Glass frit in glaze

[Lucy GReen]

Hi, 

So I really want to create an effect like the one below using glass frit as this is what is used within in glaze in the image. However I can't work out how it works technically as glass obviously melts around 800-900 but I will want to fire to stoneware at 1260ish... Surely the frit will melt down the side rather than just bloom? Or does the glaze suspend it? 

Many thanks

 

[Bill Kielb]

Is it your belief that the blue dots were created by adding bits of blue glass to the glaze? Frit  to me are very specific set of manufactured compounds used by industry with very specific properties often used to substitute for mined materials because they are formulated and uniform as opposed to natural materials which change slightly or the formulation provides special opportunities often not easily available with mined materials. Some folks call these ceramic frit’s and they generally have properties such as a fired coefficient of expansion compatible with fired ceramics 

Glass however does not have these properties so combining glass and ceramics most often ends up in failure and something that is not durable for use.

Have you contacted the person who made the mug above? It actually might be a lowfire claybody with a lowfire decorative glaze. There are several that have similar results.  Amaco Crystaltex has similar blooming properties. Generally these glazes are only used for sculpture work though.

[Lucy GReen]

  Hi! Thanks for the reply. 

So I contacted the seller and she said it was a glaze with small bits of glass in. 

I really want to create this affect myself using a transparent glaze with added elements rather than buying a glaze as the ones I've seen aren't the affect I want to achieve... Even if I went for an earthenware it's still far too high for glass. However I  really want to get this affect on white stoneware and I've been researching for ages but I've got no answers.  I don't want the affects of a crystalline glaze. Is there any way of adding glass that would affective? 

Many thanks

 

[Roberta12]

@Lucy GReen  I really does look to me like the amaco crystalline glazes.  Perhaps the person just thought it had little pieces of glass in the glaze?  I have messed a little with glass pieces in the past and they would simply run and also make your piece not food safe.  I found this....

Amaco Crystaltex Glazes | BLICK Art Materials (dickblick.com)

Roberta

[Bill Kielb]

I think You likely could recreate this effect with ordinary underglazes. Glass and ceramics just aren’t compatible IMO.

Edited January 5, 2021 by Bill Kielb

[Callie Beller Diesel]

If she used glass in her clay, it’s ill advised on her part. I know it doesn’t stop some people if they don’t see anything going wrong immediately, but that doesn’t make it a good idea. The coe of bottle glass or other commonly available glasses including stains and frits used in a hot shop are too distant from that of most pottery clays. I’ve gone on clay/glass rants before. I don’t know that the internet needs another one.

If you want a similar effect, you could try mixing a clear blue glaze as a paste, crumble it and fire the bits just enough so they sinter. This will keep them from dissolving when you add them to another clear or translucent glaze bucket. They should melt together for a similar effect. The Jungle Jems line does something similar I believe. 

 

 

[Hulk]

All glass aren't same, methinks; frits are glass, but may not behave same as bits of a soda bottle, as not made of same stuff. Our glazes may be called glass as well, and we see they are formulated to melt at various cones, etc. - different.

[Lucy GReen]

I'd never thought of sintering glaze! Thank you so much

[Callie Beller Diesel]

2 minutes ago, Hulk said:

All glass aren't same, methinks;

They sure aren’t! Glaze isn’t quite the same as glass either, although it shares some ingredients. It’s like the difference between bread and cake. There’s some ingredient crossover and you need to bake (fire) them both, but techniques and times that work for a crusty sourdough will do something awful to a chocolate sponge. 

[Tamas]

Greg Daly in his book  Glazes and Glazing Techniques  mention that crushed windows glass (cullet) can be considered a frit, and says "It is similar to borosilicate in  its fluxing ability,, but with a different colour response from iron, giving olive greens, brown and blacks, and a strong copper response under reduction." But obviously this is not to achieve the effect Lucy is looking for, but interesting nevertheless.

