Borax

[Judy Schnabel]

I've been corresponding with a friend of mine who is new to fusing and is having problems with devit or some type of haze. He's been viewing posts on our board and learned of Borax. Personally, I don't care for Borax as it seems to leave my glass blotchy so I prefer Super Spray. Be that as it may, this is what he wrote me recently:

"I was wondering how this (Borax) worked chemically and therefore have done some research. I found that borax is basically a hydrated form of powdered glass. When it is heated the water is driven off and a borax glass is left behind. This looks just like regular glass, BUT! Here's the glitch. This glass is very unstable. It will eventually re-hydrate and therefore loose its shine (it will wash off eventually)! This can occur rapidly or slowly depending on its environment! My question is this: What is super spray made from? If it is just a borax solution and anything
it is used on will exibit the same characteristics as my borax mix!

In other words, will it wash off? Can't find anything on this."

Any comments from the scientific types -- Tony, Ron, Bert, Brad?

Judy

[Cynthia]

...not one of the science guys, but here's how I understand it. Don't take it as gospel. You can get a better understanding of what devit is, what fluxes are and what an overspray is (sort of) from many glass forming books. Chas. Bray's book Dictionary of Glass is a good one among others.

Borax like lead is a flux and acts in a chemical fashion with the glass. It lowers the melting point, so the borax treated surface is melting at lower process temps and doesn't form the random crystal structures that are devitrified glass. The crystals form a chaotic pattern vs the lattice type formation of undevitrified glass. This random crystal formation is unstable but typically in fused glass it's only on the surface, so isn't too problematic in terms of stability...it's just unsightly (unless you figured out how to make it happen on purpose) This is probably not an accurate scientific description...but it's how I understand it. The science guys will have to correct any misinformation I may have provided.

SuperSpray is comprised of ground glass suspended in a soln. of alcohol and some other substance to remove the surface tension, a surfactant like a sticker spreader for gardening (don't know what that substance is, but nonetheless...). The way SuperSpray works is sort of like adding a clear cap to the glass. That's why it's so shiny and perhaps why you like the results you get better than the results you get from borax.

[Judy Schnabel]

Cynthia,

What do you think of the statement that it (Borax) will wear off eventually?

Judy

[Tony Serviente]

My experience with Borax is that it weathers poorly. After one upstate winter outdoors the surface deteriorates, but I have Borax treated surfaces that have lived indoors for 14 years that still look nice and glossy. I don't know if it's the temperature changes or the exposure to moisture that does it (though I suspect it's a combination). Wonder if anyone out there in a warmer but wet clime has a story to tell of Borax in the great outdoors.

[Bert Weiss]

Cynthia,

What do you think of the statement that it (Borax) will wear off eventually?

Judy

I've wondered about this. My understanding is that borax is a water soluble glass former. I made a set of sushi plates that are used daily in a commercial dishwasher. After 2 years they look a bit scratched but otherwise good. I was worried about what would happen if the borax wore off. My conclusion is that beneath the borax is shiny glass so there is not a problem.

[Brock]

I've wondered about this. My understanding is that borax is a water soluble glass former. I made a set of sushi plates that are used daily in a commercial dishwasher. After 2 years they look a bit scratched but otherwise good. I was worried about what would happen if the borax wore off. My conclusion is that beneath the borax is shiny glass so there is not a problem. Bert \

Hmmm . . . that isn't true of some overglazes, I'm not sure about Borax.

[Ron Coleman]

Here is an interesting discussion from several years ago about borax.

http://www.warmglass.com/cgi-bin/wgarch ... read=53157

Where is Hugo these days?

Ron

[Bert Weiss]

I've wondered about this. My understanding is that borax is a water soluble glass former. I made a set of sushi plates that are used daily in a commercial dishwasher. After 2 years they look a bit scratched but otherwise good. I was worried about what would happen if the borax wore off. My conclusion is that beneath the borax is shiny glass so there is not a problem. Bert \

Hmmm . . . that isn't true of some overglazes, I'm not sure about Borax.

What do you mean about what isn't true? Turn of the century enamels were made with borax as part of the formula. Those enamels disappeared in part, or whole, on interior stained glass windows. Today enamels are formulated to last (no borax). That would be true of overglazes like spray A, which is essentially a clear enamel.

The factor I still wonder about is what does the surface look like after a coating has dissolved. I didn't notice any weird scum on my plates.

BTW I only did one batch of my sushi plates with the borax. I was using some salvage 3/16" glass stacked up. That glass tends to devit so I used borax. I now only use 3/8" which doesn't devit so I don't need borax.

