Ceramic slip mixture

Oct 30, 2005 2 Replies

I own my own ceramic shop and I recently was given more info on mixes of ceramic slip. I was told that adding barium to the mix makes it whiter. BUT I also know that barium is poisonous. Does this make it dangerous in the dry form when cleaning or firing? Any replies would be helpful. Thanks.


Small amounts of Barium added to slip or clay prevent scumming, and are relatively harmless as the chemical effect in clay is different to that in glaze. Barium in glazes is generally NOT food safe. I suggest you increase the opacifier in the slip (if there is one). If there isn't add up to 10 percent Zirconium Silicate. You may have to re- calculate the amount of deflocculent in the slip though, as a result. Tin Oxide or Zirconium are routinely added to decorative slips to make them whiter, but Tin is more expensive. Titanium Dioxide is also used, but it is more of a creamy colour than a white.

Steve Bath UK

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