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tomhumf

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  1. Hmm, it's not black just fired in reduction and the lighting was bad in those photos. I guess the glaze could be having an affect... It's the clay on the image, my probe doesnt go much above 1200 so I think it should be ok in theory. https://www.valentineclays.co.uk/product/stoneware-special-fleck I'm about to fire some more with a slightly wider and further out foot ring, will see what happens with those. Thanks
  2. Thanks @Mark C. Would you think wider like thicker footring, or wider like further to the outside? These are cone 8. @Callie Beller Diesel thanks, I could try that but wouldn't that be more if the centre was slumping? If anything the centre is lifting a bit, maybe it's slumping in the centre first in the firing I guess. @Minok I'll look into that
  3. I've been struggling with this for a while. My dinner plates look fine after trimming and bisque firing. Then after the glaze firing a lot of them flop over and I get a bump on the inside around the outside of where the footing is underneath. Sorry if that doesn't make sense, I can't really get a photo of it. Basically after drying the inside is a smooth curve, but after glaze firing the inside has a bump in the curve. I throw them to 12" from 2kg of clay. After trimming they are around 0.8 - 1kg, after glaze firing they are 700 - 800g. The foot ring is trimmed to 8" at the widest point. I try and trim all areas to the same thickness. There doesn't seem to be a relation between weight and warping, even some of the thinnest ones are ok. Any ideas? Maybe more clay, wider foot ring? Photo is good one on right, flopped on left
  4. Oh thanks I didn't see duplicate. Hmm, Ok thanks. I haven't tried it on other bodies, this clay is fairly high in iron I think. I'll do that if I ever got other clay in.
  5. Hi, I stumbled on this glaze when trying various additions to my base glaze. It's very similar to a glaze I used before with titanium dioxide and copper carb as colourants. That one went green and I had assumed because of the copper carb. This glaze goes green without any copper - just rutile additions. Adding copper as well seem to have very little effect. Can anyone suggest what's causing this? Also, would you say the base colour without rutile looks like a celadon? Otherwise how would you describe it? There's some more info on the glazy page https://glazy.org/recipes/148698 Thanks!
  6. 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, just using the damper and the flames from peeps are blue will I still get some reduction? I'm thinking of reducing tape to 2 holes instead of 4 next firing - it will be quite a full load so don't want to risk having it all oxidised.
  7. 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. I'm going to try more 3134 next time, and maybe more soda feldspar and less Wollastonite in case the high calcium is a problem. It does seem like there is a lot of frit already for this cone though? Any ideas welcome please.
  8. 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.
  9. @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.
  10. 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 full tank would fill an emptier one. Can you confirm @liambesaw as you do it this way? Thanks
  11. 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.
  12. 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 work one way? If I have mismatched tanks I'd want the emptier one to run out, not get filled up by the fuller one. Would it matter that gas would be at full pressure before the T junction, or would it be better to have a regulator joined at the valve of each tank?
  13. 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.
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