Using oxide washes for reglazing

[studioaptceramics]

Hi all,

I recently had some disappointing glaze results (muddy underglaze with clear). I was thinking about adding iron and/or copper oxide wash onto the glazed pieces and refiring. Would that cover over the previous glaze? I've seen a lot of advice for reglazing but less about using oxide washes. 

Thanks!

[Min]

Hi and welcome to the Forum!

If you don't like the results you have so far then there isn't really anything to loose by trying the wash. As to whether it covers the glaze, probably not but something might happen, what happens is going to be trial and error. Washes can be applied then wiped or sponged off green or bisque or they can be brushed on either on top or under a glaze. I would suggest warming the piece(s) up before trying to apply the wash. If you use a copper oxide wash overtop of a glaze it would be best not to do this on a surface that could come in contact with food.

Re your muddy underglaze colour with clear glaze, this can happen depending on the chemical composition of both the underglaze and the glaze insofar as the reactions between ingredients. For example green underglazes that use chrome (in the stains within the underglaze) will turn the green to a not so attractive brownish colour if the glaze contains zinc, chrome tin stains (for some pinks, reds and purples) will get bleached out if the glaze doesn't have really high calcium levels causing grayish tones to the underglaze. Colours can also be affected if the glaze is applied too thickly, underglaze can look milky and clouded.

Edited November 22, 2023 by Min