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shawnhar

Assessing the results of my 1st Glaze firing

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Skutt KM818 3"
Cone fire mode, medium, cone 6 with 10 minute hold
Clay: Highwater Buncomb White cone 3-6
Bisqued to cone 06 (except one cone 04 mug)
Glazes: pre-mixed local studio glazes rated cone 5/6, mixed about 2 weeks ago. White, Turquiose, Floating Blue

Firing time was 8hrs, 38min

Kiln was not packed tight, bottom shelf was just about full and top half of the kiln had some empty space, probably could have used a half shelf and put 4/5 more mugs in, but was afraid or ruining a whole load so left it somewhat sparse.
Overall I am pretty pleased with the result cionsidering it was my 1st glaze fire ine the "new to me" kiln. Several pieces ran but not too bad, that floating blue is notorious for ruining shelves at the studio. The glazes are much darker, and blended together much more, than I get at the studio. I love they way they blended, and they have way more texture, which I also love, but I do wish they were a bit brighter. Makes sense now that I know the studio fires these glazes to cone 5 with a 15 minute hold, and a great learning experience to see how much of a difference that is from my firing. A couple of small defects here and there but no pinholes or crawling and nothing ran down all over the shelf. As a first firing, I'd call it a smashing success!

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Your cones look like the kiln fired hot. For SSB cones the tip should be no lower than the beginning of the base of the cone. Granted we have different clay, but when I was firing the kiln to the bent state of your cones the clay began to bloat. Backing off the top temp by 10*F put the cone right in the sweet spot and no more bloating clay body. The kiln now fires to 2185*F with a  15 minute hold.

The floating blue looks like it could go on thicker to get a blue instead of a brown.  If you are pleased with the results is all that really matters.

The turquoise looks great! Is that Val's Turquoise? It is 1 of my favorites.

Specific Gravity - let it be your friend. 

First glaze firing in your own kiln, Priceless.

Edited by dhPotter
add SG

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Thanks dh, I think your'e right that the kiln fired hot, shame too cause I replaced the thermocouple right before I started this fire because the bisque cones were bent over like that as well. I was hoping the new thermocouple would change that but it did not. I suspect the elements are a bit worn and causing a longer run to create more heatwork and fire hot, just guessing there though. I sounds like you are firing to just above cone 5, is that correct? I thought about firing the next one to 5 with a 15 minute hold so I can compare with these results.

That floating blue is super thick in the bucket and I was worried it would run all over the shelf, if it had been much thicker I think it would have left some pools where this was only a couple of little bits mostly caught by the kiln wash. It's a tricky glaze but looks awesome when done right. Whoever mixed my glazes left them really thick and chunky, I have to get a seive and work on them, the white was so thick it looked like thick pancake batter and I watered it down a little but i think it needs to be thinned more. All the dips were no more than 2 seconds.

Thanks glazenerd! I thought ruining a shelf was a real possibility, lol.

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Ha, thanks Babs, I keep meaning to do that, but I really like it when the glaze goes right to the edge, it's a catch 22. 

I added some water and mixed the heck out of the blue and turquoise, glazed another 20 mugs and just started the cone 5 with 15 minute hold, I hope they come out a ton brighter. Made a couple with thicker blue, I bet they run....

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Looks great!

I looked up that clay you are using, at ^6 the absorption is 2%, at ^4 it goes up to 6%. If those cones in your picture are sixes then doing a ^5 with 15 minute soak will likely get you to ^6 as it looks like your kiln is overfiring. (might want to do a tc offset) If you only get to just past ^5 the clay might be a bit porous for functional wares intended to hold liquids. It's a good idea to run your own absorption tests.

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Thank Neil, I am waiting for last nights firing to cool but it showed a peak temp of 2172 at the end of the cone 5, 15 minute hold. Still have about 4 hours before I can get a look at the results.

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It is not just the temp reading you are trying to attain. It is the heat work that gets you to ^6. I program a top temp then the 15 minute hold gets the ^6 to where it should be. 

The last time I replaced the TC, about 6 months ago, the TC I received from Olympic was an inch longer than the TC in the kiln. The first firing after replacement was about a ^5.5 firing even with the 15 minute hold. The longer TC, it being an inch farther from the elements, threw the temp reading off by about 20 degrees. Did a TC offset and it worked fine. The ambient temp in the studio may be 85*F but the controller shows 65*F. 

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Never really got the point of the single cone. I mean yeah it tells you if you didn't hit your desired cone on that shelf  but that's only half the story. I think a cone 6 with 10 minute hold will/should be about cone 6 1/2, thus your 6 completely bent. Using a three cone pack will help you zero in on where you hit. With your settings, the first cone 5 would bend all the way, the 2nd cone 6 would bend almost or all the way and the third cone 7 should not have bent much, if at all. By not having the next cone up you really don't know how far past cone 6 your kiln went. You know it didn't under fire but you just don't know the top end.

Great pots, the only thing I would offer for both drips and nice even bottoms (if that's a goal) is to once you know your glazes (SG) figure out how much un-glazed space the bottoms need to  accommodate the glaze run and make a nice clean sponge turn after glazing to even up the bottom gap to be consistent all the way around. Most of mine are the same with the exception of Val's Turk which tends to run more. Will look like its off going in and come out looking nice and even on the bottom and the glaze run will close the gap, again if that's a goal of yours. My partner taught me this and really using the diamond pad on the bottom to make pristine and I think my pots look a lot more professional with this extra attention.  

  

Edited by Stephen

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There are a few tricks to help deal with runny glazes like the floating blue, and the Val's Turk. I usually do double dips of these, with the glaze thinned down a bit more than I normally would, and then dip first coat all the way to bevel, then the second coat an inch higher. Also helps to create a drip catch in the foot ring-bring the wall of the pot in a little at the foot ring, creating a ledge at the top of the bevel. This will help to slow the movement of glaze over the foot ring.

