C.Hartman Posted November 24, 2014 Report Share Posted November 24, 2014 Hello! First time posting on this forum. Using "Mastering Cone 6 Glazes" as a reference I recently did some glaze tests. Basically mixed up one base glaze and experimented with oxides in various combinations/ proportions. I picked a couple that I liked most and decided to make a big batch. One has lots of iron oxide and a little titanium dioxide and the other has a little cobalt and a little rutile. I have found that this base glaze works best when applied thin so I was adjusting the amount of water in the iron containing glaze until I thought it looked good ( dipping a shard of bisque ware). It took a bit more water than I was expecting to get to what looked like a good stopping point. Since the cobalt containing glaze is exactly the same except for the colorants I figured it would require the same amount of water. They are in the same size bucket so I just brought it up to level with the iron glaze. To my surprise the cobalt containing glaze is now way way way too watered down. Any idea what is going on here? Link to comment Share on other sites More sharing options...
neilestrick Posted November 24, 2014 Report Share Posted November 24, 2014 Adding lots of iron oxide vs. a small percentage of cobalt means you'll have more dry material in the batch, and therefore will need more water. Plus red iron oxide tends to be less pure than other oxides, and has a measurable percentage of clay in it, which will take in more water. Link to comment Share on other sites More sharing options...
C.Hartman Posted November 24, 2014 Author Report Share Posted November 24, 2014 Thanks Neil! That is helpful. I was a little mistaken... the 2 glazes actually have similar amounts of dry ingredients. The amounts of each colorant are as follows: 750 grams rutile + 125 grams cobalt carbonate, and 750 grams red iron oxide + 250 grams titanium dioxide. Wound you think that the difference in thickness is explained by the clay in the red iron oxide? Link to comment Share on other sites More sharing options...
Tyler Miller Posted November 24, 2014 Report Share Posted November 24, 2014 Unless I'm mistaken, red iron oxide can be a gelling agent in some glaze formulations. I had a tenmoku recipe a while back that would thicken like instant pudding if you let it sit, but if you vigorously stirred and sieved it, it would thin out again. Link to comment Share on other sites More sharing options...
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