[Hulk]

me hungry now

[Callie Beller Diesel]

I think using cullet made from window glass as a a frit in a glaze is one of those things that is possible in a realm of infinite possibilities, but could be more trouble than it’s worth if you’re trying to build a glaze for functional use. Since the OP is referencing a mug, that’s what I’m assuming we’re after. Float (window) glass has less alumina and silica than bottle glass does, and contains lots of sodium from a couple of sources which are germane for refining bubbles out, but not ceramic purposes. It’s also got lime, so some calcium and magnesium. There’s no boron in it, so I’m not sure how it’d act as a borosilicate frit. (For borosilicate, you’d need older Pyrex, or lab glass). You’d have to do a lot of testing to fine tune window glass cullet in a recipe, given you don’t know the exact proportions of the materials used. Plus, it’s a LOT of hot, sweaty work in a respirator to pound it into powder. The COE of window glass is approximately 8.4. Ceramic glazes tend to be somewhere in the 6-7 range, depending. If you’ve got chunks of glass in a glaze as in the picture the OP provided, they’re going to pull away from each other, creating stress fractures in the work.  I bet that mug in the example picture weeps if they used window or bottle glass. Or even some of the colouring stuff sold for use in a glassblowing studio.

If we’re talking about a sculptural effect, go right ahead and do whatever wild and whacky thing that makes your experiment hungry heart happy. Science is cool. 

[Rey]

Hello, I have done ceramic painting for a few years. Recently I became aware of using frit on the ceramic pieces and i loved it.  Unfortunately, i could only get a couple of bisque pieces that had the channels and concavities to pool the melted frit.  I have searched many places and i cant find any bisque stock (like dragonflies, crosses, etc.)  Do you have any leads on sellers of such stock ?  thanks

[Roberta12]

@Rey  Duncan carries bisqueware.    Is this what you are looking for?

https://www.buyduncan.com/bisque-duncan

[Chilly]

Be aware that mixing glass and ceramics can cause the glass to explode free at any time from the day after glazing, up to several months later. 

In short they are not compatible.

[PeterH]

From the archives

 

[ATauer]

So in glass fusing we have frits too, they are nothing like ceramic frits but are simply clear and colored various sizes of crushed glass that have been sieve to a specific size, they are extremely commonly used in glass fusing for decoration of various kinds. It is my guess that the mug the original poster is referencing used some of those frits in the glaze, not crushed bottle glass. You can get the frits in several different COES made by a variety of companies and out of different kinds of glass. As someone who was a glass sculptor long before I entered the ceramic world, there are definitely ways you can use glass on the outside of nonfunctional work. For example, Steven Branfman (and myself- although I do it differently) throws the beginning of a vase, takes it off the wheel being careful not to touch the outside with his hands, and rolls the vase in various sizes and colors of glass he has smashed up (I’m pretty sure he just collects a variety of recycled glass but tends to manage to find a good number of brightly colored ones)  then puts it back on the wheel and continues throwing, manipulating only from the inside and carefully widening and enlarging the vase from the inside so he doesn’t touch or cut himself on any of the glass. He lets it dry like normal, then applies a clear raku glaze, and raku fires it, and they look gorgeous. The thing is, since I’m doing research on adding glass to claybodies, they can surprisingly when mixed with ceramics and glazes act quite refractory, instead of melting at the low temperature you would assume they would. I have pages and pages of research on this. The raku glaze actually helps act as a flux with the glass and they melt a lot like the pic the OP put up, although from what I’ve seen and my experience usually the glass forms longer bursts of colors that, depending on the size of the glass chunk that started as, can be about 1 cm long sometimes. 

I’m a handbuilder, so I can’t quite do it the way Branfman does. But since I’m a glass sculpture, I often have tons of scraps left over and when a fusing doesn’t turn out how I’d like and I can’t sell it, I reuse it by smashing it up with a hammer into bits of glass I can use on my ceramics. I’m solidly anti melting sheet glass or marbles in the bottom of your bowls, or putting marbles on platters to melt etc, I’ve gotten in huge fights with people about this. They are inherently more dangerous than this method because they are much larger pieces of glass that could thermal shock at any time and fragment off and cut someone. So as a handbuilder I make bottles, vases, jars, vessels of various kinds, out of slabs, that I wait until they are just able to stand on their own then roll in the bits of glass, sometimes with some CMC mixed in to help them adhere just at this stage, then when the vessel is leatherhard I manipulate the inside so it forms the shape I want, sometimes using a paddle to help get it were I want it, since a paddle is not going to be hurt by the glass nor leave marks. I let it dry then put on various raku glazes- sometimes just a clear so the glass colors are the complete focus, sometimes I might not have enough color in the glass and will use some colored raku glazes over the glass or as accents around the piece. I fire it in my raku kiln to cone 06 and they turn out very nicely indeed! The raku glaze fluxes the glass, and also merges/melts with the glass, so they do appear to all become on one mass of glass on my wares, and I have never had a chip or anything break off or any problems at all. Maybe because the raku glaze is so low fire the glass and the glaze manage to fit together better and melt into each other,  I’m also not using recycled glass of unknown provenance, I am using Bullseye soda lime glass with a COE of 90, whereas bottled glass tends to be quite a bit more refractory. 

