Joseph Fireborn
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Posts posted by Joseph Fireborn
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Joseph, I've started making a bunch of small bud vases to test glazes on, like you do. For most of my pottery life I've been more interested in form than glazes, so now I'm in the unusual position of having to decide on pots for my glazes, rather than glazes for my pots (although I've been using terra sigillata for my large coiled pieces for a while now). I think oilspot glazes really suit the shape of Jian tea bowls, but I'd need to get myself a wheel if I wanted to do something like that.
The little vases are so great. I can't wait to see one in oilspot! I agree the Jain teabowls look so cool. I want to make one eventually and put on the oilspot super thick.
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Joseph, it's a mystery to me why I'm getting the spots, since I fire really low and slow to get to cone 4. My max temp was 1129 C, whereas the iron bubbling in traditional oilspots is only supposed to start at about 1230 C (depending who you ask). The major difference is that my glazes have boron, so that might somehow be catalysing the process, or it could be some other process happening. But the fact that glazes like the ones I'm getting are quite rare at mid-fire temps, seems to indicate that there's something about the way I fire that makes a difference. I've seen papers that mention high iron boro-silicate glasses are prone to phase-separation, but until I brush up on the necessary chemistry, I can't say if this is relevant.
Yea I have no idea. Either way whatever your doing is excellent. I am not a person who really cares to much about the purity of the chemical process. Like making something look like reduction when it was actually electric. I am not a purist in that matter. If you can get beautiful oilspots at cone 4 then who cares! Do it. Those look really nice. I can't wait to see them on a piece. Are you going to do the traditional oilspot bowl! to demonstrate it?
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Joseph, that's good to know, although ideally I'd like all the bubbles to heal in the first firing. Someone's mentioned holding the temperature on the way down to allow the holes to smooth other, but I only held at 960 C in this firing to try get some iron reds, which is probably too low for the oilspots. I know you slow down the cooling, but is this only after first dropping quickly from the top temp, or do you go slow all the way down?
Currently I drop 400F per hour from cone 6(2232F with 20minute hold) to 1750F. So I don't instantly drop, but I do drop pretty rapidly. I have tried both and I didn't seem to get different results. I have also tried the holds on the way down after dropping 100F from cone 6. However I still had the same issues. The best results were a really hot cone 7 firing, almost 8 by holding at 7 for a long duration. This gave me the smoothest surfaces. From what I understand the iron bubbling to get the oilspots starts happening right past 2250F. So I am not sure how exactly your getting these spots at cone 4, but maybe I am misunderstanding how exactly everything works. Are you firing really fast to cone 4 which enables you to reach the same temps as cone 6(usually 2232F) but not getting the equivalent heatwork?
Either way, knowing that a beautiful piece comes out with bubbles can just be refired is a nice piece of mind while experimenting with this process.
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I can attest to the thicker glaze equal bigger oil spots. I use a cone 7 oil spot that if different thicknesses bring out different sized spots. Also another thing I noticed is that if you have unhealed bubbles in your glazes as most oilspot do. You can refire and the bubbles seem to finish bubbling and you get a smoother surface.
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Darn it! I had a good bit written here but it error-ed when I tried to post it.
Pieter, I don't think anyone minds about tiles being posted in a tile thread! Looking at the results is fantastic.
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joseph, you always seem to find the neatest things online! this looks like it would be perfect to remix glaze that is in the spray bottle. i know it is a small enough diameter to fit the opening of the bottle but is it really strong enough to reconstitute a glaze that may have dried out? naturally, i would add water first and let it sit awhile before trying the machine.
I doubt it. At least the model I have. I don't think it would reconstitute well. It mixes up fluid soft glazes but if the glaze was chunky I really doubt it would do the job. There are other higher quality frothers that might have more rpm. the one I got was cheap and just right for what I wanted. I figured I would burn it up pretty quick so I went with cheap over quality. I burned up 3 immersion blenders in the last 2 years. So I am pretty rough on the things.
