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Tomorrow I am going to run my most adventurous Currie addition method so far. I am going to do a base plus 6 additions. Totaling 7 tiles. I will record the total time from start to finish. Now that I have this milk frother I am really hoping I can cut each tile down to like 20 minutes after the base is made.

I am looking for an iron based black semimatte glaze. So I am taking a iron red based semimatte glaze and running a currie on it, then I am going to do my addition method 4 times adding 3% iron oxide each time. The recipe already has 12% iron in it, so my additions will take it to 15%, 18%, 21%, 24%. I figure this should start showing me where the glaze becomes black and over saturated. Then I am going to test SiC at .4% and .8% to see what SiC does as the ratios of silica and alumina vary on the grid. Plus I am just curious to see what happens to 24% iron oxide with SiC! lol. I am hoping maybe I get a magical discovery somewhere in there. 

On a side note I assume their are limits to the amount of iron oxide one should put in a glaze, but I figure why stop at 18% when discovery is always a possibility. 

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1 hour ago, Joseph F said:

Tomorrow I am going to run my most adventurous Currie addition method so far. I am going to do a base plus 6 additions. Totaling 7 tiles. I will record the total time from start to finish. Now that I have this milk frother I am really hoping I can cut each tile down to like 20 minutes after the base is made.

I am looking for an iron based black semimatte glaze. So I am taking a iron red based semimatte glaze and running a currie on it, then I am going to do my addition method 4 times adding 3% iron oxide each time. The recipe already has 12% iron in it, so my additions will take it to 15%, 18%, 21%, 24%. I figure this should start showing me where the glaze becomes black and over saturated. Then I am going to test SiC at .4% and .8% to see what SiC does as the ratios of silica and alumina vary on the grid. Plus I am just curious to see what happens to 24% iron oxide with SiC! lol. I am hoping maybe I get a magical discovery somewhere in there. 

On a side note I assume their are limits to the amount of iron oxide one should put in a glaze, but I figure why stop at 18% when discovery is always a possibility. 

When you run your Currie test do you mix up a big batch of base glaze and take what you need as you go or do you mix up several 100g batches?

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8 hours ago, BlackDogPottery said:

When you run your Currie test do you mix up a big batch of base glaze and take what you need as you go or do you mix up several 100g batches?

I have done this when there's one glaze you want to run a lot of tests with. Mix up a big bucket to 1.5sg and then take out 240ml~ for each corner glaze. As long as you can measure the volume and it's well mixed I think it is accurate enough.

(Weight of glaze - Volume of glaze) x (5/3) = Dry glaze  :   (360 - 240)x(5/3) = 200g dry glaze 

I use these numbers to get down to 75ml corner glaze instead and 25ml spare for when I mess something up.

medium.FullSizeRender.jpg.b5de4cf8cb5e2f

 

Edited by High Bridge Pottery
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I made some confirmationish discoveries with my currie grid test in results to SiC. I have said it before but I sort confirmed it today. 

I have said in the past that glazes that have more flux seem to do better with the bubbling issue in regards to SiC. I ran some grid test this weekend and I did the vertical results yesterday and pulled them out today. I have nice smooth surfaces that are definitely different than their non-chemically reduced pairings. 

What I have found so far, again limited testing with only a few glaze combinations(I am going to try a copper reduced currie test soon to confirm this more), is that as the silica and alumina ratio increases in relationship to the fluxes decreasing your glazes start to bubble. It also appears(again not confirming yet), that as the ratio starts to enter into the .25(alumina) & 2.50(silica) the bubbling seems to be relentless. Some of the grids don't look bubbled, but if you hold them at an angle you can see it just didn't break through the surface. The only results with surfaces perfectly flat were ones where the alumina and silica ratios were below .25 and 2.50. 

This has a few important meanings. Depending on which limit formulas you observe your working with glazes bordering on the lower limits. This might bother some people more than others. I will always still test durability as such for any glaze. The limits to me are more like guidelines than hard rules. I don't mind skirting on the lower end of them, particularly if it can lead to entirely new discoveries with glazes in oxidation.

