bottle of wine which you can have after you're done with the hammer.:-)

Kevin Carter said...

Here is a short film on quality control by potter Jason Wason:

Tracey Broome said...

Alrighty, I will smash, haha!,!
Thanks, y'all definitely going for the wine tonight:)

Rosa said...

Oh, man! That sucks that the firing didn't go your way. From firing electric and soda, I think that ^5 is closer to 2167 than to 2200. (We do an approx. 25 minute soak at the top that brings it to ^5 1/2.) Anyway, that dark brown clay is a bear to work with (I use something similar). Bloating has never been a problem but I've found that the glazes are a difficult fit.

sheapottery said...

If they're over-fired, re-firing won't do any good.

Pinholes might smooth out if re-fired. Over-fired blisters won't.

If you under baked a cake, you could possibly put it back in the oven and maybe get it to come out right. If you burned a cake, putting it back in the oven won't help, even if you put more batter on it. Think of it like that.

Amy said...

my cone 6 firing reaches 2232. I only do slow fire--these days but will experiment with medium soon. so your highest temp isn't too high for cone 6.... maybe it's the pace at which the temp rises? hmmm