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tomhumf

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Everything posted by tomhumf

  1. I did take your previous replies on board however - I've been continuing to fire reduction with tape on burner ports, as I can't get rich yellow flames just with closing the damper. I don't know if it's my kiln design or what...but closing damper enough for yellow flames means temp starts to drop - I can't increase gas anymore at this point. I'm actually getting a little too heavy reduction though overall by reducing hard at 900C for one hour, with 4 of the burner air holes taped. I'm wondering the best option for lighter reduction. If I reduce without the tape on burners
  2. I've been struggling with this glaze for a while. Firing to cone 7-8 in reduction with speckled stoneware. I'm aiming for a silky matt smooth surface, which happens occasionally and on small test tiles. https://glazy.org/recipes/119355 The worst example shows the base of bowl, it's like the iron in the clay is poking out, surface feels almost like sandpaper. There's lots of very tiny pinhole / bubbles - not sure how you'd describe them. I seem to get better results where I think the tests were hotter ( inside of dish), but I can still see some similar surface imperfections.
  3. I made a similar kiln, not sure the thread is updated to what I do now. I use a brick on the top of chimney as my damper . I fire in oxidation, reduction then neutral. I get probably within half a cone top to bottom.
  4. @liambesaw ok thanks. Maybe I'll just run the emptier tanks on their own to start firings, and pigtail the fuller ones when I need the extra volume.
  5. They are 47kg tanks. I have a thread about my kiln, don't think it's the one you mention though, it's a 10 cubic ft internal space running on one burner. It's about 12 hours firing. Probably not half inch of ice actually, but very icy. I may be able to reduce gas usage in future, still working on my glaze schedule. I don't have a problem with icing tanks when bisque firing for 12 hours. Nobody responded to my question about if the gas would equalise between tanks if I connect them together. I've watched a couple of videos about propane valves and it seems they would work both ways, so a
  6. Hmm, they don't shut off, I just start to loose pressure. It's running at about 1.5bar in reduction. It's not just a freeze line, I get about half inch of ice building up by the time I need to switch, over half way up the tank. I thought linking them would mean half the gas used from each one so they would freeze up half as quickly.
  7. I get through quite a bit of gas firing my kiln with one burner, the tanks are freezing up while they are still half full. It's not really practical to run water on them. I think if I connect two together they will stay thawed for longer, I'm not sure the best way. I've found this connector , which I would use with my existing regulator connected after the T junction. https://www.ebay.co.uk/itm/New-LP-Propane-Gas-90Cm-2-way-Hose-Connector-Coupler-of-Two-Gas-Tanks-Acme-Nut-/264275507385?_trksid=p2349624.m46890.l49292 May be stupid question, but do the valves on top of tanks only
  8. Thanks Bill, I did try initially to reduce with just the damper. It seemed to not work very well, i.e loosing temp or blue flames from the spy holes. I'm right to think blue flames would give bad reduction? Maybe I just needed to crank the gas more or something. I did have positive pressure during the hour reduction - yellow flame from bottom peep. I can see you point about keeping above neutral for the later stage. I was a bit worried about having enough gas in this case so wanted to make sure I completed the firing.
  9. I just wanted to update this thread with my latest results. I have been using the kiln mostly just for bisque firings since I last wrote - these have been going fine. The previous glaze firings didn't turn out very well - didn't really have successful reduction. I've read a bit more and found this article really helpful http://ceramicsfieldguide.org/pdf/val-cushing-handouts/special-extras/Cushing-HighFireProcess.pdf Using that as a guide I started getting great results from my other tiny kiln. Basically oxidised to start, reducing hard @900C for around an hour, then firing in
  10. I've only been full time for around 6 months but it's going well so far. It sounds like you don't need to worry about making speed, I think I throw slower than that. Like others have said it's all the other stuff that sucks time. I start to finish about 50 pots a week, they are mostly customised so take longer to finish than plain pots. I sell everything online , for me getting my dispatch setup efficient was key. I used to spend ages sorting labels and taking everything to the post office, waiting in cues...Now I've got some dispatch software that combines my Etsy and Shopify orders in
  11. Bill - I do fire to cones and temperature, it was only hitting around 1210C with cone 7s down before. I've done two firings since posting this message. Both times I've got kiln up higher in temp - around 1230C and held for 30mins. The cones are very melted, it might be nearer cone 8 now. All pots so far have been problem free, glaze is a bit shinier, so it must just have been underfiring before I think. I do prefer the more Matt look. I may try increasing clay, reducing quartz with new firing style. I'm not sure if that might bring this problem back though.
