ronfire Posted September 27, 2015 Report Share Posted September 27, 2015 I am using Plainsman M340 buff clay with the stoneware ^6 glaze. The problem I have is the bigger pieces are coming out milky and not clear while the smaller pieces are fine. This especially shows on the black underglaze. I am dipping the glaze. Is my glaze applied too thick on these larger pieces ( I pour in the glaze for the larger pieces) or is it a heat issue. The kiln has a sitter, fire to cone 6 then 10 min off and 30 min with the kiln set to medium for some soak time. My best guess is that the glaze was to thick. Will refire to cone 6 help? Thanks for any advise. Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted September 27, 2015 Report Share Posted September 27, 2015 Is it too thick? Probably. Will refining help? You're out nothing to try. I've been using that clear glaze over m390 all summer, and I can say that application matters very much. The specific gravity and having a gelled glaze (as recommended by Plainsman) makes a big difference in this instance. If you don't flocculate this one, it shows every drip. http://plainsmanclays.com/index.php?menupath=62 Link to comment Share on other sites More sharing options...
Benzine Posted September 28, 2015 Report Share Posted September 28, 2015 In my experience, when a clear is applied too thick, it becomes more translucent, rather than transparent. The only other time I've had a clear become milky, is when the container got mistakenly mixed with opaque white, as they look the same unfired. Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted September 28, 2015 Report Share Posted September 28, 2015 Ben, this particular glaze is weird like that. It's meant for use over a white firing body or a stoneware. The cloudy only becomes apparent over a dark clay or underglaze. The base glaze they recommend to go over darker colours is somewhat amber. Link to comment Share on other sites More sharing options...
bciskepottery Posted September 28, 2015 Report Share Posted September 28, 2015 The cloudy only becomes apparent over a dark clay or underglaze. The base glaze they recommend to go over darker colours is somewhat amber. Likely due to the ingredients in the clear glaze interacting/melting with red iron oxide and other colorants that are used in red or dark clay, an interaction you don't get in white clay bodies. Link to comment Share on other sites More sharing options...
Judith B Posted September 28, 2015 Report Share Posted September 28, 2015 In my experience, a clear glaze can be milky if it has been underfired. Maybe your bigger pieces didn't reach the correct temperature? Link to comment Share on other sites More sharing options...
ronfire Posted September 28, 2015 Author Report Share Posted September 28, 2015 I don't think the piece was underfed as the kln ran on high for an hour longer because of the heavy load. Think I will try to retire the pice and see, can't loose. Also will thin down my glaze and purchase a drip cup to get an accurate reading of viscosity. Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted September 28, 2015 Report Share Posted September 28, 2015 Viscosity is only half the key, and is the less important half in this instance. If the specific gravity is off, it affects how much glaze material is deposited on the pot when the bisque absorbs the water from the mix. You can affect the viscosity with vinegar or Epsom salts once the s.g. Is correct, so that the glaze stays suspended in the bucket and you don't have to re stir it every 3 seconds because everything settles out. You can check the specific gravity by calibrating a clear plastic drink cup on your scale. Weigh out 100g of water, mark the bottom of the meniscus, empty the cup and dry. Next, fill the cup with glaze to the line, and weigh. Divide that number by100, and there it is. (And base 10 math is cool!) Link to comment Share on other sites More sharing options...
Mark C. Posted September 28, 2015 Report Share Posted September 28, 2015 Scotty more heat is needed-full power warp speed is needed. Mark Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted September 28, 2015 Report Share Posted September 28, 2015 The cloudy only becomes apparent over a dark clay or underglaze. The base glaze they recommend to go over darker colours is somewhat amber. Likely due to the ingredients in the clear glaze interacting/melting with red iron oxide and other colorants that are used in red or dark clay, an interaction you don't get in white clay bodies.Nah, the recommended base is kind of amber over the white clay too. Link to comment Share on other sites More sharing options...
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