jd
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Posts: 12
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Post by jd on Jun 15, 2018 7:39:23 GMT -6
Ok, I have over the last 4 firings lost it! I have been using a version of Galaxy and have some good results. However over the last few firings I have lost it, as the glaze now has a dry feel to it and I can not seem to get it thick enough. Is it me or is this just not fluxed out enough? Too thin? I have tried several different application methods and even mixed a new batch of glaze. Input please? As I think I may just go crazy from the fickle Crystal Mistress.
Here is a picture of how it can turn out, both fired in the same firing close to each other. The Bowl was just glazed and the bottle was about 4 months old from its glazing.
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Post by mariewright on Jun 15, 2018 14:58:07 GMT -6
That bowl looks to me like it did not get a good melt. How do your cones look from the good fire to this one?
Marie
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Post by tileman2 on Jun 15, 2018 15:28:46 GMT -6
This May or may not apply: but a good time to bring it up. Lithium Carbonate is one of the only elements that degrade over time. Fresh lithium carb. Usually has a PH of 11.0. Exposure to sunlight, storage in plastic container .( will leach), or prolonged heat can and will degrade lithium down to under 10.0 PH. I have tested it as low as 9.55 PH. Constant exposure to heat and humidity degrades potency as well. PH matters: it will effect the melt. Not always, but often times "granular feel" means soluble migration.
Whiting: 8.3. Potash: 8.9. Nep Sy 9.3. lithium carb. 11.0 fresh. TSP 13.25 porcelain 8.35 typical. Stoneware 7.65 typical.
Tom
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jd
New Member
Posts: 12
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Post by jd on Jul 1, 2018 13:16:41 GMT -6
Marie, Sorry for the delay I was out of touch for a while. I am running a firing now with new cone packs and will let you know. I am also woundering if I do not have a Thermocouple issue and need to add some off set or just replace again. I usually change them about every 10 or so cone10 firings. and I agree on the melt, it is what my gut and a few friends have mentioned also. I am also trying a little more flux as my top temp on this firing is 2355 with a 20 min hold.
Jeff
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Post by Arnie Benton on Jul 1, 2018 17:42:36 GMT -6
Some thoughts -
Firing without using cones, even with the best thermocouple, is not a good idea. There's a big difference between air temperature and heat work.
You could have a type K thermocouple that quickly becomes grossly inaccurate.
your kiln could be wired for a type K and you're using a type S or the other way around.
I suggest using a type S and making sure the kiln is properly wired for it and using cones - I usually just use a cone 10 self standing cone in each firing and get pretty consistent readings of cone 10 at 45 to 90 degrees bend in all my firings.
I don't follow the usual firing schedule of heating to top temp as quickly as possible. I think that just causes the elements to burn out more quickly.
I heat the last 200 degrees at 80 degrees per hour and get my cone 10 bending at 45 degrees when the thermocouple reading is 2295 with a 10 minute hold.
Work well with all cone 10 glazes I've tried.
Arnie
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Post by mohawkpiper on Jul 4, 2018 21:00:58 GMT -6
i dont think it has anything to do with heatwork, cones, elements or temp or whatever. it was mentioned that other piece (third pic) was in the same firing... and that one looks spectacular. i feel the problem lies in the new glaze... maybe a messup or bad chemicals or something.
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jd
New Member
Posts: 12
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Post by jd on Jul 5, 2018 15:07:49 GMT -6
I agree with both of you, this glaze has worked in the past and in this firing in question. One of the better firings I had in the last 4 was when I lost an element at Temp and the system shut it self off with no holds at all. I am thinking that I will learn and learn and learn on these glazes and firings with out end. I did go in and flux the glaze a little more on the next firing and everything turned out great!
Arnie, I am looking into S thermocouples now just found a source where they are reasonable and need to get them and some S type extension wire ordered. Then with the skutt kilns I have its just a program change to the S. I hope to get this done. You are right on the K, which is what I am using now. I change them about every 10 high fires, but I am looking forward to going to an s type thermocouple. I am also in the process of changing out the elements in the my high fire kiln as I have been burning one element out about every three firings.
Thanks for all the input more things to think on and learn.
Jeff
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