  12. Hmm top temp could be an issue. I usually only get up to around 1210C which I know is low for cone 7, even though cones are well melted. I did hold for a half hour at top temp in this firing, and downfire to 1100. I don't fire super slow - around 8 hours so not sure why top temp is low. I bisque fire in a larger gas kiln, its about 12 hour bisque with 3 hours between 700C and 900C.
  13. Thanks, I always use the same clay and bisque fire. I fire to cone 7, but it's a little gas kiln so it could be temp differences. I guess more frit then...
  14. Hi, I wonder if someone can say if this is crawling or not? I'll post pictures in a minute. It works fine on some pots but not others. It gives little bare patches and also some bubbly bits occasionally. I'm thinking of increasing the frit or maybe thinning glaze a bit... Thanks. Blue wollastonite 9 Frit 3134
  15. Thanks everyone, lots of good advice even if it's going in different directions. I'm 39 so have a few years of making ahead hopefully so I do need to think about my body. I got a bit of wrist strain the other day after using clay which was too hard, this got me thinking again about reclaim. I certainly wont be doing 10 ton a year, probably not even 2 at this rate but would like to find a solution. I'll do a bit more research on pugmills, I've never even used one so wouldn't know what to look for in second hand one, and need to work out the different types. I can see the a
  16. I tried some tweaks to the recipe for this. In the end I've found changing the firing schedule has greatly improved the original recipe. I have added around 30mins going up between 1100C and 1200C, soak for 20mins when the cones drop, then downfire for 20mins. So around 1 hour extra I'm total. The reduction levels are around the same as before.
  17. I have recently started working full time at pottery. Beforehand my reclaim system was working ok - keep scraps until dry, add water, blitz, dry on plaster. I'm now getting a lot more reclaim to deal with and can't keep up. I plan to get some more plaster bats. Climate here is wet and cold - my studio is mostly cold too. Sometimes I put some slip on the bat to dry and it's still wet after a few days. Apart from more plaster bats, does anyone have tips for speeding this up? I've considered a pugmill but not sure that's my biggest problem - it's mainly the drying. Can a full time pot
  18. Hi All, I've mainly worked with oxides as colourants in the past but have recently been trying out some stains in glazes. I'm aware that mixing oxides does not usually work like paint mixing and usually gives unexpected results. I'm wondering if the same is true with stains? They are generally the same shade before and after firing. I have three green stains but none are the right shade I am after, I wonder if I could mix my perfect shade then fire it. I'm thinking of testing some mixes, but not sure if it will work. Thanks My stains : GS3
  19. I do start reduction around 1600, and I'm pretty happy with how my firing cycle goes at the moment for most of my work. Even this glaze turns out good 95% of the time. I think I'll just do some tests reducing the titanium then look at other options if that doesn't work. I read this on digitalfire.com , hopefully it's ok to quote : ". 6% is pushing the edge of how much titanium should be in a recipe. Any more, or cooling too slow, could transform the surface into a mass of white crystals (which would be rough and non-functional)."
  20. Hmm, I don't think it's glaze thickness. I use it on a lot of wider open items and it's fine. On the underside of plates it's ok outside footring but bad inside the footring. It is a speckled body, I don't really want to change that though. Hopefully I can tweak the glaze to fix.
  21. Hmm, not really sure. It seems to just be on the bits that are getting the least air. I'll do some tests with less titanium. I guess I could substitute some for zirc sil.
  22. Right, it's hard to see from photo but the surface on these bits is really pitted, like the glaze has been bubbling or something. Would that be due to too much reduction?
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