I am curious if anyone else has ran these types of test on SiC. I am really interested in it, but I have to balance the testing and production of work so I can't dive directly into it, but I am going to try to continuously run some grid test each week with SiC.  

And just to show the differences in some of my tiles. Click the pictures for better view. 

This was the best tile I removed:

IMG_20171106_124605.jpg.c8d60af700ba2058ca18384c394473ce.jpg

The same tile compared to its non SiC brother. Left(SiC) Right(normal). The left tile has more a satin surface chemically produced. The glaze is exactly the same and was fired side by side in the kiln. The right tile is drastically more glossy. Which is interesting I don't really understand the relationship with how SiC can reduce the surface to a semimatte. Although I have to say i enjoy the semimatte surface much more. The tile on the right is classic iron red stuff, but the one on the left is very different. 

IMG_20171106_125520.jpg.52128f9c3ce658f21842e0a976a1b90a.jpg

The most drastic comparison of two tiles with again left being SiC, right not having SiC:

IMG_20171106_133239.jpg.e469738b4d5fefa3c71028367301594e.jpg

Another set of tiles with drastic color and surface difference:

UUWm4TK.jpg

In general it seems that with iron oxide the SiC has a more semimatte surface and more visual interest and a variety of differences in color with very small changes in %'s of flux, alumina and silica.

Just thought I would post this here as we had some SiC discussions in the past. Thought some of you might find this interesting. The copper results will be much more visually evident. I am going to run the same glaze I did before through currie with incremental increase of SiC by .25% each time. Starting at .25 and going to 1. Just to see how long it will go before the ratios that I listed above no longer hold true. This is all new to me. So I could be way off.

EDIT: Also for those of you who are interested in how the milk frother worked out for mixing the cups. Check it out: (pwnage)
 

 

Edited by Joseph F
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10 minutes ago, Benzine said:

That tile in the first photo is awesome!  What "color" is that?

It is an iron red glaze. I am not really sure what color it is. Depending on the light it changes drastically. It can be pink, yellowish, red, orange. Of course on a tile things can be very misleading. The next step is to mix up a slightly larger batch and dip a small cup and spray a larger one. I was waiting to pickup my son and I took the tile with me to look at in the daylight.  I am not  sure if I like the glaze or not yet. Once I spray and dip on more I will know.

It really is hard to show the colors. Its reddish black in a dark room, but like this in the cloudy sun. The main thing I want to think about is the difference between the SiC and the non SiC. Really wild.

IMG_20171106_145750.jpg.50aa48cf18debc80e3c84f4bbec5b074.jpg

IMG_20171106_145709.jpg.a59ba7b0134de776feb8ac5687641a29.jpg

Edited by Joseph F
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Just now, Sputty said:

Interesting. But 'Attack of the Pirates' was better.

lol.. did it auto play that? hahah :ph34r:

That is part of my focus on my son to get him into creation instead of consumption. I spend a lot of time with him helping him discover things that he might be interested in. It takes a lot of effort, but I would rather spend time on him making things like this or art, then watching youtube videos. of course the kicker is he wanted to upload it to youtube to share with his friends. lol. 

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The glaze has .8% SiC. I don't know much about it. I have just read all the articles I could find on it, almost all of them deal with using it for either crater glazes or copper red oxidation glazes. But I am not really interested in either of those. Although I plan to run another currie(copper) just to see the green in the glaze since I don't know what exactly the SiC is doing in this relationship besides matting the surface slightly. 

 

 

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11 hours ago, Joseph F said:

I made some confirmationish discoveries with my currie grid test in results to SiC. I have said it before but I sort confirmed it today. 

I have said in the past that glazes that have more flux seem to do better with the bubbling issue in regards to SiC. I ran some grid test this weekend and I did the vertical results yesterday and pulled them out today. I have nice smooth surfaces that are definitely different than their non-chemically reduced pairings. 

