Skutt electric kilns are designed with the goal of having uniform heat throughout the entire kiln chamber. This is primarily accomplished through the use of balanced elements installed at the top and bottom of the kilns to help compensate for the natural heat loss that occurs through the lid and floor of a kiln. The center of the electric kiln is typically the hottest area simply because of a higher concentration of elements. By putting elements that get slightly hotter at the top and bottom of the kiln and elements that don’t fire as hot in the center of the kiln, the heat is more evenly distributed throughout the entire chamber.

Balanced elements do a good job of evening out the heat throughout a kiln, especially taller models like the 1027 and 1227, but other factors can influence distribution of heat and cone bends throughout the chamber including:

• Separation of kiln shelf layers
• Thermocouple placement
• Evenness of kiln load
• Density of load
• Shelf size
• Firing speed/heating rates
• Hold time
• Use of an EnviroVent 2 downdraft system
• Cone type
• Cone placement

Separation of Kiln Shelf Layers and Thermocouple Placement

There are many reasons that a kiln can fire unevenly. Barring a mechanical problem like an element or relay not functioning, the most common issue we encounter is poorly loaded kilns with shelves stacked too tightly together.

Separation of kiln shelf layers can have a dramatic effect on fired results. The tighter the shelf layers, the more challenging it is for radiant heat from the elements to penetrate evenly between the layers. This is especially true at the top and bottom of the kiln where a more significant amount of heat is lost through the lid and floor slabs. Balanced elements help, but they can only do so much to compensate.

Recommended loading patterns include placing a one-inch post on the kiln floor, then the first kiln shelf, followed by a 5-6-inch-tall kiln post and then the second shelf layer, etc. Using a taller kiln post between the first and second layer in the bottom of the kiln effectively exposes that layer to two full rows of element coils in the side walls. This typically gives the best ability for more uniform heat in that area.

The same theory holds true at the top of the kiln.  The uppermost shelf should be placed no closer than approximately 5 inches from the underside of the lid, such that two full rows of element coils are visible to radiate heat onto that shelf layer.  Shelves stacked tighter at the top and bottom of the kiln have a greater likelihood of being underfired.  While each kiln is different and some clay and glazes are more forgiving than others, if consistency and uniformity of heat is required, then the shelves at the top and bottom of the kiln need to be exposed to more radiant heat.

The shelves in the center of the kiln can generally be stacked somewhat tighter because it is naturally hotter in that area.  Two-inch posts can potentially be used for flat objects, but often three inch or taller posts are better for low objects.  The exception to this is the shelf layer near the thermocouple in the middle of the kiln.  Skutt recommends an ideal clearance of two inches all around the tip of the thermocouple so that it can measure temperature unobstructed.  Kiln shelves, posts, or pottery placed very close to the tip of the thermocouple can interfere with its ability to measure air temperatures accurately. 

Density and Evenness of Kiln Load

Evenness of kiln load and density of load can also impact fired results.  Tall kilns that are loaded very unevenly will not fire uniformly.  Four shelf layers in a 27-inch-tall kiln is average.  If six-inch posts were used between each of the four layers, the load would be very evenly distributed and the kiln should fire quite evenly.  However, as an extreme example, if all four layers were stacked with plates at the bottom of the kiln using two-inch posts between the layers and the uppermost shelf was wide open to the lid, the kiln would not fire accurately and the plates on the lower shelves would be underfired because the heat could not radiate in between the very tight layers. 

Kilns can be successfully fired partially full if needed.  For instance, if there is enough work to fill approximately 40% or more of the kiln, the items should be spread out to make use of the entire kiln chamber, rather than being concentrated at the bottom of the kiln.  If there is less than 40%, or approximately 1/3 of a full kiln load, then the shelves should be propped up and the pieces placed on one or two shelf layers in the center of the kiln.  Taller kiln posts (approximately six inches) should be used to separate the shelves in this case to let the kiln to be as open as possible between those layers and to allow ample room around the thermocouple.    

