jammy43 Posted August 21, 2014 Report Share Posted August 21, 2014 Wondering how substituting Grolleg in both clay & glaze recipes with EPK will effect results. I have both stoneware & porcelain ^6 clay recipes that call 25% Grolleg, and i'm thinking due to cost of switching with EPK. Link to comment Share on other sites More sharing options...
Biglou13 Posted August 21, 2014 Report Share Posted August 21, 2014 as you know its not as white, nor as tranluscent it has different trimming chacteristics as well as drying charteristics i have been reducing amount of grolleg for cost factor and replacing PARTIAL amount of kaolin with EPK firing wise and glaze wise i have yet to see difference im in florida and epk is pretty much local clay for me you should see my gallery for pictures of edgar mining home of epk. its a bit grey when wet, and dry in bag, it dries white, and is a bit off white when compared to grolleg based clays. i also will use part 300mesh silica, to keep that softer feel and trim feel i tend to dry epk clay a slower it tends to dry on skin while being wetter under surface im a big fan of epk, prolly have 5 bags in storage right now if you have more questions let me know or pm me Link to comment Share on other sites More sharing options...
neilestrick Posted August 21, 2014 Report Share Posted August 21, 2014 In most glazes you won't see any effect. EPK is slightly higher in Titanium, so that can have a small effect, but for the vast majority of glazes it won't matter. EPK bodies can still be translucent, but for most people that's not an issue anyway. As Biglou said, there will be a slight color difference, but in cone 6 oxidation it won't be nearly as noticeable as in reduction. If your recipes only call for 25%, the other clays in the bodies will already be affecting the color anyway. HERE is an interesting thread from Clayart in which Ron Roy discusses kaolins with some other tech guys. According to Ron, EPK is the whitest of the 4 kaolins they use at Tucker's, including grolleg. Grolleg, however, vitrifies at a lower temperature so you can get more of it into a translucent body than with EPK, which improves workability. Interesting stuff! Link to comment Share on other sites More sharing options...
jammy43 Posted August 21, 2014 Author Report Share Posted August 21, 2014 Thank you both for the information - Neil that was a very interesting thread - great to have Ron Roy have the testing results of both materials. Link to comment Share on other sites More sharing options...
Diz Posted August 21, 2014 Report Share Posted August 21, 2014 Thanks so much for the info!! Today I was mixing some glaze tests and there was mention of both grolleg and EPK within some of my test recipes. EPK I have so that went into the glazes. Then I came in to 'do my research' via a question placed on this forum! I'm glad others have the same questions I do and it makes me feel good to know that I have a forum to get answers to my questions. Link to comment Share on other sites More sharing options...
Biglou13 Posted August 22, 2014 Report Share Posted August 22, 2014 Jammy care to share your clay recipes? Link to comment Share on other sites More sharing options...
jammy43 Posted August 22, 2014 Author Report Share Posted August 22, 2014 Sure Lou I'm looking at using/trying Jeff Campana's porcelain: ( trying to source C&C ball clay in Canada) 25 Grolleg Kaolin 10 C&C ball clay 10 Tile ^ kaolin 35 Minspar 200 feldspar 20 silica 325 mesh 2.5 bentonite L-10 white And using Cushing's stoneware recipe: White Stoneware Throwing Source Cushing's Handbook (#2 p.37) Name VC Vitreous White Cone 6 Note White, very strong body Recipe Grolleg 25 C&C 25 Kona F-4 30 Frit 3124 4 Flint 16 Macaloid 2 i picked these two for the similarity in materials and therefore cost. Link to comment Share on other sites More sharing options...