What I have found so far, again limited testing with only a few glaze combinations(I am going to try a copper reduced currie test soon to confirm this more), is that as the silica and alumina ratio increases in relationship to the fluxes decreasing your glazes start to bubble. It also appears(again not confirming yet), that as the ratio starts to enter into the .25(alumina) & 2.50(silica) the bubbling seems to be relentless. Some of the grids don't look bubbled, but if you hold them at an angle you can see it just didn't break through the surface. The only results with surfaces perfectly flat were ones where the alumina and silica ratios were below .25 and 2.50. 

This has a few important meanings. Depending on which limit formulas you observe your working with glazes bordering on the lower limits. This might bother some people more than others. I will always still test durability as such for any glaze. The limits to me are more like guidelines than hard rules. I don't mind skirting on the lower end of them, particularly if it can lead to entirely new discoveries with glazes in oxidation.

I am curious if anyone else has ran these types of test on SiC. I am really interested in it, but I have to balance the testing and production of work so I can't dive directly into it, but I am going to try to continuously run some grid test each week with SiC.  

And just to show the differences in some of my tiles. Click the pictures for better view. 

This was the best tile I removed:

IMG_20171106_124605.jpg.c8d60af700ba2058ca18384c394473ce.jpg

The same tile compared to its non SiC brother. Left(SiC) Right(normal). The left tile has more a satin surface chemically produced. The glaze is exactly the same and was fired side by side in the kiln. The right tile is drastically more glossy. Which is interesting I don't really understand the relationship with how SiC can reduce the surface to a semimatte. Although I have to say i enjoy the semimatte surface much more. The tile on the right is classic iron red stuff, but the one on the left is very different. 

IMG_20171106_125520.jpg.52128f9c3ce658f21842e0a976a1b90a.jpg

The most drastic comparison of two tiles with again left being SiC, right not having SiC:

IMG_20171106_133239.jpg.e469738b4d5fefa3c71028367301594e.jpg

Another set of tiles with drastic color and surface difference:

UUWm4TK.jpg

In general it seems that with iron oxide the SiC has a more semimatte surface and more visual interest and a variety of differences in color with very small changes in %'s of flux, alumina and silica.

Just thought I would post this here as we had some SiC discussions in the past. Thought some of you might find this interesting. The copper results will be much more visually evident. I am going to run the same glaze I did before through currie with incremental increase of SiC by .25% each time. Starting at .25 and going to 1. Just to see how long it will go before the ratios that I listed above no longer hold true. This is all new to me. So I could be way off.

EDIT: Also for those of you who are interested in how the milk frother worked out for mixing the cups. Check it out: (pwnage)
 

 

Great work, Joseph, very interesting.  And some very rich glaze surfaces there.  Thanks for sharing.

A few thoughts:

First, would you be able to share photos of one or two of the actual currie grids you did for this?

Also, in the side by side samples, are you saying these two glazes are identical except for one has silicon carbide and one does not?

Regarding the bubbles issue, since you are starting to get a feel for the actual critical alumina and silica levels in your testing, I would be interested in your thought/comments on a thread started by High Bridge called "Bubble, Bubble, Toil and Trouble..." about a year ago (? you may remember it) where we had an extensive discussion about silica and bubbles based on some tests High Bridge shared.  Do your recent results shed any more light on the bubbles issue?  Are they in line with the outcomes in Joel's tests?  

Seems like you are highlighting .25 and 2.5 molar on alumina and silica as an important threshold.  Could it be that the "limits" are more context specific to certain industrial  conditions (ie, specific glaze mixtures, specific clay bodies, specific firing procedures) than we are aware, and hence not necessarily applicable to many glazes we look at?   I guess for a decorative glaze like yours maybe the limits are kind of irrelevant anyway. 