Remember I am just using it to mix in liquid additions of water + oxide or chemicals into an already brand new batch of glaze. You could try it for $9.99 and see, but I don't think it would.
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I just wanted to report back on my stirring problems. I finally went out to the local mall and bought a 9.99 milk frothier. It stirs the little cups perfectly and is much faster and easier then stirring the cups by hand manually.
I plan on running a lot of currie test in the coming months as I will be done with summer school and on a much easier schedule. Plan on using the addition method that I described above. So far it hasn't seemed to let me down at all. All the test I have made from the addition method have looked exactly like the grid tiles. Which means that the increment %'s that get adjusted each time are working great.
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Black clay is Sio-2 black ice.
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For purposes of looking at the grid horizontally then looking at the vertical test. The results were pretty close.
From the Yellow Ochre Tile:
5, 8, 9, 10, 14
From the Yellow Ochre and RIO Tile:
4, 9, 20
This is just for reference comparing. I don't think modifying the grid for vertical is needed now thinking further about it. We can basically deduct from the chemistry in the glaze if its going to run a lot or not. I pretty much predicted these on paper doing what they would do here. I do think I will make a new grid with a pool and ridges though as to see more variety.
The color addition method is fantastic though. I will be doing more test soon with that method. Although once you have made several test from the base like I did here, I think you pretty much can determine the tiles you like, then run line blends for different colors off a base.
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Have had this in the back of my mind for a few days, came up with something that makes me shake my head and smile. My parents.
Have had comments from them ranging from “people actually buy these?†to a remark on a speckled glaze, “oh, it looks like it has fleasâ€. Doesn’t stop there, at a market my dad came into my tent (while customers there) and said “has it been this slow all day?†Not to be outdone my mum once said, “if we pay your tuition how about going into accountingâ€.
My husband and children have always been super supportive.
So, question would be, what’s your family like?
(if you don't have one, want to borrow my parents?)
Hahaha. I love it.
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Always neat to see someone else grids. We have a lot of test fanatics here. Always post any grids you make, we love to see them!
I wish I would have been able to take a workshop from him. My favorite part of a workshop isn't learning the techniques, but obtaining the insight, views, and thought processes of the workshop host. That is usually more valuable than the actual workshop itself. I imagine his was great!
When you say re purposed grid, are you going to make a new grid blueprint? I have been thinking about it, but haven't made a new one yet.
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I am not worrying about it for a while. I am going to vertical test the grids I liked from the last tiles and just work with them for a bit. If I just test too much too relentlessly I will burn out. Learned that lesson last time. I think the grid can be improved without a lot of effort with a simple mold change. I am letting it sit in my subconscious while I work on other things.
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I was writing a reply to your first post when the second popped up!
Curt. I think the striding man is important. I am not sure why I have never used it. I did little ridges in my tile. You can't see them here, but they are there. They are only probably 1mm in height though.
I have looked extensively at your grid stuff.
I am not sure I understand your 2nd post about the rooks and stuff. I think your saying that you make a flat tile but with pegs basically? This would be great if one could figure out a way to mix and stir all 35 and dip at once, like you said industrial science lab stuff. As far as stirring I think a milk frother is going to be perfect for quick stirring for us potters.
One interesting thing about your post is it got me thinking about another way of doing what I want, but with a flat tile like you said. Although I am still not sure if it is better than taking the extra time for the vertical one.
Basically we still make a 25mm tile square. But we divide it in half. Make one half of it sloped down, with a slight indent for glaze to be placed and sit. Sort of like the melt test on digital fire. Basically we give it enough angle so that it will run slightly if fluid. The trick would be figuring out the depression so that you could put the glaze in it and then when it melts it would still run. Then have a slight gully to catch the excess so it doesn't mess with the 2nd half of the tile. Which would be the flat test with two ridges in different heights, and a slight pool.
