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preeta

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Everything posted by preeta

  1. on the jar patch a tach only talks about ^04. while they do say bisque i consider that only good for greenware, not bisqueware that you fire higher than ^04. it worked pretty well when i used it for glazefire at ^04 which i consider low fire. but if you are firing over ^04 it does not work very well. i have had better luck with matte glazes at our school studio because in our studio the matte is the most stable glaze. also in your case gravity will play an important part.
  2. I am trying to understand what slow drying is and why it is important. is it just to avoid cracks? what happens when you fast dry? i understand some technical stuff like clay platelets and how they move. i am told some items should be really slow dried like plates, but others you can dry less slowly like bowls. if that is so why is that? i will be in 3rd semester community college class. i notice advanced students who are also TAs still have cracks in their bowls. apart from compression and or too much water used to throw could improper drying play a role for the cracks? i have been both throwing and hand building bowls (both pinch pots and slabs). i prefer the uneven feel so with the hand built pieces since there is no need for trimming (i build them in one sitting), maybe put slip on them and then air dry them. depending on the weather they are bone dry within a day or max two. usually the school candles especially if there are sculptural pieces going into the same kiln. i have not had any problems with cracking. does slow drying apply both to thrown and hand built pieces equally? in my classes from two different teachers the wheel throwing teacher emphasized drying more than the other teacher which was a handbuilding class (small handbuilt pieces which were done in one sitting). i have even taken a handbuilt bowl at leatherhard stage put it in the oven and baked it for 8 hours at the lowest temperature and it then went into the kiln and i have had no problems. to understand drying i've played with clay thickness and molds. thin clay 3/8" on the outside of the mold left for 3 hours on the plaster of paris mold without cover and then air dried without cover and the cracks appeared during glaze fire. same experiment with half inch thickness of clay and no cracks. i was told i should have covered them and slowly dried them before putting them in the kiln. what confuses more is i have watched youtube videos of korean production potters who throw bowls for an hour, set it out to dry in the sun for an hour and then throw for an hour and then trim the ones that they had put out in the sun. i am guessing its high fire clay as they wood fire, but does that make a difference? of course climate plays an important part - tropical wet heat instead of dry. is there a different philosophy towards drying between the east and the west? i have been scouring websites and books trying to understanding the process of drying but have not come across any so far. if you have any suggestions i'd welcome them B mix clay Bisque fire ^04 Glaze/2nd fire ^5
  3. have you tried a different clay body? sometimes in my experience i have found clear affects colour based on claybodies. do you have access to mayco clear glazes? or even Duncan's Pure Brilliance clear glaze
  4. i am surprised you are having this problem. i have never had that issue and i've applied it to both soft leatherhard, bone dry as well as bisque ware. i've actually also applied it as an overglaze and never had a problem. in fact i've applied it over a ^5 fired glaze and done a second cone fire at a lower temperature ^04 and not had a problem. i've never mixed any kind of liquid in it though. i've used a brush as well as bottle needle applicator. on B mix ^5 HOWEVER... whether underglaze or glaze - the powder IS smudgy after drying (not VERY smudgy but definitely smudgy). i dont handle the direct surface very much - meaning touching the surface of the slip or glaze or underglaze. after i apply it goes on the bisque or glaze shelf and then to the kiln. no extra handling what kind of clay body are you using? i agree with chris. i would not add any more liquid to jet black. just like she said i'd add it to the greenware. also i am wondering why you feel the need to wet jet black. maybe instead of a brush you should use a needle applicator.
  5. thanks oldlady. that does make sense. the only research i could find on were about amphorae saying the shape suited being in a ship's hull.
  6. I have only seen unglazed rims on bowls in museums i think either from africa or papua new guinea. their bottoms usually have pointy ends. i have not figured out what the purpose of those bowls were and why they were pointy ended. the unfinished rims i would imagine would not look good. would look incomplete. if you are going to slurp off the bowl you don't want rough rim on your lips. i wonder if cutlery will chip an unglazed rim over time. what i really do enjoy myself are round bottom bowls without glaze on the outside and glaze right up the rim. when i use nice clay or oxides i really like leaving the outside unglazed because i like the snug feeling as well as a good comfortable grip. i make the clay a little thicker and make cereal bowls to have hot soup in winter. warm bisque bowl on a cold winter morning is wonderful. fits the palm really well. i just did make a cup with cassius basaltic clay ^5 glaze and i wiped too much off the rim so the rim is really bare. looks fantastic. but unfortunately because of the exposed rim it has now become a pencil holder rather than what it was originally meant for.
  7. ibbloom no suggestion here. just curiosity. is this for a functional bowl? why do you want to leave the rim unglazed?
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