Borax again

[Gonen]

I found this seller talks about the wonderful benefits of borax to ceramics glaze : 

Benefits of Borax: 

For glazes and enamels, boric oxide is unique in that it acts simultaneously as a glass former, as a flux, and as a viscosity stabilizer that prevents the glaze from running too much while it is being fired. Perhaps most important of all, boric oxide reduces the thermal expansion of the glaze so that it can be matched to the expansion of the underlying ceramic or metallic body. At the same time, it improves aqueous and chemical durability while adding to the brilliance of the glaze.

https://www.ceramic-glazes.com/borax-sodium-tetraborate

when people that use it say it has many problems in cone 6 ox glaze .....  and why the fact its water soluble makes it problematic for glaze ? wouldn't that suspends evenly and better in the glaze ?    

any experience or good recipe you do have ?  for its really cheap and has boron and sodium 

thanks 

 

[Dick White]

The problem with solubles in a glaze slurry is that the dissolved flux materials (e.g., borax, soda ash, sodium leaching out of neph sye or some frits) moves into the interior of the bisqued ceramic with the water as the glaze is applied. Then it stays there. Because it is a flux, the ceramic body is fluxed (and thus overmelts), not the glaze. It you want to use a soluble material in a glaze, you have to use the glaze right away, before it has a chance to fully dissolve into the water, or used it in a specific way, such as carbon trap shino, where the migration of the dissolved sodium creates the desired effect.

[Callie Beller Diesel]

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. 

[Hulk]

Borax variants - looks like they are high in sodium.
Adjusting the oxide mix to eliminate crazing was an adventure for me - less sodium, less potassium, more magnesium, a very small amount of lithium...

Nepheline Syenite is likely the highest sodium ingredient in my Studio.
I don't see that changing. I've been "set" with glazes for a few years now, and although I do plan to break out into new territory in terms of color, finish, movement, et cetera, I'm not looking to get into new materials ...unless I have to.

Borax could very well be useful in pottery. I'm curious to know who is using it, why, and for what.

[Kelly in AK]

I’m borax curious too, about a couple things. One is anhydrous borax, it’s borax fired to glass then reground. The other is using borax in a soda/salt firing. US Borax has a fact sheet on it but I’ve never seen anyone do it.

https://www.borax.com/BoraxCorp/media/Borax-Main/Resources/Technical-Bulletin/borates-salt-glazing.pdf?ext=.pdf

[neilestrick]

3 hours ago, Kelly in AK said:

I’m borax curious too, about a couple things. One is anhydrous borax, it’s borax fired to glass then reground. The other is using borax in a soda/salt firing. US Borax has a fact sheet on it but I’ve never seen anyone do it.

https://www.borax.com/BoraxCorp/media/Borax-Main/Resources/Technical-Bulletin/borates-salt-glazing.pdf?ext=.pdf

Interesting. It makes sense. It would be interesting to try. Maybe I can convince some folks I know to try it.

[Min]

Looks like the solubility of anhydrous borax in room temp water is 2.7 g/100 ml vs borax at 6.3 g/100ml so it's about half as soluble. Couldn't find solubility numbers for frits to compare with. 

[Shark]

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. 

[Callie Beller Diesel]

@Shark Easy is subjective. I personally have no problems adjusting glaze flow, but we’ve also heard from lots of folks who feel otherwise.

Adjusting glaze flow does take practice and it can be easy to mess it up, especially if there’s a lot of different solubles working on the glaze slurry. While the conversation here started going towards more processed materials, the OP specifically referenced a very soluble form of household borax. It can take very little material to accidentally over-deflocculate a glaze and turn it into a completely congealed and unusable mess. And then your materials savings are gone, because you have to throw out the batch.