So these are to examples where it works- Steven Branfman has been doing this since I think the ‘80s and I’m pretty sure would have stopped by now if he was having problems with it. I have not been doing it that long because I was just being born then, but it has been working well so far and provides some interesting texture and colors that crystal glazes etc cannot emulate at all. But both these examples are raku, and our OP wants to fire at cone 6, right? Well I would suggest if she pursues this still that she not use mixed recycled glass, but instead finds a local glass artist and buys some of their scraps, so all the glass is the same COE etc and is made of the same ingredients which can prevent many issues. I would probably recommend she consider putting it on something other than a mug that would be used, or at the very least since it sounds like it is for a special friend makes sure that they know it is a decorative mug only and not to be drunk from. It should under no circumstances be put in the dishwasher or microwave. As someone who straddles these two mediums, I have been researching and hoping to eventually find my way into a Phd to research ways to incorporate both ceramics and glass in sculptures, and not just as two separate cast items epoxied together etc but hopefully find a way to make thes two materials work together better…we do know they can do something’s together, and the research I inherited from someone shocked me because in his quest to try and make a self-glazing clay body by mixing large amounts of ground of recycled glass into the clay, he found the more glass he put in the higher he had to actually fire the clay and it would sometimes be so refractory that the clay wouldn’t even flux and mature at cone 10. And sometimes it would melt into a pile of mush…which is how I ended up with this data to do something with because I thought what we needed to do was not use random unknown glass but test specific kinds of glass, most people have no idea how many different kinds of glass there are, just being used for art, let alone everything else. And unfortunately endless seeming stay in the hospital has kept me from starting to do different experiments and come up with a plan of how I want to attack this research, but he found out some really interesting things that I think are going to result in us knowing some very different things about glass and ceramics and hopefully how they might be able to be used together in various ways. It just will take time and patience but I’m assured we will get there. 

[Callie Beller Diesel]

In everything in clay, there are exceptions that prove the rule. If someone has said “you can’t!” I can guarantee there is someone out there who took that as a dare, and went and did it. But you don’t tell beginners like the OP that it’s common practice, or a good idea to do without a lot of caveats.

 It’s important to note Steve Branfman isn’t making functional items, whereas the OP was, and that’s a significant distinction. No one is putting flowers in a Steve Branfman vase. I’ve been tailoring my answers to the OP and their reference, or others who might be in a similar boat.

It’s my opinion that beginners, like the OP,  should not be using glass and ceramic together at all, IF they want pieces to last. Learn about the materials first! There’s a lot. If you want to learn through experimentation, cool! If you like science and chemistry, more power to you! Keep the results for your own reference though, and don’t give them away or sell them. If you have some skill in either ceramics or glass and want to start heading into more advanced territory by combining them, you already know there’s caveats to everything and probably aren’t getting a lot out of this thread.

I’d advise against most people using Series 90 or 96 stained glass, or products from hot shop  suppliers in ceramic applications, as well as  recycled stuff. Bullseye is great stuff for kiln formed glass or copper foil/lead came, but it’s even farther off the COE values of most commercial ceramic products. Plus, a lot of it will alter in colour when fired above kiln-formed glass temperatures, or for too long. Bisque temperatures will kill dichroic effects, as well as many pinks/ purples, and some reds/yellows/oranges. Depends on the colourants used to make it. Glass processes use a wider variety of colourants than ceramicists do, largely due to how we use heat differently.

 

Edited July 19, 2022 by Callie Beller Diesel
Finished the random half finished sentence.