So basically for my continued addition method you would do something like, 1 ml on one half of the tile and one ml on the other half. One half is a angled melt test, which should give you some indication of what it would look like on a verticle fired piece. Then the second half is the flat test, which is basically what we are doing now, but with less glaze since the tile is cut in half, which should make it similar to what we are already doing with the 2ml for thickness.
A person would have to spend a lot of time making the mold for this particular grid, or make one really good stamp and stamp 35 tiles each time. I think I might be getting too complex. It seems very possible to make a grid mold that would have these features, it would just take a lot of time to make the initial mold, but if done right could be worth the effort.
I am enjoying the conversation getting the juices going. I like doing the currie test. They make me understand a lot of what the ingredients are doing a lot better, but we need more detail of vertical melts.
Here is quick sketch of the idea I am not sure if this is the best explanation, but just a quick idea.
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Joel:
This is what I am thinking about making.
I am making a blueprint grid where I will have ridges(.25'' wide) instead of a depression for the horizontal row divisions. I have a handheld extruder. I will extrude .25'' strip that is long enough to span the 5 rows width. I will place a square or circle dent in those to match the squares below them. I will let that strip dry so I can pick it up without it distorting too much, then I will vinegar slip the depression that comes out on the actual grid tile and place in the strip. If I measure right it should just sit in there with the vinegar slip it should hold just fine. Let this dry and presto chango. I will have vertical and flat Currie test. Use my standard 2ml addition formula but put one ml in the top and one ml in the bottom.
Could all fail horribly. I think the C based corners are going to run right off the vertical tiles and pool in the flat one, but really I could care less, nothing useful comes from those tiles most of the time for me as I don't do much flat work. Also going to make sure I add a pool inside of my flat tile square.
If it fails, oh well I wasted a few hours making the blueprint. If it works, its 10 minutes additional work to make a grid tile, with 100% more information.
Hopefully this works as it will drastically help me explore these grid tiles and progress my glaze work a lot faster.
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I would just do the grid on the tiles, no point in duplicating it. Make 7 big L's instead of 35 small. Hit with something round to make a dint and glaze+tip sounds good.
This is interesting I like that idea. Using the same principles could do 1ml in each hole. Just need to figure out a way to catch the overflow. I like that Joel. I really do. *puts on thinking cap*
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I have no idea what is going on with the green color. I am not sure cause I have never ran a grid on this glaze before. I am assuming it is the frit+feldspars and who knows what else.
The 2% is the additions I added in via the spreadsheet. I added 2% to the base cups with Yellow Ochre, then 2% RIO. Everything I added was done via 2ml to the grid tiles and to the cups, using the math from the spreadsheet to make sure everything was even. 2ml is way too much for my tile without some type of pool and mountain to define the characteristics of the glaze better. I don't know if it is worth the effort or not but I am going to make another grid blueprint and dig a hole and also add a ridge. This way I can see pooling and breaking better. I still think we will always have to run vertical tiles of the grids we like though. Unless....
I was thinking is making an L shaped tile, then making a pool(indent) in both the top and bottom of the L. This way I get a melt test/flow test, and a pooling test. Run this along side the grid for optimal results?
I attached an example of what I am thinking. Basically lay the top of the tile, the red dot down. Fill it with 1ml of glaze. Lay it back up, let a little drizzle out. Fill yellow spot with glaze. Push up the edges of the tile base with your fingers when making the tile, creating like a little pool so that the top red glaze wouldn't flow off the tile. Could work? Still a lot of work to create 35 tiles when the majority of them would be useless. But it solves the solution of the grid being flat only. Would need these tiles to be like 1 or 2 inches wide probably to get 1ml of glaze in each pool.
I am still thinking with some real dedication you can make a better grid for testing.
I will try both things. I will make a new grid and make 35 of those tiles manually, since I don't have an L shape extruder.
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Okay. Here are the results of the incremental test I ran. I ran a base and then 2 additional tiles. I was going to do a third(6th tile total) and I was just to tired of stirring. So these are the three I did on a base glaze I plan to use often.