Biglou13 Posted August 23, 2014 Report Share Posted August 23, 2014 Jammy both of those made my short list, good choices Last body I made was C6 Clay Body - from Val Cushing: EPK Kaolin 35 Tile 6 Kaolin 15 Nepheline Syenite 23 Flint 22 XX Sagger Ball Clay 5 Bentonite 3 I subbed out tile most of tile 6 with grolleg .... I was going for more traditional ish porcelain I'm going to throw some of this tomorrow. I feel using grolleg in stoneware is bit of a waste. Grolleg definitely has a feel to it but I think you can get the same with epk and 300 silica, and slurry mixing. I have - bag I'd c&c I haven't used yet. When I do make my clays I use a slurry method. Which I'm told is superior to standard method. I even end up lowering bentonite in recipes because clay can be "too buttery". Nonetheless im still interested using the c&c. Many here say its night and day difference over other ball clays. Eg om4. #5 So I've basically given you a few of my secrets Slurry mix clay Sub out portion of 200 silca with 325. Age clay with moldy rag. Link to comment Share on other sites More sharing options...
neilestrick Posted August 23, 2014 Report Share Posted August 23, 2014 C&C is my favorite ball clay by far. You'll love it. Grolleg is indeed a waste of money in stoneware clays. Just go with a cheaper domestic kaolin. With ball clay and other stuff in there you won't really notice much of a difference in feel or color anyway. I still have a hard time with people calling it porcelain if there's ball clay in it. That's a white stoneware in my book. Link to comment Share on other sites More sharing options...
Biglou13 Posted August 24, 2014 Report Share Posted August 24, 2014 big thanks to ^ that guy. I've become a porcelain snob!! Link to comment Share on other sites More sharing options...
Mark C. Posted August 24, 2014 Report Share Posted August 24, 2014 I've become a porcelain snob!! Welcome to the white world of clay Mark Link to comment Share on other sites More sharing options...
Biglou13 Posted August 25, 2014 Report Share Posted August 25, 2014 That ^guy also is responsible after seeing one if his pieces it started me thinking?..... Link to comment Share on other sites More sharing options...
bciskepottery Posted August 25, 2014 Report Share Posted August 25, 2014 Do not resist the Dark Side. It is your destiny, Mark and Lou. Link to comment Share on other sites More sharing options...
bciskepottery Posted August 25, 2014 Report Share Posted August 25, 2014 But you need to have a Dark Side kiln (ripped off from Facebook): Link to comment Share on other sites More sharing options...
jammy43 Posted August 28, 2014 Author Report Share Posted August 28, 2014 Jammy both of those made my short list, good choices Last body I made was C6 Clay Body - from Val Cushing: EPK Kaolin 35 Tile 6 Kaolin 15 Nepheline Syenite 23 Flint 22 XX Sagger Ball Clay 5 Bentonite 3 I subbed out tile most of tile 6 with grolleg .... I was going for more traditional ish porcelain I'm going to throw some of this tomorrow. I feel using grolleg in stoneware is bit of a waste. Grolleg definitely has a feel to it but I think you can get the same with epk and 300 silica, and slurry mixing. I have - bag I'd c&c I haven't used yet. When I do make my clays I use a slurry method. Which I'm told is superior to standard method. I even end up lowering bentonite in recipes because clay can be "too buttery". Nonetheless im still interested using the c&c. Many here say its night and day difference over other ball clays. Eg om4. #5 So I've basically given you a few of my secrets Slurry mix clay Sub out portion of 200 silca with 325. Age clay with moldy rag. Big Lou I also slurry mix and use silca 325. but I'm interested in what you mean by "age clay with a moldy rag" ? I'm thinking that you are wrapping clay in a moldy rag to get some organics in there. Link to comment Share on other sites More sharing options...
Biglou13 Posted August 28, 2014 Report Share Posted August 28, 2014 Yep, old rag It dries out I put in plastic bag , moisten then use next batch. If your's doesn't work I'd be willing to cut a piece off so you can inoculate yours....... I'm wondering if specific clays needs specific mold/s. It could all be old wives tales, but It seems to work and much faster than sitting around clean.... Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted August 29, 2014 Report Share Posted August 29, 2014 Bacteria is totally a plasticizer. A couple of tablespoons of plain yoghurt gets it going nicely in the first batch of slurry. Not too much, or it gets really ripe. After that, just mix in some reclaim with any new stuff. I'd not heard of the rag trick. Cal Link to comment Share on other sites More sharing options...
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