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Pottery by Penny

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    Pottery by Penny reacted to Dick White in Long Time Tried And True Slip Recipe Gone South   
    The original G200 Feldspar was mined in Monticello, GA, but the ore was depleted some 10 years ago. Another feldspar mined in Siloam, GA was similar except for a higher potassium content. It was trucked to the Monticello processing plant and mixed 70:30 with Minspar200, trucked in from Spruce Pine, NC, to recreate the old G200 chemistry. In 2009, the owners made an understandable economic decision to stop shipping the stuff around, and started selling the higher potassium product from Siloam as a new product which they called G200 HP. This was announced and well known in the industry, but many potters didn't focus on the name change and used the new HP product as if it were the old. Or they adjusted without changing their recipe notes for the name/content change. And there are zillions of old recipes floating around calling for G200 and unaware potters would use the new HP thinking it was the same. Also, some suppliers did their own 70:30 blending of HP and Minspar and rebagged it using the old G200 label. In 2013, the Silaom mine was exhausted. In the last year or so, yet another similar potash feldspar has been introduced with the G200 name, this time mined in Spain. It is labeled on the original 44 lb. factory bags as G200EU but often referred to in sales literature or on the smaller re-bagging by vendors simply as G200. So, depending on when you bought it, who you bought it from, and how much detail you went into with the supplier, you could have different stuff.
    Highwater is selling the EU product, but if you didn't know the back story, you probably wouldn't notice. And from a practical standpoint, the chemistry of the EU product is supposed to be similar to the old original Monticello G200/blended 70:30 G200HP/Minspar, just more expensive because of the shipping from across the pond. But similar chemistry does not always translate to similar performance in the bucket.
    Mark's suggestion about the 200 vs. 325 mesh of the silica may also change the behavior in the bucket, but without knowing for sure that you previously had one and picked up the other last time without noticing it, hard to say.
    That leaves us with Tim's excellent recommendation - titrate some saturated epsom salt solution into it a teaspoon at a time to flocculate it for better suspension.
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