I had a quick look for some papers on the silicon carbide iron eutectic point.  Seems that molten iron (and also cobalt and nickel) is an excellent solvent for silicon carbide, starting at temperatures well below the stoneware maturing range.  Maybe the iron-heavy glaze mixture is simply decomposing the silicon carbide early and often, preventing it from delivering the usual cratering?  And, giving it that nice smooth satin matte texture.

Milk frother seems to work excellent!

 

 

 

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6 hours ago, curt said:

Great work, Joseph, very interesting.  And some very rich glaze surfaces there.  Thanks for sharing.

A few thoughts:

First, would you be able to share photos of one or two of the actual currie grids you did for this?

Also, in the side by side samples, are you saying these two glazes are identical except for one has silicon carbide and one does not?

Regarding the bubbles issue, since you are starting to get a feel for the actual critical alumina and silica levels in your testing, I would be interested in your thought/comments on a thread started by High Bridge called "Bubble, Bubble, Toil and Trouble..." about a year ago (? you may remember it) where we had an extensive discussion about silica and bubbles based on some tests High Bridge shared.  Do your recent results shed any more light on the bubbles issue?  Are they in line with the outcomes in Joel's tests?  

Seems like you are highlighting .25 and 2.5 molar on alumina and silica as an important threshold.  Could it be that the "limits" are more context specific to certain industrial  conditions (ie, specific glaze mixtures, specific clay bodies, specific firing procedures) than we are aware, and hence not necessarily applicable to many glazes we look at?   I guess for a decorative glaze like yours maybe the limits are kind of irrelevant anyway. 

I had a quick look for some papers on the silicon carbide iron eutectic point.  Seems that molten iron (and also cobalt and nickel) is an excellent solvent for silicon carbide, starting at temperatures well below the stoneware maturing range.  Maybe the iron-heavy glaze mixture is simply decomposing the silicon carbide early and often, preventing it from delivering the usual cratering?  And, giving it that nice smooth satin matte texture.

Milk frother seems to work excellent!

@curt

Let me be clear. I am not confident in anything I said, which is why I said "confirmationish". These are just the early stages of what I think seems to be true. I also read several peoples documents on SiC last night after thinking about this stuff and a lot of them seemed to notice the same thing. Even Tom Coleman's Cone 9 Oxidation recipe in his article skirts these borders with 2.67 SiO2 and .25Al2O3. So looking at my grid recipes that I pulled, all the ones I was able to use were the ones that hovered around these levels the rest had bubbling issues.

The side by side examples yes, the only thing different is the SiC. The rest of the recipe is exactly the same. 

As far as Joel's thread. I don't know how this relates to his stuff. I am not a huge chemistry buff. I can follow recipes, look at the numbers in insight, and make visual observations. As far as trying to determine what is happening chemically, I really have no clue. I am not super interested in the chemistry, more in the results. I know that the chemistry might help me obtain my results faster or understand them better, but I don't have the time to invest in it. I am finishing my degree, a full time dad, and trying to learn as much as I can about pottery in any free time I have. I will say that if Joel's test noticed that he started getting more bubbles around those same alumina and silica points then yea, maybe that has something to do with it?

The limit stuff was just an observation. I use Roy-Hesselbeth as my "guidelines" for what is a good glaze recipe. They peg SiO2 between 2.5-4 as acceptable, and Al203 as .25-.5. Thus I think these glazes where the SiC doesn't bubble is right at their lower bound limits. This could be a complete "coincidence" or it could have some meaning. I have no idea if that is true or not. I am simply reporting my observations for you much smarter people to hopefully make some conclusions. = )

I am going to run a copper SiC test soon. I have 4 porcelain grids available that I can use. I am going to mix one with the copper recipe with no SiC. Then 3 more with .4, .8 and 1.2 SiC using my incremental method. We will better be able to see on those as we know the direct effect of SiC on copper and that it should go red. This I think will be more visually appealing then the iron results, which is mostly all bubbling but the bottom left corners of 6x6. 

