Karen Latorre on fri 20 jul 07
I responded to Dan offline, but in case anyone else is following this, I'm
using the Standard MDT set.
regards,
Karen
www.karenlatorre.com
>From: daniel@clayosmos.com
>To: Karen Latorre
>CC: clayart@lsv.ceramics.org
>Subject: Re: Winkelmann and Schott COE Figures AND an INSIGHT question
>onCOE
>Date: Thu, 19 Jul 2007 12:28:39 -0500
>
>Hi Karen,
>
> A quick response before I have more time to digest all that you have
>said.
>
> 1. I agree that the boron thing is problematic given the behaviour of
>3134/F12. Thought of that at the time, but figured better to toss it out
>there.
>
> 2. COE figures are calculated from test series of glazes that use a
>number of glazes of various compositions and then measure their
>expansions. They then plot or calculate the contribution of various oxides
>to the expansion. David Hewitt had a really good paper on his website on
>this comparing a number of the key sets of values. Not all researchers
>calculated values for the same oxides, alas. And of course, they don't
>always the same results :) I don't know what values Insight uses for its
>default COE set. So there could be something there. I had a problem with
>my insight MDT until night before last. I will look further into this and
>see what's up. It certainly makes sense that the COE calculations could be
>at fault in this confusion given the evidence. Your method sounds fairly
>well controlled so that's good. Can you let me know which MDT you are
>using. I generally use Ron Roy's and just downloaded the latest from
>Digitalfire the other night.
>
> Since David pass away his site is offline, but the content is available
>in the Web Archive at :
>http://web.archive.org/web/20061109202618/http://www.dhpot.demon.co.uk/.
>Look for the article on Calculating Crazing.
>
>Thx
>D
>
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Karen Latorre on sat 21 jul 07
Hi Dan,
I've finally gotten a chance to review the Hewitt/Bailey paper you
suggested. I notice that some of the COE sets do not have values for all of
the oxides. One of these oxides that is missing in one of the Winkelman and
Schott sets (the % weight cubic) is for Boron which is in both of the sets
of frits where I am seeing a discrepancy between the INSIGHT and the W&S COE
results. I'd guess that in calculating our COE for glazes, the INSIGHT
program is using the values for the oxides available, and not considering
the other oxides at all, therefore the difference between the COE order when
using the W&S set versus the INSIGHT set (assuming of course that they're
using the %weight cubic information where B2O3 is missing).
With the above assumption, I have another possible answer to the
discrepancy.
Given the help I received from you and Edouard I will go forward using
the INSIGHT set of values for my glass testing. A quick review of the
INSIGHT manual found an xml string that seems to indicate that the value set
used under the "INSIGHT" group is taken from W&G (West and Gerrow?). Can
anyone confirm this?
Thanks
Karen
www.karenlatorre.com
>From: daniel@clayosmos.com
>I don't know what values Insight uses for its default COE set.
> Since David pass away his site is offline, but the content is available
>in the Web Archive at :
>http://web.archive.org/web/20061109202618/http://www.dhpot.demon.co.uk/.
>Look for the article on Calculating Crazing.
>
>Thx
>D
>
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