I am going to attach them so you can see all three side by side hopefully. They will be in the following order:
Base, Base with 2% Yellow Ochre, Base with 2% Yellow Ochre and 2% RIO.
As you can see the math works pretty well. The tiles resemble each other almost identical except for the coloring changes. I think you could easily go as far as 5 tiles deep. The biggest issue is as I said above, stirring in the bloody oxide additions and keeping the oxide addition stirred up. I am going to try a milk frother soon.
One of the problems I have with my grid is I need more detail. I am not used to putting so much glaze in a tile. 2% is definitely more than I need. I am going to create my 3rd grid blueprint tomorrow. I need something that leaves a pool inside of the grid so that I can put the majority of the glaze there, then a thinner amount on the outside of the pool, and some type of bulge to see a resemblance of the melt quickly... As for the method, it works good enough for me. Obviously I run an aggressive slow cooling schedule. My favorite tiles are 9, 14, 19. Tile 9 is exceptional in surface and in interest.
My next step will be running vertical test on the 9 total tiles that I liked in varying thicknesses.
Thoughts?
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What is your favorite part of your most favorite glaze and why?
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So I ran the addition method today. I will say I overestimated my ability to do an additional grid in 20 minutes. It was more like 40 minutes. The actual measuring and inserting into the cups was fast and easy. Mixed up the amount equalized it and then input the additions stirring the addition cup to make sure it was mixed. However when I went back to mix the addition that was squirted into the cup, I ended up spending about 40-50 seconds on each cup mixing it to make sure it was well blended. This was definitely the huge timesink. After the 3rd grid my wrist was hurting. Talking about 26 minutes of stirring per grid. So after the 4th grid I had stirred over an hour. However I was able to produce 4 grids today which is a lot more than I could usually do in an afternoon. Took about 4-5 hours total(I took several breaks for food and drink). So estimating that is like 75 minutes per grid(w/breaks). Which isn't bad at all.
I was thinking though, surely there is a small immersion blender I can buy, or even better one that is on a stand that I can just put a cup under and press go for 10-15 seconds then stop and suck out 2ml. With a rapid blender I imagine 20 seconds would be plenty of mixing time. Also this would be super helpful for the addition mix, since it is just an oxide or something in water. So it requires a lot of stirring to keep it suspended while sucking out 2ml each time.
I am going to wait and see the results of my firing on Monday and if the actual process worked even remotely good, I will look to order a stand immersion blender or what ever that is called. (wife told me, its a milkshake blender.... perfecto.)
Anyways, more updates in a few days.
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The reason it is .02 instead of .0196, is because it is rounding to 2 decimals. But yea. I think it is close enough. I mean we are still stirring and stuff so it never is going to be exact. But I think it is a good enough place to get the incremental decreases in base to add in the additions to keep the base close enough to make a discovery accurately. If we enjoy a cell we can always line blend again with a more accurate amount of say 200g or something.
Pieter, I am rusty at math, been like 9 years since I used any.. I almost got a degree in mathematics. I changed major after Calculus 3. Just wasn't enjoying it anymore. Linear algebra and combinatorial mathmatics was my favorite.
Your formula matches the numbers I got so that makes me feel confident. Thanks for that. Now to just attempt the modified method and see how it goes. Which I plan on doing this afternoon.
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Here is my quick and dirty method for getting these dry mix amounts.
Explanation:
I am holding some rules to make my life easier, you can adjust these if you want, but I want even numbers to make it easy to do efficiently.
1. I will always remove and add 2 ml of volume from the cup, then back to it with the addition.
2. I will always get equalizing volume of the additional batch by using 80ml as my point, mixing 40 cups worth. This is so that there is extra when I am down to the last few cups worth of material. This is the same with the corner mixes. The math on 40 cups mixed with 80ml volume, makes each addition a perfect 2ml for each cup.
3. By doing 1 and 2. I keep the total volume of each cup 48ml.
An explanation of the basis of my math. You only need to input the additions you want to include. The rest is done, and the dry batch for the addition that you want to mix up to 80ml equalizing volume is in the light yellow color.
