What Makes Glazes Mixable?

[AVPottery]

Ill admit that Amaco seems to have cornered the market on their mixable glazes.  The results are just amazing, I get that they are all cone 6 glazes and Im wondering what makes them so mixable?  I want to understand what glaze properties make them blend together so well.  Have been working towards these types of effects with my cone 10 glazes but so far have not achieved it.  I had a little luck with some really thick rutile, but otherwise not so much.  

[Mark C.]

I'm not sure of the question mostly because I have zero experience with any amaro glaze.

As far as cone 10 homemade glazes mine mix fine. You need tools like mixers and glaze measuring tools like beakers for weighing or ford cuts for flow rates or hydrometers all to measure water content and flow rates-amaro has already done this for you-so learning these skills is whats needed

When I mix glaze I weigh out 100CC and weight that to get constant results-my rutile base is 194 grams for example 

So back to the question i'm not sure what it is exactly.

[neilestrick]

Do you mean color mixing, as in you mix a green with a blue to get a blue-green?

[Marcia Selsor]

I didn't get it either. Mixable? Colors or do you mean dry powder form. If dry powder foam, it is a recipe for specific glaze that needs water. Someone else has taken the work out of buying the dry chemicals and developing the formula, weighing out the dry ingredients and shipping them to your door.

 

Marcia

[AVPottery]

Do you mean color mixing, as in you mix a green with a blue to get a blue-green?

 

For clarity ill offer a picture of Amaco glaze mixing that they offer for cone 6.  They seem to have really amazing combinations when using 2 different glazes.  They have dozens of examples like this.  I would love to understand what about these glazes makes this possible.

[Benzine]

I wouldn't say Amaco has the market cornered on this.  They simply widely publish interesting combinations they have discovered.  A lot of ceramic artists do this, but don't publish their results as publicly.  It makes sense Amaco does it.  They are trying to sell a product.

 

I use Amaco glazes in my classroom, and have students keep track of their glazes/ glaze combinations in case we find some interesting combination(s).

 

There are plenty of sites/ databases that keep track of interesting glaze combinations.  But, as I mentioned they just don't get the exposure Amaco does.

[LeeU]

My idea of horror is the studying, understanding, retention, and application of glaze chemistry. So at this point in my life, having done that enough years ago to "get it", and not being in a position to mix dry glazes or bodies (tiny space, tiny quantities, different goals), I am perfectly happy with experimenting with commercial glazes and combos thereof. Forgive me if you (AV) already know this, but some excellent book resources are W.G. Lawrence's Ceramic Science, Daniel Rhodes Clay and Glazes for the Potter, and books by current folks like John Britt and other well-known ceramic artists. Even calling Amaco and talking with a tech person may help with specific questions-I have found them -and other suppliers- to be very good at simplifying the chemistry for me to "cut to the chase" of what I want to know. (I can just see the knowledgeable experts on this forum cringing and groaning at that approach!! LOL). 

[MatthewV]

I would say it is largely marketing a property that was always present. Functional glazes will almost always play nice with each other.

 

Also putting a glaze on top of another will be very different from shaking the two together.

[oldlady]

maybe the term mixing is what is the problem here.  you really mean layering, don't you?  one glaze over another?

 

i think the layering push is an attempt by amaco to make their previously ordinary glazes look more interesting.  their advertising started with the idea that now electric kiln firing can be beautiful, just like fuel firing.   it is also a way to get enough glaze on a pot so it does not come out too thin and showing brush marks.   

[Min]

Paul Lewing posted that it's having glazes with differing silica:alumina ratios. 

 

In Topic: How To Stop Glazes From Bleeding Into One Another?

25 March 2016 - 08:41 AM

The solutions to your problem that have been proposed have all been process or physical fixes, but the root of your problem is chemical.  If you want glazes to bleed a long way into each other, they need to be very dissimilar.  Conversely, glazes that are similar will bleed into each other less.  And the key area of difference is Si:Al ratio.  If the two have ratios have difference from each other that is greater than 6 they will definitely bleed a lot.  For instance if one has a Si:/Al ratio of 5 and the other has a ratio of 12, expect a lot of bleeding.  This of course makes sense.  One is deficient in silica, the other is deficient in alumina, so the go looking for what they need in the other.

So... bottom line, if you want no bleeding at all, your best bet is color variations on the same glaze.  Doesn't matter what glaze it is.  The the only variable will be how much of a flux or refractory the colorant is in each different color variation.

 

 

I also think titania either from rutile or titanium dioxide helps.

[AVPottery]

I think I should have left Amaco out of this.  Im not asking about Amaco's marketing or how to layer glazes.  I asking about the chemical properties of the glazes.  In the case of Amaco they are two very different glazes that manage to keep their own independent properties while blending to create new ones.  It might make more sense if I were to see the glaze recipes that they have.  I know that when I mix two of my cone 10 glazes they do not mix/melt together the same way as those Amaco glazes. 