As to cones, I really think the cones are over fired. I fire ^6 to the touch down, no curl or second touch down, and ^7 is just starting to bend. I back off the kiln when ^6 touches 10% on all switches and hold about 10 minutes. However, my process is all by hand as there are no controls on my kiln but the switches. In the long run, without being there and seeing heat colors. . . all personal opinion.

best,

Pres

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Great looking mugs for your first go around, Shawn! Take heart in knowing that things will improve as you get more familiar with what your glazes will do at certain temps and methods of application. These are the first steps of a long and fulfilling journey!

JohnnyK

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The trick my teacher used to glaze to the bottom without drips onto the kiln shelf was to soak the bottom quarter inch for 15 seconds in water just before glazing. This way the glaze wouldn't adhere as much in that area- would come out thinner there, but there was still visual continuity.

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4 hours ago, shawnhar said:

Funny you mention that as I was just reading about it last night, apparently 2% is ok, but beyond that it gets iffy?

2% or under for stoneware should be okay but I would really suggest checking your clay, preferably at different cones. There will be a curve to the porosity figures if you graph them. Starting at being underfired they will go from very high to as tight as the clay can go at maturity then plateau then slowly go back up again if the clay is overfired to a high degree. (overfiring too much can increase porosity as materials within the body start to volitize)

 

 

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shawnhar, great results, nice colors and distinctively yours.  

i am interested in the triangular posts you are using as a base for your cones.   did you get them recently, and, if so, where did you buy them?   i use those posts for all my firings because they take so little room in the kiln.  i hope you are able to get the melted cone off the one inch one, that is one of my favorite sizes.   put a spot of glaze on top of a one inch, add a half inch and you have a perfect size for trays and plates.

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I really like the green and white color choice, and agreed it looks even better fired hotter. Not so crazy about the dull/warm/blackish-brownish stuff but that's just me, hey, I never like black/brown/gray mugs. Also you have my exact kiln. I noticed the very first load I fired in mine seemed to fire hot and everything that came after behaves normally and continues to do so. I did a 20 min hold my first fire and it was the only time things got runny, Neilestrick said my mistake was the hold time. Just a thought or two. Keep up the good work. 

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Wow tons of great feedback and tips! It will take me a while to respond to everyone but I wanted to say thanks to all of you.

oldlayy, when I bought the wheel/kiln they lady gave me everything she had and there was a box of kiln furniture with those and about 50 other pieces of various sizes and shapes. but those are the only ones i've used, I like em' too!

Yappy, I didn't care for the way the blue came out either, next firing came out more blue, will post results later but it did better at ^5 with the 15 min hold.

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Thanks to all!

dh, I did just that , cone 5/ 15min hold, on the second firing and it was much better, good info on the TC distance, never would have thought of that.

Stephen, make sense on the cones, I need to order some 7's so I have a spread, have some 5's and put one in the next firing. The ^6 looks good to me? Drips/even bottoms is a goal and the more stable glazes I am getting better at predicting, sponging the glaze consitantly off the edges is a skill it's self I am still working on. I looked up the recipie for my turq and it is not Val's, this one doesn't move much at all, very stable. I like, pristine, bottoms and I cannot lie, you other potters try to deny... Completely agree and that is the goal.

Pres, I think I need to thin the floating blue more, the fail below was a double dip, I knew better too, it took a long time to dry, but I wanted to push one mug and see. Good tips on the dipping, and adding a catch, and your firing details.

Johnny, thanks, I figure if run a glaze fire 3 or 4 times a week for a year, I'll be there, untill I change glazes, or get a new kiln, or clay...lol.

Gabby, I am going to try that next time, I also read about spraying water on certain parts to thin the glaze.

Min, thanks for the info.

^5 with 15 min hold came out much better overall, my Turq failed though, saw it was chunky and should have waited until I could deal with it. Taking it back to the studio tomorrow to have them look at it/seive it. I thought of refiring just the the green and hoping it would smooth out, maybe ^5 with a 20 minute hold or just putting them in with the next glaze batch? If by themselves the kiln would be mostly empty. I have some black mugs with little tiny burst bubbles on the inside I would add to the load hoping they smooth out as well.

Color is WAY better and I think the cones are what they are supposed to be, maybe a tad on the high side but I bet lower and the colors would not be as rich, which I like.

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I use a cat litter tray with a dense foam in it. Some folk use carpet.

The foam is wet not saturated . One can get a pretty good even wipe up and over edge if want depending on pressure exerted.

I.e. After waxing,

.dip your pots then rotate pot on dampened foam to remove drips and glazed edges..really speeds up process and lessens handling

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I don't have a sieve yet, I bought a paint mixer attachment for my drill and used that. Should you have to sieve glazes you bought as liquid 2 weeks ago? Surely folks don't sieve every time they glaze... Just if you notice it's chunky. I also picked up one of those hand held immersion mixers and I'm hoping the shear action will break up most of the chunks.

I tried the "wet foam rub" but the foam I used was too soft and too much glaze was rubbed off, I need to find some denser material. I have some boat carpet left over from a project and will try that.

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Yes, I sieve every time I glaze, unless it's next day, sometimes. But stirring up and observation should tell you, with experience, if it needs the sieve - for dipping. There's still something to be said for stirring up with your hand - you can feel the texture and consistency and you can test the bottom of the bucket for chunks. Obviously, you don't want to do that with, for example, a barium glaze, when you'd want nice long gloves.

Of course, for the sprayer, every refill gets strained. 

Get a good, bucket-sized sieve, ASAP. Save yourself from those avoidable fails. 

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