O,K i got a bag of 325 custer from continental clay in minneapolis Minnesota in march 2017 i sent in some to get analyzed by ALS global. i put pictures of the sheet in case you think i am fooling you it is not what is listed on the web site it is sample NO .5 the others are anoka sand i am working with . Hear is the current analysis of Custer feldspar 72.47 silica 15.24 alumina, .27 Iron. .25 calcium , .08 MG, 3.45 sodium, 7.42 K20 0.01 titanium .26 phosphate it is a potassium granite so make your changes as needed , fellow potters
Custer Has Changed. Chemical Analysis Is In For March 2017
Posted 30 March 2017 - 09:40 PM
Kaolinwasher, thanks for checking into this. I am not the slightest bit surprised at this, actually I am perversely comforted that the rant I have been on for at least 5 years is still borne out by yet more evidence. Your numbers are very close to Ron Roy's published findings several years ago and my data from 2012. As I have said before, I don't mind that the numbers change over time. It's a natural material and Mother Nature moves. What I mind is that Pacer continues to insist that there is no change in the analysis from 10 years ago.
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Posted 30 March 2017 - 11:29 PM
Posted 31 March 2017 - 05:37 AM
ALS global's method "ME-XRF06" is an X-Ray Fluorescence analysis of a fused bead -- a typical method for a "whole-rock" "major element" geochemical analysis of pulverized rocks. The powdered sample is mixed with a lithium borate flux, melted, and then cast into a glass disc, which is then analyzed with a wavelength dispersive XRF spectrometer....
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Posted 31 March 2017 - 11:11 AM
I just talked with Mike ,at continental clay where i got the 325 mesh custer and he said that that load was from june of 2016 and they just got a new load in . he said they had problems with the jasper stone lining in the ball mill that was contaminating the feldspar a wile back . But mike said they always figured custer for having 8% potash and not to pay attention to the posted amounts on Custers Web site . But it has changed as Ron roy posted and now my analysis it seems to be staying the same since 2000 and 2012 and 2016 its a good material and i would not stop buying it my problem was i just want to know whats in it so i can make my calculations. Also mike said you can get the analysis from them on every new load which may change a little but is close to what i got and ron roys.
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Posted 31 March 2017 - 01:16 PM
THANK YOU for your service to the field.
Adjunct Professor of Ceramics; New Hampshire Insitute of Art
Former Guest Professor, Wuxi Institute of Arts and Science, Yixing, China
Former President and Past President; Potters Council
Posted 01 April 2017 - 10:40 AM
This is my latest body test using the new Custer feldspar. 25% T-6 kaolin 25 champion ball clay,25 Custer feldspar and 20% Purple sioux quartzite, It vitrified, did not craze, did not boat . it does have some tiny Iron specks, But if I used 25 i think it would have broke on cooling now with the new 72.47 silica in custer . The tests on the bottom left and right are stone tests , The one on the right is a magic rock , and it flattened out nice. Its from a huge bolder , have to get more of that . One thing i did is make sure i bisqed to cone 04 in oxidation that seems to have eliminated the blistering of the clay body.
Posted 21 April 2017 - 09:59 AM
I have been liking the custer feldspar . I got a porcelain to work very well with it 25 T-6 25 champion ball clay . and 25 custer and 19 flint with 1% Iron very good body for chin blue and that typ of glaze . plus its granite composition makes it useful for many glazes. I know it cost more to froth float out the feldspar which would give something like Mahivar in composition so they have probably went for the cheeper option of just leaving the quartz in one reason its less expensive. but still a Dang good spar I like it hope they keep it the same Gunnar R
Posted 10 May 2017 - 11:20 PM
I'm wondering if the test method used by pacer and whatever is used by plainsman clays is different than the one mentioned above and whether that is responsible for the discrepancies with the test done for kaolinwasher?
I had reps from resco tell me to my face that goldart didn't have a sulfur problem, but testing revealed that it was at least 10x higher in sulfur content than the fireclay we used at the time. And mine eyes and nose didn't lie to me when I smelled it coming from the kiln and saw the damage it was doing to the kiln with every firing. Goldart gone, sulfur problems gone.
I'm going to bring some of the custer feldspar we have to a lab and see what they say the potash content is, I guess. There are people who do soil testing and such at the university where I work who have helped me in the past.
Thanks for having the tests run that you did, and sharing them with us!
Posted 12 May 2017 - 09:30 AM
The information on digitalfire is not based on their own independent lab testing for all those materials, but is whatever the producer published. The problem with Custer is Pacer refuses to acknowledge that current laboratory testing consistently reveals that the content of the material they are selling now is far different than the material they were selling 10 years ago, and thus they continue to publish the obsolete materials analysis.The exact ceramic oxide content doesn't matter to their main customers (e.g., paint, rubber, and abrasives industries) so they just obfuscate.
Posted 12 May 2017 - 09:57 AM
This made me think they had sent out sample(s) for testing at some point. I could be reading that wrong, though.
Posted 18 May 2017 - 07:41 PM
they must grab one pure chunk of feldspar frome the mine and it would give that number . if they are that far off that is some horrible variation, i would tend to beleive somthing funny is going on i like the new custer granite anyway hope they keep it the same
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