[Borax again]

On 1/19/2023 at 8:45 AM, Callie Beller Diesel said:

We don’t like borax, but we love boron. Most sources of boron are bucket soluble to some degree or other, but borax is particularly bad for it. When the material is that soluble in the bucket, it affects the viscosity of your glaze how it applies.

Picture this. You mix your borax based glaze and use some of it that day. It works great, your pots turn out fantastic, so you make a bigger batch before you make your next round of pots. While you’re spending 2 weeks (or more) making your next kiln load, the borax has a chance to dissolve in the glaze water. Next glaze day, your bucket looks like it’s thickened up a LOT. If your glaze gels and you do nothing, it goes on too thick and can run or cause crawling. You fire a kiln load of this ware, and you then have a bunch of shelves to clean. Plus, you’re out the work you spent 2 weeks (or more) making.  If you add water to your glaze to  make it flow properly, but for some reason your floating blue now is more of a yucky brackish brown colour. Again, you’re out the pots. Frustrating, but you’re a potter, so you’re undaunted! You then head to the internet and learn about how water content affects your glaze outcome, and you realize that the amount of water in the first batch was correct, but the  rheology or flow that was a problem. Now you have to start adjusting your glaze’s rheology with deflocculants like darvan (sodium silicate can and will make it worse). 

The material is cheap, but you pay more in time trying to fix problems and in wasted work. It’s more economic to use other sources of boron like gerstley borate or frits.  Many boron frits are still soluble, but a lot less than borax.

That said, if you’re knocking together something like raku glazes that will be used the same day,  borax could be a a good teaching material. 

Just stir in some darvan or Epsom salts to deflocculate or flocculate the glaze if its too thick or thin. Its easy and quick.