Jump to content

Bill Kielb

Members
  • Posts

    3,387
  • Joined

  • Last visited

Everything posted by Bill Kielb

  1. Sorry, saw this and forgot. Condensation …… so the thing to know is when warm moist air hits something cooler than the dew point temperature it condenses on the cool surface. Sort of like condensation on a cold glass on a hot humid summer day. So for a tin shed where the steel cools more quickly than the air, generally the inside surface is insulated to keep it from getting cool enough (dew point temperature) and a vapor barrier is installed in front of the insulation. The vapor barrier is intended to ensure no water vapor can creep through the insulation and condense on the cold steel behind it. Many types of rigid insulation can be their own vapor barrier as well usually requiring taped seems. Anyway, the basics are vapor barrier always warm side, insulation, then the cold surface. Hope that helps.
  2. The Norman kilns have been traditionally table top in the 48 and 33 series. Popular for jewelry, paint, small clay. You might ask for a picture of the equipment and the kiln equipment tag first and check what temperature it will fire to.
  3. Line blends for colorant work for most, progressing from light to dark so one test can generate many shades from one small sample. Hey don’t forget mason stains.
  4. These posts are from 2020 so you want want to DM the original poster. As far as on target a glaze fire can go more like 6-8 hours or about 450 degrees per hour with the last 200 degrees of the firing at about 110 degrees per hour. So for the Bartlett V6cf cone six fast firing, likely 6-8 hours. As your elements wear your kiln will not be able to keep up and your glaze firing times will grow towards that 16 hours you seem to be at.
  5. Just a couple observations FYI - Clay goes through quartz inversion up and down. For a glaze firing if your load has stopped let’s say within 300 degrees or more of its firing cone temperature then little heatwork was likely done so refiring generally is not an issue. For bisque you can bisque fire pretty much as many times as needed within reason. Finally to make your cone drop at the temperature advertised on the cone chart, fire at the appropriate speed per the chart for the last 200 degrees. So for cone 6, center column (108 degrees per hour) fire to 2232 Starting at 2032. If you can fire per the chart, you stand a good chance at nailing your cone. Holds at top temperature can cause issues, do them only when you have a real confirmed reason to.. Bisque firing only sinters the clay together so not much melting. Bisque firing generally take longer to burn everything out so time at temperature is important. Many bisque firings range from 10-12 hours just to be sure to remove all organics. Quartz inversion just happens, up and down. Clay is tough, it generally can take it. Not much we can do about it. Typical glaze fire speeds 400-500 degrees per hour Typical Bisque speeds approximately 200 degrees per hour Hope that gives you some ideas for future use.
  6. Stroke and coat is advertised as such and I have used it for overlays, etc…successfully to cone 6 it has been around for many years. Google Mayco stroke and coat.
  7. Maybe someone with direct experience will answer but since this is a commercial glaze we have no idea of how much clay it might contain and if it is naturally deflocculated due to sodium. I suggest a good read for this https://suemcleodceramics.com/how-to-fix-a-hard-panned-glaze-with-epsom-salts/ You likely will end up using Epsom salt a little at a time to re suspend the glaze. Since bentonite can generally be added up to 2%, you might settle on 1% addition because you will never know the actual clay content, then flocculate with minimal Epsom salt as a start. Hopefully someone has direct experience with this commercial glaze for a tried and true solution. Actually a call into Amaco probably gets you the most tried and true solution for this glaze. I am sure they have seen it before.
  8. Not likely, the bend matches the radius of the motor pivot. Tensioners are usually only meant to set the tension, then the remaining bolts of the assembly are tightened so it doesn’t wobble or move removing the angular load from the tensioner. I would suggest: Check the condition of the belt, proper belt alignment (belt running true between the drive and driven pulley), and tension on the belt. Then, check all remaining bolts are appropriately tight so the motor assembly does not wobble.
  9. If you look at the label (equipment tag) posted above it appears Gare mentions directly what the maximum firing cone and temperature is for that particular model. 3 rd line from the bottom. You may find your label tells you the kiln max firing temp, as well, read all the way through it is easy to miss embedded text.
  10. You need an ohm meter and there are several videos on testing elements. All work done with Power off. Not a bad thing to own and be able to do simple tests.
  11. IMO Post pictures here before firing.
  12. If it helps we found color and thickness to be a primary cause. In our case we needed a tested glaze that worked pretty much no matter how the artist wanted to paint it else be accused of stifling creativity! Hence the glaze solution. I think I only increased the boron a few points, so .15 to .19ish. Marcias matte is on glazy if you want to double check what it was brought up to. Anyway, IF this is your issue folks have been successful at adding a tiny amount of boron fritt or GB to their underglaze colors prone to this. Tiny amount seems to be key else the glaze chem locally is a mystery. Hope that helps. As usual tesssssst.
