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shawnhar

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About shawnhar

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  1. I will see about getting some welding glass, thanks! Tried the following schedule: Ramp Temp/hr Temp/hold 1 100 220/0 2 350 2000/0 3 120 2050/0 4 108 2150/10 5 -120 2050/10 Moving in the right direction but still pock marked, refired pots from previous firings were "better" but not healed. Pot on the bottom shelf is "almost" good, top shelf still riddled with holes but they are much smoother than previous. Not sure if I should increase the top temp or add more hold time. Even with a peak temp set well below ^5, it's still starting to bring down the ^6 cone.
  2. Hahaha, I wasn't sure it was blisters or pinholes or pitting. Read up on blisters and assumed that is the issue, created a schedule that slows down around the peak temp and started the kiln on lunch yesterday, it's now at 400F and I took a quick peek, cones look perfect and I didn't see any blisters. Fingers crossed! I have tried to look in the peepholes but I think my vision can't detect such a low contrast, once the kiln gets above dull cherry I can't see anything. I do only have one thermocouple, put cones in the bottom this time to see the difference, and a few of the blistered mugs to add mass.
  3. I have ruled out the clay, bisque fire and glaze by mixing pots fired at the studio and home. It is def an issue with my fire at home. The last piece I picked up from the studio was bisqued at home and fired there, came out with no blisters using that same turq glaze. Pretty sure the issue is the ramp up/cool down of the last 200 degrees, but the way my 6 cones are bending over is confusing and I'm not sure if I should be firing to a lower temp and a slow climb/cool around the peak, and what peak temp to use.
  4. Feeling a bit lost on my test results so far and looking for feedback please. My first glaze fire was fullish kiln load ^6 with 10 min hold and fired hot, 6 cone was drooped down on the shelf and I'm guessing was a soft 7. The glazes were pretty smooth but still kinda bumpy. Second firing was fullish kiln load ^5 with 15 min hold Med speed and fired hot I think, 6 cone was bent all the way over tip touching the shelf. All glaze was riddled with acne, little bumps with a hole in the middle Third firing was mostly empty kiln, used all the furniture I have and most of the shelves to add some mass but still a lot of empty space. Fired to ^5 with no hold Med speed. 5 cone bent over tip touching shelf and 6 cone bent 30 degrees. All glaze has the acne, not as bad as the second firing but still there. Fourth firing kiln loaded exactly the same as the third, but fired ^5 FAST speed, no hold, 5 cone bent over tip touching, 6 cone bent over 90 degrees. I thought running a fast glaze would create less heatwork and the 6 cone would be bent less, but that's not what happened. The pot on the top shelf is riddled with horrible acne, BUT, the pot on the BOTTOM shelf is way better, the acne is still there, but almost completely healed over (at least compared to the top pot!). I am hoping to understand WHY the acne is better/worse in each of these tests before I use a custom program for my next test. It "seems" like the more heatwork there is, the better the glazes are coming out, but that means I am firing more than a full cone over what they are firing at the studio just to get a smooth(ish) glaze, which is confusing.
  5. Firing 3rd glaze test....

  6. shawnhar

    Home Studio Information

    You need to actively vent the kiln fumes to the outside and also have an adequate intake of fresh air in the room with the kiln.
  7. Interesting... I have gotten a lot better at getting the clay up from the bottom, but I still can't make the tapered shape I want without using the "wooden knife" tool to carve off a little of the of the bottom and put the final shape on it before wiring it off. I have had "some" luck shaping the bottom with a wooden rib while throwing, but more often than not, that introduces a wobble, or I get the clay too thin down there because I can't feel it through the rib. It has made a big difference in my trim time too, not trimming for shape, just to put the foot ring on. I need to make/get one of those right angle trimming tools that grabs the clay as you trim off that bottom bit, half the time I mess up the bottom if I try to do it in 2 moves while the wheel is still spinning as the wooden knife pushes the clay back up against the pot or doesn't grab it right, etc...
  8. Bisquing ma test pots....

  9. shawnhar

    Advice for 1st glaze firing?

    Perfect info man! I am guessing that is what I will get with cone 5 and no hold, based on my previous result, if so I can put in a cone offset and add a hold, hopefully that will get me in the ballpark.
  10. shawnhar

    Advice for 1st glaze firing?

    Thanks Yappy and Stephen, just waiting for my test pieces to dry so I can do another bisque and then I will use those at ^5 with no hold, go from there. I have enough to run 4 test fires and hoping I will find the sweet spot.
  11. I saw a woman on utube that uses one in her throwing water. I wondered if you couldn't just keep a coffee pot full of water and keep putting some in, it appears Liambesaw has tried topping off with boiling water and it still gets cold fast though.
  12. I bet that is exactly true, I suspect no handles would be a tough sell in my area
  13. Thanks Joseph, all of those were 1lb 4 oz. of clay. I trimmed off 3 or 4 oz. from the bottom on most of them at the time of throwing, some much less and then carved foot rings in almost all. I did some with 1lb but I like the thicker ones, keeps my coffee warmer longer, the thinner ones with less clay "feel" like a better made mug...but my coffee gets cold before I can drink it. The final glazed mugs were 4 /2 to 5" tall. Thanks Rex, it would not have occurred to me to make handle-less mugs! You sell many like that?
  14. Thanks Min, that is brilliant regarding the mass, I feel really dumb now, wasting my mugs on the second firing when I could have just filled the kiln with shelves and furniture with a few test pots and next firing will do just that. Set the TC offset, use furniture and shelves for mass, and use a firing program provided by dhpotter, which was based on yours and Tom's recommendations, to slow the ramp up to the final temp, let it drop, then hold. First thing though is just do the TC offset and do a cone 5 no hold with a couple of test pots and witness cones, then go from there. Making my test pots tonight Thanks you everyone!
  15. Thanks Fred, sorry I wasnt clear. The first firing was cone 6 10min hold, and it overfired with ^6 cone slumped down, the glazes came out dark but they were mostly smooth, some slight blistering I think and some pinholes but not too bad. Second firing with new pieces was cone 5 with 15min hold, witness cones showed ^6 bent over with tip touching shelf, they came out blistered/tons of pinholes, so I refired those again, same cone 5 15min hold , they got worse. Guess I should have tried cone 4. I have to make a bunch of basic pieces for the next test fire in stead of wasting all my mugs on this, sucks losing them.
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