mansie131 Posted May 8, 2017 Report Share Posted May 8, 2017 Hi, i'm having trouble with iron oxide slip applied at the greenware stage. i've noticed that a thin layer gives varied colours and a thick layer gives either black or nothing- does it burn off? (i use a transparent glaze over this) additionally, a lot of the colour washes out on cleaning after bisque. what's going wrong and how can i stablize the slip to give me a solid black? i use stoneware fired to cone 09 bisque and cone 6 glaze. thanks! Link to comment Share on other sites More sharing options...
Benzine Posted May 8, 2017 Report Share Posted May 8, 2017 Hmmmm.... What color of iron? I've only tried black iron oxide, but had no issue getting it to be black...ish... More of a dark grey, but still nice. Are you using the iron oxide, you'd add to glaze recipes, or a mason stain? I've noticed that some of the black mason stains note that the zinc in them will lead to more brownish colors, than black. Also, I had a black iron oxide, that would turn greenish, when covered with Amaco's Clear Transparent. Link to comment Share on other sites More sharing options...
neilestrick Posted May 8, 2017 Report Share Posted May 8, 2017 What percentage of iron is in your slip? Link to comment Share on other sites More sharing options...
oldlady Posted May 8, 2017 Report Share Posted May 8, 2017 are you using your clay slurry from throwing plus the iron oxide or are you following some recipe with lots of ingredients? or are you actually making a wash with just the iron and water? Link to comment Share on other sites More sharing options...
mansie131 Posted May 18, 2017 Author Report Share Posted May 18, 2017 Hi all, i'm using clay slurry + 40% RIO Link to comment Share on other sites More sharing options...
Marcia Selsor Posted May 18, 2017 Report Share Posted May 18, 2017 That seems to be an extremely high percentage of iron. Where did you get that recipe? I think you should lower the percentage to 10% or less and add a small amount of flux to your slurry. Marcia Link to comment Share on other sites More sharing options...
curt Posted May 19, 2017 Report Share Posted May 19, 2017 And test! Link to comment Share on other sites More sharing options...
neilestrick Posted May 19, 2017 Report Share Posted May 19, 2017 Firing at cone 6 you may need as much as 20% by dry weight, and it will probably need 2-3 coats to get it to show evenly. Link to comment Share on other sites More sharing options...
Benzine Posted May 19, 2017 Report Share Posted May 19, 2017 I spoke too soon with my slip. Put a clear over the pieces I used it on, and it turned a dark brown. I still like how it looks, especially on a piece where I did a sodium silicate crackle. Link to comment Share on other sites More sharing options...
Charles Posted November 14, 2018 Report Share Posted November 14, 2018 My school only does one or two soda firings a semester, but I just saw this and really like the look - based on the foot it's a ~ dark tan -light brown clay. Wondering if this is likely achieved with a low percentage of RIO or something else? thanks Link to comment Share on other sites More sharing options...
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