Min

When I want a lot of little bowl shapes I do the same thing as Tom then press them on my bent elbow for super quick rough and ready bowl shaped test tiles. cling film / saran wrap on the clay so it doesn't stick to the can.

I agree with Neil, narrow down the claybody choice first. You could use one of the lighter clays like B-mix for the test tile then paint a stripe of slip made from the darker claybody onto it. (get the slip on as soon as possible) It isn't ideal but will give you an idea of what the same glaze looks like on a light and dark body using one test tile. I find it's a real pain keeping light and dark claybodies separate insofar as cross contamination of wheel, tools, batts etc.

Refiring a blistered piece will give some info about whether the glaze has high fluidity plus high surface tension in addition to what firing higher than the recommended cone is doing to the glaze. If the blisters get worse it supports the theory of the glaze being highly fluid with a high surface tension. Agree re-fires are a crap shoot but the reason to try it in this circumstance is to determine the glaze quality, not necessarily to fix a blistered pot but that would be a nice bonus if it happened. Since the refired pot didn't get worse it's probably safe to go a bit hotter than the last fi

@Salt.Forest, any chance you have another white cone 6 clay that you can try these glazes on at the same time?

Sounds like soluble salts. Can you post a picture?

Agree that the glaze looks too thick in the middle of the bowl. Looks like the drop and hold helped somewhat but not enough. Since we don’t know the makeup of the glaze it’s hard to say if it’s an early melter. Early melters can need to go lower for the second soak as they are fluid at a lower temperature than glazes that are late melters. if I was testing this clay and glaze i’ld change your second rate to 400/hr to 2000. Second to last ramp is too slow, needs to drop quickly @9999 down to second hold temperature. What the temperature for the second hold needs to be will be trial

1 - see chart below 2 - Yes, they can be re bisque fired. Common to bisque mid and high fire clay to cone 04. KilnFiringChart.pdf Welcome to the forum.

Try 15 minutes for the second soak. It's difficult to dial it in specifically with the first try but this should give you some info. ie if the blisters are worse/better/same. I'ld also include one of the blistered pots in the next firing, see if the blisters get worse. (put the pot on a waster slab in case of glaze runs) "this seems like a glaze schedule problem, not a bisque schedule problem, right?" Glaze blisters can be one of the trickier faults to figure out. It could very well be a combination things, glaze itself and some part of the glaze firing schedule. Have you had successful

I use 327100.

Error 4 "Firing temperature has exceeded soak temperature program by 20C" From this manual, looks like it's the one you have. http://www.rlkilnservices.co.uk/controller_manuals/Studio 1800 Manual.pdf Welcome to the forum

Are the other glazes rutile glazes too? Glazes high in rutile can be problematic for pinholes and blisters. I'ld suggest trying a soak just under your top temperature then dropping 100F and doing a second soak for 20 minutes. There isn't a one size fits all top temperature and soak to get to cone 6. What temperature did your programmed ^6 take you to? What works for my kilns is going at 108 from 2000 to peak temperature of 2185 then doing a 15 minute soak then dropping to 2085F and doing a second soak. The second soak allows the pinholes and blisters time to heal over without overfiring

Classic bloats from overfiring the clay, your cone 6 body doesn't like being fired to cone 8.

To some degree you can vary the coarseness of the abrasive by changing the speed. Speeding it up will make it act like a finer grit, slowing it down makes it more like a coarser grit. For safety the maximum rpm of any grinding wheel is set by the manufacturer, they can explode going overspeed.

Thanks for the update, good to know the results but too bad there were a few pinholes.

No you don’t need to hold the trip arm up by hand. After the kiln trips off lift the trip arm up to about 45degrees then press the white button and gently release the trip arm. It will rest without tripping the power switch off. Kiln will keep firing until you either press the trip arm down to (re)depress the trip arm to trip the power switch or if your kiln has a timer it runs down and shuts off the power. It will take a fair bit of experimenting to figure out how long to hold it without a pyrometer, you’ll need to figure out a schedule for turning the elements down so you don’t overfire t