Dick White

The island/mound will occur when the proper amount of dry plaster has been added to the water in an appropriate size and shape bucket. However, an island/mound may also occur with the incorrect amount of plaster and /or an inappropriate size or shape bucket, and so the mere appearance of this infamous island/mound should not be regarded as the proper mixing ratio. The only accurate method to get a strong plaster mold is to add the exact weight of plaster to the exact quantity of water as specified by the plaster manufacturer. The ratio of plaster to water is different for plaster of paris vs. pottery #1 plaster.

The island/mound will occur when the proper amount of dry plaster has been added to the water in an appropriate size and shape bucket. However, an island/mound may also occur with the incorrect amount of plaster and /or an inappropriate size or shape bucket, and so the mere appearance of this infamous island/mound should not be regarded as the proper mixing ratio. The only accurate method to get a strong plaster mold is to add the exact weight of plaster to the exact quantity of water as specified by the plaster manufacturer. The ratio of plaster to water is different for plaster of paris vs. pottery #1 plaster.

The island/mound will occur when the proper amount of dry plaster has been added to the water in an appropriate size and shape bucket. However, an island/mound may also occur with the incorrect amount of plaster and /or an inappropriate size or shape bucket, and so the mere appearance of this infamous island/mound should not be regarded as the proper mixing ratio. The only accurate method to get a strong plaster mold is to add the exact weight of plaster to the exact quantity of water as specified by the plaster manufacturer. The ratio of plaster to water is different for plaster of paris vs. pottery #1 plaster.

The island/mound will occur when the proper amount of dry plaster has been added to the water in an appropriate size and shape bucket. However, an island/mound may also occur with the incorrect amount of plaster and /or an inappropriate size or shape bucket, and so the mere appearance of this infamous island/mound should not be regarded as the proper mixing ratio. The only accurate method to get a strong plaster mold is to add the exact weight of plaster to the exact quantity of water as specified by the plaster manufacturer. The ratio of plaster to water is different for plaster of paris vs. pottery #1 plaster.

Many studios use plastic dry cleaner bags to wrap the fresh greenware. I have not been in a dry cleaner establishment in the 15 years since I retired from my real day job downtown, so I ask students to bring in theirs. One studio I work with went to whatever supply house and got a full 1000 piece roll just like the cleaners use; we've been working that roll for 4 years and still have half. The dry cleaner bags seem to have a reasonably predictable permeability for drying by next class time, and they are thin, light, and flexible so the ware is not smushed when wrapping it. The problem is that few students take the time to cut the full bag into appropriate size pieces, so the work-in-progress ware shelves are loaded with single mugs on 12" square boards wrapped in an entire bag (and because it is still a bag, it's a double layer draped over the mug). And then some Helpful Hanna/Harry brings in an armful of garment bags scavenged from the department store when the stock clerk was unwrapping and setting out the spring fashions - a completely different type and weight of plastic. And don't get me started on the empty clay bags that show up in the bin. After all, plastic is plastic, isn't it? Well, no, as you point out there is plastic and there is *plastic*, not all the same.
All that said, when the bin is running low (with 125 students cranking out production), I have picked up a package of cheap lightweight painter's drop cloth from the local blue or orange big box, like your suggestion (except I get the lightweight 3-pack, yours is midweight). I've also noticed that the community center uses the cheapest lightest thinnest trash bags, so I have raided the janitor closet.
Carry on, we are comrades in arms...

... another link from the Paragon website. Paragon bought the Duncan line when they went out of business. https://eadn-wc04-7751283.nxedge.io/wp-content/uploads/LX851_Duncan_Energy_Saver_Owner_Manual.pdf
dw

... another link from the Paragon website. Paragon bought the Duncan line when they went out of business. https://eadn-wc04-7751283.nxedge.io/wp-content/uploads/LX851_Duncan_Energy_Saver_Owner_Manual.pdf
dw

If you're sure it's 2.5" brick, then are you sure it's a KM1227? Skutt doesn't make the 1227 with 2.5" brick. Is it a 1027?

