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Strontium matte questions


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#1 pricklypotter

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Posted 05 November 2012 - 02:40 PM

Hi,

I've tried this recipe for a cone 10 reduction turquoise matte (I found it online):

Neph Sy 50
Strontium Carb 38
OM4 6
Silica 6

add:

Copper Carb 3

I know it's low on silica.

I quite like the colour, turquoise where thin and almost black and matte where thick, and the nice, dryish frosty surface. In my little line blend of adding the copper 1% at a time, the 1% tile reduced to a matte pinkish tone, the 2% tile partly reduced, and the best turquoise was at 3%. I was thinking I could add 0.5% to 1% more copper to see if it improves more.

My problem is that it crazes on my clay bodies (plainsman P700 and SPS Kutani).

The problem is visual since I am not going to use this in contact with food.

I was thinking of fixing this in three different ways:

0. adding silica until it's within the acceptable limit, and risk making it shinier or somehow changing the nice colour response
1. adding (5%?) zircopax (this also adds silica)
2. substituting spodumene for some of the neph sy, to replace some (definitely not all!) of the KNa with Li.

My direct question is how to do (2), would a mole of Li for each missing mole of KNa work?

And the more general question is which of these approaches would seem more promising.

Thanks!

PS for (2) I thought of matching the flux mole for mole, then balancing out the remaining alumina with clay and finally balancing out the remaining silica.

#2 Marcia Selsor

Marcia Selsor

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Posted 06 November 2012 - 06:45 AM

I adjusted a glaze that was crazing with very little silica...like 0.2% Do a few tests. It doesn't take much to tweak a glaze.
Marcia




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