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Post by mohawkpiper on Feb 28, 2017 3:40:05 GMT -6
agreed that if you always do your rise and cooling the same then for you temp is just fine to use, i just meant that those that are reading your findings may see things happen at different temps if they do not do it like you but if they hit the same cone then they will so a cone is more accurate to use when transferring data from one to another.
The splotchy ground i do get on flat, not vertical, with a rutile ilmenite glaze. i do my best to not get it tho and do pretty well. when i do get it its more apparent at cone 016-014 than 018.
I dont layer glazes so i cant comment. i mostly strike vertical so my flat is limited and the splotchy is pretty miuch just one glaze i use and i do even get it on vertical if it ends up being thin.
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Post by Bernhard Schärf on Feb 28, 2017 5:25:02 GMT -6
I completely agree with you, that only the cone (temperature-time interval) is useful as a comparison. Also your hint that with (predominantly) horizontal or (predominantly) vertical pieces great differences arise, is also my experience. Especially the application in several layers with different glazes (like Arnie) has much greater effects on horizontal pieces. With vertical pieces, however, a faster mixing is observed by the flow of the glazes. Here are information of cobalt colors from the book "THE PHYSICS AND CHEMISTRY OF COLOR" by Kurt Nassau. Here is an example of cobalt yellow : Here is an example of Cobalt Green: I can only recommend the above book, who wants to understand the colors in crystals. Thanks Bernhard
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Post by jfox on Feb 28, 2017 13:18:41 GMT -6
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Post by Bernhard Schärf on Feb 28, 2017 15:53:51 GMT -6
Thanks for the info, however in my example the green is not "Rinmans green" (ZnO*CoO) but cobalt titanate (Co2TiO4 / CoTiO3 ?). Here is an example with greenish edges where I guess :"Rinmans green"
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Post by Bernhard Schärf on Mar 5, 2017 4:06:16 GMT -6
Here is a vertical piece with green-yellowish splashes similar to Arnies whitesplashes The micro crystals can be seen in detail. Here is only cobalt oxide in the glaze. Bernhard
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Post by jfox on Mar 5, 2017 9:01:47 GMT -6
way back when i had a cobalt stoneware glaze that broke bright pink at the margins,high in magnesium as i recall. lost all those formulas in a biblical scale flood on the Russian River in 1986
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Post by Bernhard Schärf on Mar 6, 2017 1:22:54 GMT -6
lost all those formulas in a biblical scale flood on the Russian River in 1986 Yes Jim, this is a pity, because Cobalt pink is very difficult to reproduce. Here is the example of Werner Gnegel: Bernhard
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Kuba
Full Member
SztukKilka in Old Formu
Posts: 111
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Post by Kuba on Mar 6, 2017 9:40:28 GMT -6
Am I right those are frit less glazes?
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gczop
Full Member
Posts: 202
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Post by gczop on Mar 6, 2017 10:05:58 GMT -6
Little confused by the alpha/beta willemite reference: was not aware that it did. Willemite is zinc/silicare: and crystals are similar in composition. Silica undergoes alpha to beta at 573C; but have not read anything in regards to zinc doing the same. To test effectively, you are going to have to reduce the number of oxides down to one at a time. with the multiplies you have going on now; would be nearly impossible to determine which one is doing what. Tom, re beta willemite see below, Gordon Formula: Zn2SiO4 Name: Named by Arthur Schleede and Arno Gruhl in 1923 for a Supposed [emphasis mine] second structural (metastable) state of willemite, a claim that was many years in verification. Although the mineral beta-willemite has the same structure as willemite and is therefore not the same beta-willemite as the authors had hoped, it does show anomalous yellow, rather than green, fluorescence in ultraviolet light. The above circumlocution is from a mineral site The term beta willemite is jargon mineral collectors use to describe willemite that fluoresces in the yellow-orange part of the spectrum. Therefore to identify a specimen as “beta willemite” it must be identified first as willemite and then demonstrated to fluoresce yellow-orange . In the scientific sense that alpha and beta quartz exist, beta willemite does not exist. G
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Post by jfox on Mar 6, 2017 10:07:02 GMT -6
Bernhard That is it, id like to work on it. been meaning to work on magnesia , Ive seen some interesting things in that area.possibly spinel structure
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Post by Bernhard Schärf on Mar 6, 2017 11:50:51 GMT -6
In the scientific sense that alpha and beta quartz exist, beta willemite does not exist. G Hello , I can not know what you mean by scientific articles, but here are just two of some sources that I have in this regard: Artikel alpha-beta Willemit 1Hello Kuba, the piece is from my friend Werner Gnegel and I can not just talk about his knowledge, please understand. I'll talk to him and ask him ... Thanks in advance for the understanding. Just Jim, that interests me very much, as synonymous Arnie wrote "a small change makes huge difference" .... border areas But that is also the wonderful thing about our work .... you always discover something new, mother nature will continue to astonish us ...... Bernhard
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Post by Arnie Benton on Mar 7, 2017 13:59:54 GMT -6
One question answered - I stopped the kiln for 2 hours at 1350F while it was cooling from a regular crystalline firing - produced no differences from usual cooling - so cooling down and then reheating is required for the effects of striking - cooling down to what temp before reheating is still an open question - Greg says he's gone down to 275 and reheated and gotten the striking changes - Tom suggests about 1050 might do it - I always go down to room temp and take pictures, so I'm not likely to try to find out -
Arnie
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Post by Bernhard Schärf on Mar 7, 2017 17:03:52 GMT -6
One question answered - I stopped the kiln for 2 hours at 1350F while it was cooling from a regular crystalline firing - produced no differences from usual cooling Arnie Thanks Arnie for the test. My thoughts are still that there is a difference in the kiln atmosphere between the stop from above and a second fire. Perhaps at the 2.fire but a purely oxidizing atmosphere while at the top from the atmosphere is perhaps somewhat reducing. Therefore, my idea of the cooling of the lintel ... Kiln easy to open, so that again an oxidizing atmosphere arises. My thought concerning the differences is for me the kiln atmosphere and not the 2nd fire. Bernhard
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Post by Arnie Benton on Mar 12, 2017 8:28:24 GMT -6
Here's a piece glazed in my usual way, with only Mn as a colorant, struck at 1375, shipped to Gordon for shortwave UV light examination - Besides how amazing it looks under UV light it doesn't turn yellow - so it's not beta willemite - if I'm understanding correctly. Can the magnetic forces, Curie Temp theory be tested in some way? Arnie
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Post by jfox on Mar 12, 2017 9:06:20 GMT -6
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