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Joseph Fireborn

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Posts posted by Joseph Fireborn

  1. 34 minutes ago, Pieter Mostert said:

    Reduction makes iron a more powerful flux, so if the same is true for copper, that would explain why the SiC tiles appear more fluxed. But I don't know if this is the case.

    I totally agree on this point. I know iron is a flux in reduction, but I am not sure that this is the case with copper. I have never read that anywhere, but I don't fire reduction so again I could be wrong. But it doesn't account for the crazing improving slightly as more SiC is added. That would be opposite factor I would assume? 

  2. 2 minutes ago, Pres said:

    Ron, I realized that, just pointing out that for some the need to do things differently is important. I haven't had a full cookie since 2009. 

    We stopped eating gluten, as it was tearing our stomachs up and making me and my wife ache. We didn't realize it but over the last 30 years we have developed a sensitivity to gluten. We have cut it out completely and feel much better. It is hard to do. I agree the apples look better with the pie crust deliciousness, but there is no way I could eat that now. 

    I might make an apple baker. It looks interesting to throw and we love apples. Yum. I had forgot about this post. I need to throw the bowls and cut them in half too.


  3. @curt I agree with most of that, with some exceptions:

    - The picture might not show it but there is little red specks in each of the high flux tiles, that said they are nothing like the red appearing in the right corner as you said. I personally like the red dots on the crazed surface. I actually have plans to use that as it is such a rare thing to see, a blueish green glaze with red specks. Very pretty. 

    - I thought SiC was refractory.  It would require some good flow test to actually prove that it is "fluxing" the glaze. I might be up for that eventually but I have some other plans to work on. That being said I don't really understand either how the surfaces are better on the SiC tile. I also did .4 and .8 SiC as well I just didn't post them. They have the same increasing properties. As SiC increases between the tiles the cells get smoother and smoother. The red from the oxygen theft isn't that much more apparent when increasing the SiC by 100% each time. It would be interesting to preform a flow test with something like 0% SiC 1% 2% 3% 4% just to see if in fact it is refractory at some point but some other chemical process is happening that is causing the glaze to "flow" or "glass" better. The smoothing of the cells definitely happens as I increase SiC. Looking at tiles .4, .8 and 1.2 you can literally see the smoothing effect happening  when looking at all three in order. I will attach .4 and .8 below.  

    - The pictures don't show it well, but the crazing is slightly decreasing in the SiC tiles, as would be expected as you are increasing the ratio of silica to flux. (I will try to add a better picture that shows the crazing.)

    I will start posting pictures hosted via my webserver instead of the upload in the future, because it is hard to make assumptions like the ones we have made with crappy resolution pictures. Sorry about that.

    My theory is that the smoothness comes from the Silica in the SiC. I think it is balancing the alumina and silica ratios ever so slightly so that the glaze is more stable. But this is just a theory. All the right hand rows, even though some are smoother look underfired to me.  The reason I believe this is because the only corner that doesn't seem to care about the SiC is corner D, and the tiles around it. It looks pretty much the same from every tile. 




    Crazing Picture: I cropped the close up pictures. As you can see the SiC is actually reducing the crazing, which makes sense considering it is comprized of mostly silica right? I hosted this one on my webserver so you can click it a few times to get to the actual source and see it in higher res.


  4. I broke it in half on the tile I was talking about earlier. It definitely has places that look like bubbles. I don't have a microscope camera so the picture is pointless, but when I hold up a magnifying glass to it, it has bubbles below the surface. But still, do I care about those bubbles? I mean the surface is still smooth isn't that the goal for the work? Although I could care less about those tiles on the right hand side. The best tiles are 16,17 and 21. I am actually going to develop those glazes further I think and add more SiC. I think it could handle upwards of 2-3% SiC cause at 1.2 it shows 0 signs of bubbling and very little red dotting. But this is going to be for a later time. I have another glaze I am about to spend a few months documenting thoroughly. 