There are several issues in play here. First, about cone numbers - if you download a cone chart from this link https://www.ortonceramic.com/files/2676/File/Orton-Cone-Chart-F-022-14.pdf you will see the temperature/rates for every cone. Note that there is no cone 0, and cone numbers from 01 and up are actually running backwards, the temperatures getting colder as the number gets higher; cone numbers without a O in front of the number run as you would expect, the temperatures increase as the number gets higher. Thus, your array of cones 04, 5, and 6 do not relate to each other. There is 200+℉ difference between 04 and 5, which is why the 5 and 6 cones are unmoved when fired to 04. Cones above 3 are different colors in the box so you can easily tell them apart when loading the kiln, but the dye burns out during the firing, leaving them white. 
Second, about the accuracy of programmable kilns - they are not accurate out of the box. More often than not, they tend to fire hotter than the nominal temperature shown on the screen. The reported maximum temperature will correlate correctly to the Orton cone table linked above, meaning that the final temperature attained at slow speed will be lower than the temperature reported for medium speed, and higher yet for fast speed. That's just the way cones work - the bending process takes time as well as temperature to penetrate to the center of the cone (and the center of a ceramic piece). But back to the kiln accuracy - if the kiln is firing hotter or cooler than the cone bend, you can calibrate the controller to, in effect, fool it to add or subtract a certain number of degrees to what the thermocouple seems to be reporting, and thus adjust the actual results so that cone 5 (let's say) on the screen properly bends cone 5 inside the kiln. If you have never played with the controller adjustments, you should call Skutt and ask one of the technical reps to walk you through the process.

There are several issues in play here. First, about cone numbers - if you download a cone chart from this link https://www.ortonceramic.com/files/2676/File/Orton-Cone-Chart-F-022-14.pdf you will see the temperature/rates for every cone. Note that there is no cone 0, and cone numbers from 01 and up are actually running backwards, the temperatures getting colder as the number gets higher; cone numbers without a O in front of the number run as you would expect, the temperatures increase as the number gets higher. Thus, your array of cones 04, 5, and 6 do not relate to each other. There is 200+℉ difference between 04 and 5, which is why the 5 and 6 cones are unmoved when fired to 04. Cones above 3 are different colors in the box so you can easily tell them apart when loading the kiln, but the dye burns out during the firing, leaving them white. 
Second, about the accuracy of programmable kilns - they are not accurate out of the box. More often than not, they tend to fire hotter than the nominal temperature shown on the screen. The reported maximum temperature will correlate correctly to the Orton cone table linked above, meaning that the final temperature attained at slow speed will be lower than the temperature reported for medium speed, and higher yet for fast speed. That's just the way cones work - the bending process takes time as well as temperature to penetrate to the center of the cone (and the center of a ceramic piece). But back to the kiln accuracy - if the kiln is firing hotter or cooler than the cone bend, you can calibrate the controller to, in effect, fool it to add or subtract a certain number of degrees to what the thermocouple seems to be reporting, and thus adjust the actual results so that cone 5 (let's say) on the screen properly bends cone 5 inside the kiln. If you have never played with the controller adjustments, you should call Skutt and ask one of the technical reps to walk you through the process.

There are several issues in play here. First, about cone numbers - if you download a cone chart from this link https://www.ortonceramic.com/files/2676/File/Orton-Cone-Chart-F-022-14.pdf you will see the temperature/rates for every cone. Note that there is no cone 0, and cone numbers from 01 and up are actually running backwards, the temperatures getting colder as the number gets higher; cone numbers without a O in front of the number run as you would expect, the temperatures increase as the number gets higher. Thus, your array of cones 04, 5, and 6 do not relate to each other. There is 200+℉ difference between 04 and 5, which is why the 5 and 6 cones are unmoved when fired to 04. Cones above 3 are different colors in the box so you can easily tell them apart when loading the kiln, but the dye burns out during the firing, leaving them white. 
Second, about the accuracy of programmable kilns - they are not accurate out of the box. More often than not, they tend to fire hotter than the nominal temperature shown on the screen. The reported maximum temperature will correlate correctly to the Orton cone table linked above, meaning that the final temperature attained at slow speed will be lower than the temperature reported for medium speed, and higher yet for fast speed. That's just the way cones work - the bending process takes time as well as temperature to penetrate to the center of the cone (and the center of a ceramic piece). But back to the kiln accuracy - if the kiln is firing hotter or cooler than the cone bend, you can calibrate the controller to, in effect, fool it to add or subtract a certain number of degrees to what the thermocouple seems to be reporting, and thus adjust the actual results so that cone 5 (let's say) on the screen properly bends cone 5 inside the kiln. If you have never played with the controller adjustments, you should call Skutt and ask one of the technical reps to walk you through the process.

Put a single layer of Saran Wrap or similar thin plastic film over the silver bowl to protect it from possible chemical reactions with something in the clay. It is probable that nothing untoward would happen with the clay in the bowl, but don't take the chance on the unknown.

Put a single layer of Saran Wrap or similar thin plastic film over the silver bowl to protect it from possible chemical reactions with something in the clay. It is probable that nothing untoward would happen with the clay in the bowl, but don't take the chance on the unknown.

