Using oxide on bisque ware as well as over glaze

[Naomibbbb]

I want to use manganese wash on white stoneware clay after it has been bisque fired to tint the clay slightly more tan/brown and after use a clear glossy glaze and use manganese as well as other oxides on top of that glaze-  does anyone have experience or knows what would happen if oxides are applied under as well as over a glaze? Will these interact or will they not due to the glaze between? 

[Min]

Hi Naomi and welcome to the forum!

There are quite a few variables that will come into play here. We don't know what is in the clear gloss glaze nor how fluid it is. Does the manganese wash just contain manganese or are there other materials in it? Which oxides would be applied under/over it? Just like with glaze testing it would be best to do some test tiles and see what interactions occur. 

[Callie Beller Diesel]

Some of it will also depend on the recipe of the glaze. The various flux materials can have different effects on some colouring oxides. For instance, if you put a copper wash over a white clay body, a clear glaze with a lot of sodium will give a more blue turquoise. But if the main flux is boron, we’d expect it to tend more towards green. Manganese might have a more purplish tint to the brown if there’s a lot of calcium. Things like that. 

I wouldn’t expect a wash that’s over a glaze to react with a wash applied under the glaze, unless the glaze is especially thin or unless the glaze firing is especially long.