@Pieter Mostert

I would join that group, but I don't have a facebook. I looked at those recipes though. Her tiles seem to be rather beautiful in color, but really lacking in surface, which is the main thing I am focused on. I had some pretty decent results with Copper Red(artificial, pg 103) in Britt's book before. Although my surfaces still had some slight pinholing from the SiC. I think that this grid test I am doing today should find a better version maybe? I am really love the power of the currie test to instantly find a better version of a glaze for your particular needs. That is mostly what I use it for. Any new recipe I pick up and try 100G batch of, if it has potential I then mix a currie grid of it to find if I can find a better version. Tiles from before:

post-63346-0-30745700-1495221637.jpg

 

On a different note, someone just updated Ian Currie's website and it's terrible. The calculator page is horrible. Looks like I am going to be remaking that in google spreadsheets soon. Yuck. 

Edited by Joseph F
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That's a lot less % than I was thinking, seems to make a noticeable change.

@curt I feel it matches up with what I am noticing in general, more flux and less SiO2/Al2O3 is good for removing bubbles. Looking at the glaze I ran that had no visible bubbles it has 2.45 SiO2 and 0.34 Al2O3, also 0.18 B2O3

I think limit formula are looked at wrong a lot of the time, I see that a glaze with the lower limits is just as good as a glaze in the higher limits, it's more about ratio than boundary lines. A little while back Matt Katz was showing me Stull charts. Using that to compare my good glazes that are bubble freeish they all sit right on the corner of the white before the crazing area. If you follow that line it pretty much sits on the limit formula. I am not sure how anybody gets to the highest gloss area bubble free.

Anyway I think my point is keeping the right ratio while dropping below the limits is more important than being in the limits.

STULL_Chart.png

 

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@High Bridge Pottery 

Quote

Anyway I think my point is keeping the right ratio while dropping below the limits is more important than being in the limits.

This is pretty much how I feel. I am not sure how others feel. There are so many different limits too. Like in Britt's book, he uses the Matrix software limits which are slightly larger than Roy/Hesselbeth. In fact the tile I posted that I liked so much is in fact inside of those limits. 

I wonder what exactly is happening that we are both seeing less bubbles getting frozen in the glaze. I also wonder if this applies to oilspots as well. Could we use this same information to keep the oilspot surfaces from having those dimples? 

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@Laurène Ashley

RIO isn't increased for each tile. It was increased for each grid. I started with the base of 12% using orange street. It also contained 6% yellow iron oxide. 

So I made 8 grids total. A base with the original recipe, then I increased the RIO by 3%. So 12 15 18 21 24. These were the 5 RIO grids. Then I mixed .4% SiC into the last mix, which I then applied to grid 6. Then I added .4% more SiC and added it to grid 7. Grid 8 was just the same thing as grid 7 on porcelain(for color and clarity surface purposes).

Total time from start to finish was 4 hours for the 8 grids. Although I got much faster near the end as I started to master the process of mixing with my left hand and removing and adding glaze with my right. The tile that I posted is the 24% RIO and 6% Yellow Iron Oxide. The natural RIO would probably be a brown color.

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4 hours ago, Joseph F said:

On a different note, someone just updated Ian Currie's website and it's terrible. The calculator page is horrible. Looks like I am going to be remaking that in google spreadsheets soon. Yuck. 

There's a nicer online Currie grid calculator here, made by Tom Demeranville. The only downside is you're restricted to 4 fluxes.

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I have a sheet that goes up to 6 'flux', would be nice to add a few more just in case but I never got round to it. Also calculates 7by5 and 5by5 grids. Copy/edit away. It doesn't actually work really well for doing them in typical currie grid style but good for picking 4 corner glazes of whatever and working out each square.

 

https://docs.google.com/spreadsheets/d/11H0rugHScuaFXK1mg8xG_NJjIAUI33g3HBtsObT1AB0/edit?usp=sharing

 

 

Edited by High Bridge Pottery
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