  5. Quote

    The problem is I cant seem to control when the pinholes come and when they dont.  For instance, i make pie dishes some glazes will come out perfect other will be covered in pinholes, but only on the outside.  

    It is interesting they are only on the outside. 

    We had a discussion a few months ago with brandy lee.

    She was having pinhole problems, she adjusted her hold from 20 to 16 to 10 minutes and got rid of the pinholes,but she also added a downdraft vent. Maybe try decreasing your hold since only the outside stuff is pinholed. Isn't usually the inside of pots cooler because of the radiant heat? Maybe the outside is getting overfired and is causing miniblisters?

    I am not real sure just going from others experience. 

  6. @Benzine No plans to name it. If anything I might use it on some vases or something, but I doubt it is safe for using for food. Considering it has 30% Iron Oxide in it. lol. I have to presume it will change the flavor of the food drastically. I just glaze two cups with it, and that is probably the last I will ever use it. I need to focus on one thing and explore it deeply. I probably wont be doing anymore currie grids for a few months.


    As promised here are the results from the currie grid test of the copper sic glaze: (left is base, right is 1.2% SiC).


    My favorite is grid 11. The greenish blue with red specks is very nice. I would say that my most favorite is 16, but it crazes slightly. 17 also has some merit.

    I changed the recipe from the original in johns book. I didn't have enough Frit 3110, so I went with 3134, which lowered the SiO2 amount drastically. Which I was ok with since I wanted the lower bounds of the limit. However I think it might have overfluxed. I don't know. Anyways. 

  7. Well. I finished my spreadsheet.

    If anyone wants to use it because the currie sheet is all bonker: https://docs.google.com/spreadsheets/d/1faETrVYo0Lin_2LU7GYK2BgvOuVLf3cCpefjQzRC5ns/edit?usp=sharing

    The green areas are the place you input data. There is no complicated rules for entering data. Just put in the amount of flux directly from your recipe in grams, same for colorants. I couldn't think of any recipe with over 6 fluxes I have ever used, so I just went with 6. 

    I have also included my addition method in case anyone wants to use it. I use it so I incorporated it here. 

    Once you put in your data, click to the spreadsheet on the bottom called: Currie PrintOut. It will have all your information there. Just print it. Done.

    My copper SiC tiles are cooking. I will post the tiles tomorrow. Let's hope the Alumina Silica stuff holds true again.

  8. I dont understand where the book gets its numbers from. He list a bunch of percents for the grid tiles, then later the math he provides doesn't match at all with those percents. It's rather odd.

    For example the limestone set.

    He list 70 Feldspar 30 Whiting.

    For glaze 1. The amount of Flux Materials should be: 60%. Thus feldspar: 60% * 70 = 42.00, whiting: 60% * 30 = 18.00. This is what the book list. Then the very next glaze is out of wack.

    For glaze 2. The amount of Flux Materials should be 54%. Thus feldspar: 54% * 70 = 37.80, whiting: 54% * 30 = 16.20. But the book has: 37.63, and 16.13. How in the world is he doing his math? Makes 0 sense.

    Even his Kaolin/Silica numbers don't make sense. It is like he didn't stick to the basis that he posted on page 32 which has the % kaolin, silica and flux materials for each grid. Somehow he moves off those numbers slightly?

    I have been just using these numbers assuming they are correct. But it doesn't appear to be so unless I am missing something here. 

    I mean I guess it doesn't matter much since they are just decimals off, but still I don't like puzzles. I also noticed several of his grids don't add up to 100%.... on page 32. Grid 28,13 and 7.

    Edit: Now I think I see is going on. way to make some things really complicated by not just showing % + decimal. meh....

  9. @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.

  10. @High Bridge Pottery 


    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? 

  11. 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!


    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:



    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. 

  12. 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. 



  13. 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. 

  14. 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.



  15. 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:


    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. 


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


    Another set of tiles with drastic color and surface difference:


    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)


  16. 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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