No Term Limits
Sep. 26th, 2014 01:39 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
offcntrStain. A ceramic colorant, formulated from metal oxides and minerals, fired and ground fine to be stable in glazes, slips or clay bodies. Major manufacturers include Mason and Cerdec-Degussa.
Refractory. Resisting melting. Alumina hydrate, a component of clay, is an example. In glazes, chrome oxide is very refractory, and will need extra fluxes to compensate.
Fluxes. Oh lord, are we gonna get into glaze chemistry? Fluxes lower the melting point of a ceramic mixture, be it clay, glaze or slip. Mostly from the alkali and alkaline earth series on the periodic table, although lead is a flux at low temperatures, and borax a flux in low and mid-range. (Okay, strictly speaking, borax is a low-temperature glass-former. I am not going there right now.)
Gerstley Borate. A naturally occurring mineral containing calcium and borate fluxes, also some silica. Used to be a common glaze material until the manufacturers announced that the mine had run out, at which point every potter in the world bought out their local suppliers to stockpile for the coming apocalypse.
At which point they announced that they'd found a five-year supply in a warehouse somewhere and surprise! it wasn't going away anytime soon. Half a dozen synthetic versions are now available along with the real thing. My base glaze used to call for 10%, but I re-calculated it using a frit instead. I still use Gerstley in overgrazes because, at a teaspoon a batch, that 150 lbs. is gonna last me well into the next millennium.
Frit. Synthetic ceramic material. Generally colorless and used to replace things like Gerstley Borate or water-soluble fluxes. Made like stains, by mixing, firing and grinding. Different frits are known by manufacturer and number. Ferro 3195 is my choice for my base glaze.
Refractory. Resisting melting. Alumina hydrate, a component of clay, is an example. In glazes, chrome oxide is very refractory, and will need extra fluxes to compensate.
Fluxes. Oh lord, are we gonna get into glaze chemistry? Fluxes lower the melting point of a ceramic mixture, be it clay, glaze or slip. Mostly from the alkali and alkaline earth series on the periodic table, although lead is a flux at low temperatures, and borax a flux in low and mid-range. (Okay, strictly speaking, borax is a low-temperature glass-former. I am not going there right now.)
Gerstley Borate. A naturally occurring mineral containing calcium and borate fluxes, also some silica. Used to be a common glaze material until the manufacturers announced that the mine had run out, at which point every potter in the world bought out their local suppliers to stockpile for the coming apocalypse.
At which point they announced that they'd found a five-year supply in a warehouse somewhere and surprise! it wasn't going away anytime soon. Half a dozen synthetic versions are now available along with the real thing. My base glaze used to call for 10%, but I re-calculated it using a frit instead. I still use Gerstley in overgrazes because, at a teaspoon a batch, that 150 lbs. is gonna last me well into the next millennium.
Frit. Synthetic ceramic material. Generally colorless and used to replace things like Gerstley Borate or water-soluble fluxes. Made like stains, by mixing, firing and grinding. Different frits are known by manufacturer and number. Ferro 3195 is my choice for my base glaze.