 

Are they perhaps heavier in Frits? Do they possibly use Different flux chemicals that cone 10 glazes might not use.  What is it about those glazes that might be chemically different?  Those are the questions I would like to get to.

[AVPottery]

Paul Lewing posted that it's having glazes with differing silica:alumina ratios. 

 

In Topic: How To Stop Glazes From Bleeding Into One Another?

25 March 2016 - 08:41 AM

The solutions to your problem that have been proposed have all been process or physical fixes, but the root of your problem is chemical.  If you want glazes to bleed a long way into each other, they need to be very dissimilar.  Conversely, glazes that are similar will bleed into each other less.  And the key area of difference is Si:Al ratio.  If the two have ratios have difference from each other that is greater than 6 they will definitely bleed a lot.  For instance if one has a Si:/Al ratio of 5 and the other has a ratio of 12, expect a lot of bleeding.  This of course makes sense.  One is deficient in silica, the other is deficient in alumina, so the go looking for what they need in the other.

So... bottom line, if you want no bleeding at all, your best bet is color variations on the same glaze.  Doesn't matter what glaze it is.  The the only variable will be how much of a flux or refractory the colorant is in each different color variation.

 

 

I also think titania either from rutile or titanium dioxide helps.

 

Thats an interesting read, that is definitely what im trying to get at. 

[Mark C.]

Ok I think I got it.

So the way to start is with a whole bunch of test tiles and your cone 10 glazes-you mark each tile and test one or two combos on each tile write this down on numbered  tile so you know what you did on what tile-with 10 buckets of glaze this will take a lot of tiles. Thats how We did it back in the 70s in glaze calc class.

You end up with most all the combos and you see what works-then you do it agin with your results from 1st round on a second round.

Its not fast or as easy as looking at published commercial stuff  but it effective and you learn your glazes and what can layer and look good.

Over time you build off this knowledge -thats where I am today only 40 years  down that path with most of the same glazes.

My box of tests in long ago in deep storage but thats how you get here.

[neilestrick]

You can overlap just about any two glazes and get something interesting. Amaco has been nice enough to do the testing for you. Some glazes don't play nice together, but most will. As for what they will do, it depends entirely on the formulas of the two glazes. In general, the combination will be more fluid than the original glazes, though, so you have to leave room for them to run. As you can see from the samples, color theory does not really apply, because we're dealing with chemical reactions, not pigment mixing. Also, glaze A on top of glaze B will not necessarily look the same as B on A. I have a board in my studio that shows all the double dipping combinations for all 14 class glazes, so 196 tiles.

[Joe_L]

Being a relative newcomer and working from home I'm mostly layering commercial glazes so I'm interested in the OP's question about the underlying chemistry too. Am I right in guessing the combination typically ends up with too much flux in total?

 

To my taste the Amaco samples in the pictures are too runny and don't entice me, though I know others will like it.  By experiment I've found a couple of great combinations that result in a completely new effect at the right level of fluidity & gloss without being runny - I think my successful ones are where I'm using a matt glaze for one of the components or one that's at the lower end of its firing range. Of course interactions with the body make for even more variables too! 

 

Another point is whether you are wanting to produce a completely new glaze to use over the whole surface or multiple zones showing interactions where they overlap.

 

Joe

[Callie Beller Diesel]

The OP's original question has a larger scope than I think they realize. It's kind of like asking "how do I understand all of glaze chemistry, melt physics and aesthetics all in one?" The short answer is " With a metric butt-ton of testing." The long answer is "With an even bigger metric butt-ton of testing and study."

 

If the average glaze has 5 or 6 different minerals as ingredients, each with multiple molecules that react with one another in complex ways, that's a lot of chemical reactions to try and understand. Add to that a second glaze which again is made up of 5-6 ingredients that do different things entirely together, throw in things like gravity, crystallization, phase changes and heat-work, and that is a whole lot of complicated to try and understand. Measuring the exactly-how-does-that-happen requires a lot of investigation that tends to take up a lot of time that could otherwise be used to make pots with. So potters and other ceramic artists do what Mark and Neil describe, and opt for a lot of test tile dipping to find out what happens when you add A to B. Your understanding grows over time as you work, and when you're part of a healthy community that shares their results and pools their understanding. If you want the in-depth chemical understanding from start to finish, you can opt for a ceramic engineering degree, but then you have less time to make pots.

 

And that's just the science side. One girl's "ick" glaze combo is another's "shining gem in the night" on a different surface in a different context. Aesthetics are wholly subjective, and is a set of threads a bit further down the home page.