  13. Same relay, so that is good, right form. The actual moveable contact on the new one has overheated without a sign of the terminal overheating which means either it was defective from the factory and misaligned or lots of load went through it. I would double check the wiring and element resistance as wired to be sure that 25 A or more continuous wasn’t going through it. If not, then it likely came misaligned and overheated during firing. IME it’s rare to see them melted without the melting occurring right at the connection first. The moveable contact on this one looks annealed. Definitely worth thorough check IMO before dropping a new one in.
  14. I suggest Double check your element resistance, the relay rating, relay wiring diagram as it could be a defective one but it really is hard and very unusual to melt one that way. Reminds me of double pole relays I saw earlier this year that were the wrong form. That relay ended up as form Z but looked identical to form C https://community.ceramicartsdaily.org/topic/25213-duncan-kiln-not-reaching-temperature/?do=findComment&comment=203748
  15. If a flame is coming out of the pilot assembly some way then that often indicates the orifice or pilot deflector / mixing tube is blocked or partially blocked. The thought here is the reference to vent is the pilot primary air location where air should go in, so if true then maybe some blockage in the pilot deflector / mixing tube and not the orifice. Remove and clean the assembly, often spiders like to nest in the deflector tube. Gently clean everything, do not enlarge the pilot orifice, maybe pass a tiny needle gently through the hole if blocked or blow it out backwards opposite to the typical flow. If you post a picture, this can be confirmed with a bit more confidence. A weak flame will not keep the gas valve engaged. The pilot flame should be reasonably strong and blue and engulf the thermocouple. Wispy and yellow generally will not work consistently.
  16. If my suggestion of using 1 tablespoon of underglaze seems to be wasteful then by all means scale it down. Yeah, thinking about this a little further, if they are using 2oz bottles then a tablespoon is probably a bit much for a test sample as that is a 1/4 of their stuff and UG is likely expensive for them. I see lots of folks with 2oz bottles for variety in color and pints for base colors they use. Actually just running this in my head with the tablespoon of underglaze assuming about 65% is raw materials with a likely percentage of 20% or more clay already in the formula, this probably kicks the clay up another 20% or more using the teaspoon of epk so maybe scale this all back considerably as well to start the test.
  17. If one is able to modify their glaze then testing as we did for color and thickness toleration is fairly easy especially with a boron based cone six glaze. In the end we had a tolerant glaze and the ease of testing led to being able to test whole panels of thickness, color, and manufacture easily, hundreds actually including combinations of thickness and color while minimizing the amount of underglaze used. If unable, there was the practice by some of adding a bit of Fritt to the underglaze and maybe not consuming a bunch of underglaze to get it to work. Gerstley and epk contain silica, alumina and flux, Gerstley not so much on the alumina, ……………… so maybe a good indicator, maybe not.
  18. Maybe. I can tell you what the testing revealed. Simple tests, where a light coat of underglaze is connected to a very thick coat of underglaze and the overglaze bubbles in the heavy area and stays smooth in the light area. Follow that with a better glaze melt (increased boron slightly) and all of a sudden the glaze begins to finish smoothly in the heavy areas. This proved true for matte and gloss overglazes btw. We share those results so folks can consider the result. I have learned though that there is often speculative disagreement and contention over this to which I try and phrase things as ………consider this possibility……. Simple to do your own test. The tests we did indicated something counterintuitive and helped us solve our problem.
  19. This would indicate that the coefficient of expansion of the fired clay and fired glaze are not close enough or compatible enough and delayed crazing will likely occur in items using this clay and glaze. It generally means adjust the glaze chemistry for a better fit or in the case of a commercial glaze use a different or more compatible one. Most mechanical or other solutions such as glaze thickness alleged will not really fix this and the combination will eventually craze. Most folks would consider this not suitable for food products and this would be a glaze defect when used with this claybody. Food and bacteria will accumulate in these cracks and the cup will be weaker than a non crazed equal. There are folks that consider crazing to be aesthetic and ok to use though. Most potters out of conservative caution will not sell crazed products for potential food use. Here is a good read IMO on glaze defects. The safety issues are summed up in paragraph seven. https://digitalfire.com/glossary/crazing