I calculated the dry weight at 300g for each corner, then equalized it to 470ml. I have found almost all my test this is the usual place my A corner feels about right to base the rest of my corners off. If your using some wacky glaze, might have to change this.
An example of my process through the sheet:
- We start with an approximated dry weight of 30.64g in each cup of glaze. This is from the math by Currie in his book.
- After we remove 2ml from each cup our new base is 29.36g. Math is in the spreadsheet cell details. It is also from Currie.
- Then I take the addition I want, 2% increase each time(for this example). Say I want 4 grids after the base grid with each increasing titanium 2%.
- To calculate that I take the new base dry which is 29.36g(after I did the base grid tiles) and multiple that by 2% giving .59g. Then I multiple this by 40 cups. This gives us the dry batch size to mix of our first addition of titanium which is 23.49g (rounding stuff in the spreadsheet)
- We mix and equalize this to 80ml. Then distribute 2ml into each cup.
- Now we have our new dry amount in each cup estimated by the previous amount + our new amount from the additional 2ml. Our new total approximate dry per cup is 29.95g. Total Volume per cup is 48ml.
- Now we stir the cups and take out 2ml, and add to grid, this amount will be approximately 1.25g from the dry weight removed from the addition mix to cup. I multiply this number times my total addition percentage to get a number. Then I subtract that number from the amount removed. This is 2% of the 2% we added to the cup. Thus we can calculate how much of the base came out of the glaze. Which leaves us with the amount of base glaze we removed from the cup 1.22g. Now we take our previous base of 29.36g and subtract this amount. Giving us our new base of 28.14g in a cup of 46ml total volume.
- Repeat this process, continuing to subtract the additional % of the % as we continue adding incremental additions while decreasing the base each time.
The math for all this can be rounded, because I don't plan on sitting there weighing out 26.99 instead of 27, or 28.14 instead of 28. I am just trying to get as close to accurate results as possible. This should work pretty well imo, as we are adjusting the amount of base glaze each time for the new additions.
Spreadsheet: https://docs.google.com/spreadsheets/d/1faETrVYo0Lin_2LU7GYK2BgvOuVLf3cCpefjQzRC5ns/edit#gid=0
I tried to explain my thoughts the best I can. My son is singing songs and playing games beside me, so no telling if I made a mistake in my typing, however I believe my math is correct.
It appears the removal of the base does make enough of an impact to warrant adjusting for it. * the more you know theme song.*
Anyways. I know this is a lot of hoopla to most everyone. However I am going to give it a shot tomorrow and I will fire probably Sunday night. I am going to do incremental additions of iron oxide.
I am hoping with the addition of this method I can have 5 grid tiles in around 3 hours. I have the other process down to about 2 hours. So I am giving myself 20 each minutes for the other 4 grids. This is a huge boon to the earlier 2 hours spent on this. Also a lot more results to look at for the initial 2 hour investment.
All said and done you could just ball park it and just do a line blend later. But if your going to do all the effort might as well get as close as you can. The dry batch mixes make more of a difference in number when you increase the amount added to say like 5% per addition. Then you start going up 2-3 whole grams!! lol.
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Exactly man. This is what I am building now. I am almost done. I have to run to my supplier to get some cone packs. Want to make sure the schedule I am going to use is firing to exactly where I want.
You have what I am saying exactly in your head the way I am thinking. You remove the amount the first time for the base grid. Then you recalculate dry inside of the wet. Add % increase. place all the test again. recalculate new base again. repeat for as long as you think is accurate for the base decreasing each time at a 4% decrease per test if using 2ml as your mark for tile.
Beginning wheel throwing projects
in Studio Operations and Making Work
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I'll throw the shapes and take pictures just to see where I am at in this. I think my cylinders are still not the best. I have a hard time getting the very bottom of the walls even. I will try this next time I am in the studio.
Interesting stuff pres.