[Brock]

I've wondered about this. My understanding is that borax is a water soluble glass former. I made a set of sushi plates that are used daily in a commercial dishwasher. After 2 years they look a bit scratched but otherwise good. I was worried about what would happen if the borax wore off. My conclusion is that beneath the borax is shiny glass so there is not a problem. Bert \

Hmmm . . . that isn't true of some overglazes, I'm not sure about Borax.

What do you mean about what isn't true? Turn of the century enamels were made with borax as part of the formula. Those enamels disappeared in part, or whole, on interior stained glass windows. Today enamels are formulated to last (no borax). That would be true of overglazes like spray A, which is essentially a clear enamel.

The factor I still wonder about is what does the surface look like after a coating has dissolved. I didn't notice any weird scum on my plates.

BTW I only did one batch of my sushi plates with the borax. I was using some salvage 3/16" glass stacked up. That glass tends to devit so I used borax. I now only use 3/8" which doesn't devit so I don't need borax.

What I meant was, it's my understanding that overglazes do not STOP devit, they MASK it. In other words, the devit occurs whether or not you spply asn overglaze, but if you do apply one, the devit is not noticeable.

How a clear layer of glass (overglaze) hides devit is beyond me, but I have noticed, (in those very few cases where I've had devit, harumph, harumph) that it is the texture, or surface matting that is noticeable, and somehow the clear overglaze hides this effect. Brock

[Cynthia]

Cynthia,

What do you think of the statement that it (Borax) will wear off eventually?

Judy

I don't have a clue about it wearing off, but this is what my intuition tells me.

My understanding is...

Borax is a flux (overspray), not an overglaze and is an agent that is causing the glass to be liquid at lower temps and to stay liquid longer. It acts upon, or interacts with the glass rather than coating it with another glass, therefore preventing devit by allowing the glass to maintain it's appropriate ordered matrix.

What Brock states about overglazes not preventing devit but masking it makes some sense to me. I've certainly used Superspray to hide devit and it often works. But perhaps it can also prevent it by creating a barrier (new layer of glass) between the environment in the kiln and the base glass. Devitrification after all is occuring only on the surface and not deep into the body of the glass in kiln fired pieces. An overglaze is simply a new, different layer of glass wether it's an enamel or Superspray (which might contain an enamel for all I know) or whatever...so that makes sense that they would or could be fugitive as a very thin layer/coating of new glass.

My thinking about a flux is that it wouldn't wear off. It may be that it changes the nature of the glass enough to make it softer or more vulnerable to etching than it would be without an overglaze or overspray? But you can wear down the surface of any glass with exposure to the elements...salts, acid rains, erosion from wind and the like...knives and forks and scrubbies.

Just thinking outloud, I don't really know the structure of changes of the glass before and after firing with overglazes or from the effects of fluxing agents...

[Brian and Jenny Blanthorn]

Cynthia,

What do you think of the statement that it (Borax) will wear off eventually?

Judy

I don't have a clue about it wearing off, but this is what my intuition tells me.

My understanding is...

Borax is a flux (overspray), not an overglaze and is an agent that is causing the glass to be liquid at lower temps and to stay liquid longer. It acts upon, or interacts with the glass rather than coating it with another glass, therefore preventing devit by allowing the glass to maintain it's appropriate ordered matrix.

What Brock states about overglazes not preventing devit but masking it makes some sense to me. I've certainly used Superspray to hide devit and it often works. But perhaps it can also prevent it by creating a barrier (new layer of glass) between the environment in the kiln and the base glass. Devitrification after all is occuring only on the surface and not deep into the body of the glass in kiln fired pieces. An overglaze is simply a new, different layer of glass wether it's an enamel or Superspray (which might contain an enamel for all I know) or whatever...so that makes sense that they would or could be fugitive as a very thin layer/coating of new glass.

My thinking about a flux is that it wouldn't wear off. It may be that it changes the nature of the glass enough to make it softer or more vulnerable to etching than it would be without an overglaze or overspray? But you can wear down the surface of any glass with exposure to the elements...salts, acid rains, erosion from wind and the like...knives and forks and scrubbies.

Just thinking outloud, I don't really know the structure of changes of the glass before and after firing with overglazes or from the effects of fluxing agents...

Devit is glass molecules arranged in ordely fashion micro cristaline or larger cristals or both

In our normal glass the molecules R arranged in a random manner ( with some glasses this is not true )

Anti devit stuff works by making the glass 2 liquid so the cristal cant grow, also it will tend 2 disolve any neucleation points, so again it cant grow

Devit will only grow within a certain viscosity range

To stiff or 2 liquid n it cant grow

It aslso needs something 2 grow from like dirt or a scratch ( neucleation point )

It is this reason that devit usually only grows at an interface

Anty devit applied 2 light devit will mask it as it will B shiny n there may B a little disolving going on depending on temps

Brian