Well, actually, the elements in those wiring diagrams are in series. There are 4 separate elements total, 2 in each of the sections. To measure the resistance of each section, apply the multimeter probes at the power inputs to the elements. The resistance will be the sum of the two individual elements. For example, in the B18 diagram, each section has two elements of 10.2 ohms each, which should measure as 20.4 ohms across the power leads. Thus using an Ohms Law calculator, that section running at 240V will draw 11.7 amps. Doubling that for both the top and bottom sections yields 23 amps total, which is slightly more than the stated 22 amps, but close enough to allow for some slippage and wear. Continuing the example for the 23H model, each section has a 7.8 ohm and 6.6 ohm element in series, for a measured total of 14.4 ohms across the power leads to the elements of that section.  At the specified 208V, each section is drawing 14.4 amps, which doubled for both sections of the kiln yields total amperage of 28.8 amps, which rounds to the specified 29 amps.
You correctly note that some kilns  have elements with different resistances. The B23 drawing you found is an example of that. In the top section, the element closest to the top is 7.8 ohms and the one in the middle is 6.6 ohms. The bottom section is the reverse, with the 7.8 ohm element closest to the base and the 6.6 ohm one in the middle. You say the Cress rep told you the top and bottom elements are 9.2 ohms. If we assume that your B23 is also rated as 29 amps total but at 240V (confirm that on the electrical rating plate on your kiln, I am just guessing here), then the amperage per each top and bottom section will be ~14.5 amps, which calculates to a resistance of ~16.5 ohms total for the two elements in series in the section. If one is supposed to be 9.2 ohms, the other must be 7.3 ohms.
.

Put a single layer of Saran Wrap or similar thin plastic film over the silver bowl to protect it from possible chemical reactions with something in the clay. It is probable that nothing untoward would happen with the clay in the bowl, but don't take the chance on the unknown.

Some feldspar history... G200 was a potash feldspar mined in Monticello, Georgia, but the ore was higher in potassium than other comparable potash feldspars, such as Custer. To resolve this difference, they blended it 70:30 with a soda feldspar brought in from a mine in Spruce Pine, North Carolina. About 15 years ago, the bean counters decided that trucking soda feldspar 300 miles to just to mix it with another feldspar was not economical, so they stopped that. The plain potash feldspar from the Monticello mine was relabeled as G200HP (for High Potassium) and the ceramic industry was advised to mix their own if we wanted to replicate the old G200. Some of us did, some of us bought a product blended by Lauguna and marketed as Old Blend, and others of us moved on to other brands of potash feldspar. About 10 years ago, the Monticello mine was exhausted, and G200HP is no more. The Imerys Corporation (which now owned the mine and product) found a potash feldspar similar to the old blended  product (and other potash feldspars) in Spain and began importing it as G200EU.
So, to answer your specific question - no, you can't buy G200HP anymore (but I know someone who has some). There is nothing else like it on the market that has that high level of potassium. I don't know if you can trust the label of what you just got as actually the old blended G200 that has not been widely available for a long time or maybe is the Spanish G200EU. Because of these nuances, using another brand of feldspar with your remaining G200HP or in place of it is likely to change the way your G200HP recipes turn out. Or you can take a deep dive into some glaze chem software and sort it out from there.

Some feldspar history... G200 was a potash feldspar mined in Monticello, Georgia, but the ore was higher in potassium than other comparable potash feldspars, such as Custer. To resolve this difference, they blended it 70:30 with a soda feldspar brought in from a mine in Spruce Pine, North Carolina. About 15 years ago, the bean counters decided that trucking soda feldspar 300 miles to just to mix it with another feldspar was not economical, so they stopped that. The plain potash feldspar from the Monticello mine was relabeled as G200HP (for High Potassium) and the ceramic industry was advised to mix their own if we wanted to replicate the old G200. Some of us did, some of us bought a product blended by Lauguna and marketed as Old Blend, and others of us moved on to other brands of potash feldspar. About 10 years ago, the Monticello mine was exhausted, and G200HP is no more. The Imerys Corporation (which now owned the mine and product) found a potash feldspar similar to the old blended  product (and other potash feldspars) in Spain and began importing it as G200EU.
So, to answer your specific question - no, you can't buy G200HP anymore (but I know someone who has some). There is nothing else like it on the market that has that high level of potassium. I don't know if you can trust the label of what you just got as actually the old blended G200 that has not been widely available for a long time or maybe is the Spanish G200EU. Because of these nuances, using another brand of feldspar with your remaining G200HP or in place of it is likely to change the way your G200HP recipes turn out. Or you can take a deep dive into some glaze chem software and sort it out from there.