  20. Makes sense, it was not offered to complicate things it was offered as a diagnostic not presented in the other threads. If that is the issue, then there are other remedies than formulating your own glaze. We worked on this for over a year before concluding it was the central issue. Had someone pointed out the possibility it would have saved us a year of testing. Along with all the typical remedies everyone was speculating on at that time.
  21. What strikes me is this is going to be a very personal decision perhaps even influenced by the upcoming winter weather. There may be no perfect answer and trying both out might be a way to narrow this down or even deciding one is better during the winter than the other. As far as learning, always super nice to get instruction but also with all the content on the web a nice opportunity to learn on your own. So the pandemic is bad, but web learning opportunities have never been better and ……. People do become masters of their trade, craft, art by practice, application and study. Instruction is great but even with instruction practice is the only way to mastery. Maybe schedule the most travel convenient for the winter months and in the summer you can join the other. Both experiences likely will be beneficial and you get to choose when. As far as overwhelming knowledge, from my perspective, in clay there are many components to learn but learning step by step is really how humans progress. I enjoy learning and after over half a century it truly is what I enjoy most. A very wise person once told me when I was in my teens and was mad at myself for not accomplishing something fast enough muttering under my breath in disgust ……. He said “be careful how you treat yourself” that has stuck with me since and now when I look back I am pretty satisfied with all that I have learned and, excited about what I might get to learn tomorrow. For me I just need to add effort to my latest interest and pursue opportunities as I find them available. Not all work out perfect but over time they all seem to add nicely to a growing knowledge base. I wish you best of luck on your journey!
  22. There could be a lot of reasons for this but …….. the wheel circuitry has its own fuse so a short in the wheel likely would blow the onboard fuse and no longer trip any GFCI or breaker. The machine would no longer do anything no matter where plugged in. The other possibility is a damaged cord, cord grip, water has seeped into the unit and is tripping the ground fault. This is only a possibility but I would thoroughly examine the plug, cord,, cord grip and where it enters the wheel. If it’s tripping breakers then the short might be reasonably obvious. If it’s tripping ground faults then anything wet or even stains from having been wet can trip a GFCI.
  23. Something to consider: I do see bumps and we have seen this with many underglazes when applied thickly, usually uniform coverage thick. So the possibility to consider is the areas where underglazes are applied thickly can become refractory and the over glaze simply does not melt In these areas. After testing for over a year we found thickness as well as certain colors were more refractory. The end result was to formulate a clear gloss and matte that would melt better over these areas so the artists were free to create as they preferred with underglaze. It’s fairly easy to test for this condition and wash style painting rarely bubbles and is much more porous and less refractory than the heavy areas. So if all the wash areas are fine and many of the heavy application areas bubble, this is likely your issue. To make matters more confusing When underglaze is applied solid it also affects the amount of glaze that can be applied over it. Heavily underglazed areas will close off the pores in the bisque which will then take longer for the overglaze in that area to dry which means if double dipping, wait until the underglazed areas dry, they will take longer than the rest of the pot. Dip too soon and you likely remove as much overglaze as you put on. A thinner than normal layer of overglaze definitely makes the bubble condition more likely. Easy to test if this is your issue though.
  24. Here is a mix percentage for various rutiles you may have use for in the future - no significant chrome. https://glazy.org/materials/15393 It takes roughly 2.12 parts more Magnesium carbonate to equal 1 part Magnesium Oxide. Magnesium Dioxide is not a typical glaze chemical so I assume you intended to use Magnesium Oxide. So in your example above you would need approximately 3 g MgCO3 X 2.12 = 6.36 grams of Mag Carb (MgCO3) to equal 3 grams of Mag Oxide (MgO).. Magnesium carbonate does off gas or lose a great deal of its weight (Over half) when heated so it can cause other difficulties in some compositions. Here are some sample chrome tin recipes that may give you ideas when looking at their chrome and tin composition: https://glazy.org/recipes/77052 https://glazy.org/recipes/32817 https://glazy.org/recipes/79136 The last recipe has some nice line blend info to show the variations in color vs different alumina levels for that recipe. Chrome tin recipes can be a bit of a challenge. See below line blend. Cobalt glaze: Mauve / Pink / Lilac here https://glazy.org/recipes/5542 Careful with cobalt oxide and carbonate, same issue. You need just under. 1.5 times more Cobalt carbonate to equal 1 part oxide.
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.