JRW Posted April 5, 2021 Report Share Posted April 5, 2021 Hi All, I am having consistent trouble with blistering in my work. I have done a lot of research about how to troubleshoot this, and one of the solutions I have come across is doing a drop-and-soak firing. I am new to doing my own firings and to programming my kiln rather than using the pre-programmed schedules, but I tried the C6DHSC firing schedule. The result was pretty terrible. Glaze ran and pooled, blistered, and darkened. Clearly everything was over-fired, and it didn't even help with the blistering! In fact I now realized it may have made it worse. I’m using a Skutt electric kiln with the Kiln Master controller. Some of the glazes I'm using do better at cone 5, so I'm trying to find a full program/script that will both (1) help heal pinholes/blisters and (2) have a slow cool for better glaze outcomes (I've heard this is almost universally better than a natural cool). I know so much of this depends of the glaze and clay body. I am using Laguna S956 White Stoneware casting slip and various commercial glazes, mostly from the Amaco Potter's Choice series. If anyone is willing to direct me to the full programming schedule for something like this I would be very grateful! Link to comment Share on other sites More sharing options...
Hulk Posted April 6, 2021 Report Share Posted April 6, 2021 Hi JRW! Can't help you with your program, however, I'd like to suggest you identify your controller make and model - perhaps someone with the same setup can help. My kiln is manual - three switches for three zones, each with low, mid, high selection. I'm working with mid fire clays and glazes - started out looking to bend cone 6 cones full over, and have adjusted to cone 5 as well. I'm switching to low when peak temp is reached (no hold) until 100F drop, then twiddling the switches for a full hour to hold there, then I'm going back to low until drop to 1850F, when I'm shutting down and turning off the kiln vent as well. Once the temp has dropped well below 1000F, I'll turn the kiln vent back on if I'm looking to get a look sooner... Link to comment Share on other sites More sharing options...
Min Posted April 6, 2021 Report Share Posted April 6, 2021 Are you using cones to verify what the kiln reached? Post some pictures of the glaze issues with and without the drop/hold schedule. On 4/5/2021 at 10:05 AM, JRW said: Some of the glazes I'm using do better at cone 5, so I'm trying to find a full program/script that will both (1) help heal pinholes/blisters and (2) have a slow cool for better glaze outcomes (I've heard this is almost universally better than a natural cool) Does you kiln fire evenly? If the top or bottom runs cooler you could load the glazes that do better at ^5 in those areas. Not all glazes benefit from a slow cool, generally speaking clear gloss glazes or glazes without visual texture won't look any different with a fast or slow cool. Where slow cooling is really beneficial is with alkaline earth mattes (glazes that rely on high amounts of magnesium, calcium, strontium, barium (not recommended for functional ware) or zinc). If your commercial glazes don't look any different with or without a slow cool there is no point doing one. I do find a drop and soak/hold is beneficial for pinholes. Link to comment Share on other sites More sharing options...
Gumbercules Posted April 16, 2021 Report Share Posted April 16, 2021 On 4/5/2021 at 12:05 PM, JRW said: Hi All, I am having consistent trouble with blistering in my work. I have done a lot of research about how to troubleshoot this, and one of the solutions I have come across is doing a drop-and-soak firing. I am new to doing my own firings and to programming my kiln rather than using the pre-programmed schedules, but I tried the C6DHSC firing schedule. The result was pretty terrible. Glaze ran and pooled, blistered, and darkened. Clearly everything was over-fired, and it didn't even help with the blistering! In fact I now realized it may have made it worse. I’m using a Skutt electric kiln with the Kiln Master controller. Some of the glazes I'm using do better at cone 5, so I'm trying to find a full program/script that will both (1) help heal pinholes/blisters and (2) have a slow cool for better glaze outcomes (I've heard this is almost universally better than a natural cool). I know so much of this depends of the glaze and clay body. I am using Laguna S956 White Stoneware casting slip and various commercial glazes, mostly from the Amaco Potter's Choice series. If anyone is willing to direct me to the full programming schedule for something like this I would be very grateful! I’m definitely not the most experienced but it sounds like your kiln is over firing. How long is your hold on the top? I was having the same issue with blistering/cratering/runny glaze trying to heal with a top hold and the drop and soak schedule fixed this for me. I’m still experimenting but my schedule looks like this for cone 6 0-250f ramp 500f/hr 30min hold 250-350F 100f/hr 350-2100 350f/hr hold for 30min 2100-2230 108f/hr hold soak for 5-10min 2230-2100 9999f/hr hold again for 30min. 2100-1900 108f/hr hold again here to develop glaze colors. Usually 30min up to 90min. 1900-1200 108f/hr 1200-0 natural cooling I skip step 1 if they come right out of my drying oven into the kiln since they’ll have spent many hrs drying at 200F. Somethings I would suggest trying is to lower top temp by 30f and see if that helps. It’s possible the kiln is over reaching. If that doesn’t work then you could also try dropping your holding temp in 20f increments. Best of luck I know these problems can be really frustrating Link to comment Share on other sites More sharing options...
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