Yes, no, maybe. We have no clue what colorants or what amounts of said colorants are in commercial underglazes. As for Mason stains (i.e., Mason brand), they do publish a reference document showing what colorants are in each stain number, but not amounts. Of the 5 black stains, 6600 and 6612 are listed as compatible with either zinc-free or zinc-contain glaze. The others, 6650, 6657, and 6666, specifically state zinc-free glaze needed. The issue is that zinc and chrome do not play well together. About 75% of the Mason stains have some chrome in the mix of colorants, so a zinc-containing glaze will alter the intended color of the stain. Hence, zinc-free being the go-to recommendation, especially for underglazes for which there is no public data.

Yes, no, maybe. We have no clue what colorants or what amounts of said colorants are in commercial underglazes. As for Mason stains (i.e., Mason brand), they do publish a reference document showing what colorants are in each stain number, but not amounts. Of the 5 black stains, 6600 and 6612 are listed as compatible with either zinc-free or zinc-contain glaze. The others, 6650, 6657, and 6666, specifically state zinc-free glaze needed. The issue is that zinc and chrome do not play well together. About 75% of the Mason stains have some chrome in the mix of colorants, so a zinc-containing glaze will alter the intended color of the stain. Hence, zinc-free being the go-to recommendation, especially for underglazes for which there is no public data.

Nice job, been there done that too. Some years ago I acquired a little Paragon 1193 of about the same size, and also 120V, 19 amps. I thought it would be a nice test kiln. Not so, the elements kept wearing too fast at cone 6, despite it nominally being a cone 10-capable kiln. It had a 3-button Sentry controller. So, I did the math, changed the plug to a 20 amp 240 plug, swapped in a double breaker, but didn't need to change the wiring through the wall as it was already 12 ga. Bought a pair a generic 12 amp elements from Kreuger, wired them in series, and swapped out the Sentry controller for a Genesis Mini. Also sprang for an S thermocouple. 30% more power and 100% more accuracy. No space for the SSR stuff, so keeping the standard relay.

Nice job, been there done that too. Some years ago I acquired a little Paragon 1193 of about the same size, and also 120V, 19 amps. I thought it would be a nice test kiln. Not so, the elements kept wearing too fast at cone 6, despite it nominally being a cone 10-capable kiln. It had a 3-button Sentry controller. So, I did the math, changed the plug to a 20 amp 240 plug, swapped in a double breaker, but didn't need to change the wiring through the wall as it was already 12 ga. Bought a pair a generic 12 amp elements from Kreuger, wired them in series, and swapped out the Sentry controller for a Genesis Mini. Also sprang for an S thermocouple. 30% more power and 100% more accuracy. No space for the SSR stuff, so keeping the standard relay.

True. If the kiln pulls 48 amps and you take away one section, or 1/3 of the elements (we'll assume all the elements are the same), then you'd have a kiln that pulls 32 amps. However the 32 amps isn't enough power. The issues is that there's a lot of heat loss out the lid and the floor, and the 4 elements don't have the power to deal with that like the 6 elements did. So we have to increase the power of the 4 elements to make up for it. So you end up with a 40 amp kiln with 2 sections, and a 48 amp kiln with 3 sections. The only way to really save power is to go to a smaller kiln.

We'd rather keep you in the group to talk about your pottery than see you living in a motel fighting with the insurance company after a fire.

We'd rather keep you in the group to talk about your pottery than see you living in a motel fighting with the insurance company after a fire.

Several concerns about the current state of affairs - you took out the bottom section, which changes the amperage draw from 48 amps to 31 amps, assuming the elements are the correct ones for a 240V 1027 kiln. That requires a 40 amp circuit, including the associated wiring. You said you were using a dryer circuit, which is typically a 30 amp circuit. You say the electrician changed the circuit breaker. Changed it to what amperage? If the sparky put the required 40 amp breaker on an existing 30 amp circuit, you need a new sparky and hope your homeowner's insurance is paid up.
Regarding the kiln itself, the design of Skutt kilns places hotter elements in the top and bottom rows to compensate for heat losses through the lid and base. The middle 4 rows of elements are cooler because less heat is need in the middle compared to the top and bottom. By removing the bottom section, you have eliminated that one element at the bottom that needs to be hotter. It may have somwhat unbalanced heating now. Furthermore, though it is now the size of a 1018 kiln, kilns are designed with optimal ratios of heat to kiln surface area. The standard 1018 kiln needs 39 amps to perform up to maximum expectations. Yours now has only 31 amps. Thus, you will probably be limited to cone 6 at best.