Kiln Shelf Size

Selection of kiln shelf size in relation to chamber size is also important.  Shelves that are too wide for the chamber can restrict heat flow throughout the kiln.  Ideally, there should be approximately one-inch or more of clearance between the edge of the kiln shelf and the wall of the kiln chamber.  Shelves that extend too close to the kiln wall can effectively cut off the ability of heat to move more easily throughout the kiln chamber. 

Firing Speed

The choice of firing speed should be made according to the scale of work and cone temperature being fired to.  The kiln should be fired according to the needs of the weakest link inside, which is the biggest, thickest, or wettest item in the firing. 

Preset modes include Slow, Medium, and Fast.  Fast is primarily designed for China paints, lusters, overglazes, and decals – firings that go to relatively low temperatures and can be done quickly.  Fast mode can occasionally be used successfully for some higher temperature glaze firings, but it is often not recommended because it is typically too fast for most clay and glazes to mature properly.  It is not recommended for most bisque firings.  More often the choice should be limited to Slow or Medium.  The selection is decided based on how physically thick or large is the work in the kiln.  As a general rule, the larger or thicker the item, the slower it should be fired. 

Work that is similar in thickness to that of a pencil (3/8” or less) is generally considered “average” thickness and can be safely fired on Medium speed.  The exception to this would be for very large objects.  Items approximately 15-18 inches or more in any dimension or pieces that nearly fill the full width or height of the kiln should be fired on Slow so that the entirety of the piece can heat up more uniformly. 

Items that are approximately 1/2-inch thick should be fired on Slow.  These would be considered “thick” and need to be fired more slowly so that the exterior of the clay does not get substantially hotter than the interior.  A significant temperature differential on the same piece, because of thickness or extreme size, can lead to stress in the clay which promotes cracking.  Items that are more than approximately ¾-1-inch thick or greater may need to be fired using a custom program that slows the entire program down even more to accommodate for the extra thickness. 

Heating and Cooling Rates

The programmed heating rate in the final segment of the firing is what primarily impacts the heat work attained in the kiln.  Heat work is the measurement of time and temperature together.  The faster something is fired, the hotter the peak temperature needs to be.  The slower it goes, the lower the temp can be.  Fast mode is programmed to heat at a rate of 200 °F per hour in the final 250 °F of the program.  For comparison, the Medium speed mode is programmed at 120 °F per hour and Slow is at 80 °F per hour.  Orton calibrates their cones to a rate of 108 °F per hour in the final segment. 

Because heat work is achieved during the final segment, cooling rates, unless programmed to be exceptionally slow, do not typically impact cone bend results in electric kilns the way they might in a gas kiln with substantially thicker walls and more mass that continues to radiate heat after the firing has completed.  Electric kilns typically drop rapidly in temperature very quickly after the power is shut off to the elements.  The rate is quick enough that 200 °F can easily be lost in the first 20 minutes following completion of a firing.  Once the kiln has cooled that much, heat work is no longer a factor for the clay and glaze maturity. 

Hold Time

A short hold time of 5-15 minutes at the peak temperature is a simple method of helping to even out heat work throughout a kiln chamber.  For example, if one section of the kiln is a half cone cooler than the rest of the kiln, a 10-minute hold at the peak temperature may be all that is needed to even out the heat work in the kiln.  Because the middle of the kiln tends to be the hottest area, the hold time will tend to fire the middle of the kiln slightly hotter.  For clay and glazes that appear to be underfired when the target cone is partially bent, this is a good indication that they can handle the extra heat.  In this instance, firing to get the coolest part of the kiln up to a minimum cone temperature is appropriate strategy even if it risks getting the middle of the kiln slightly hotter. 

Downdraft Venting

A properly installed EnviroVent 2 downdraft vent system can also have a slight impact on heat uniformity in the kiln chamber when it is operating by drawing a small amount of heat toward the bottom of the kiln. 

Cone Type and Placement

Skutt recommends using Orton self-supporting witness cones for the most accurate measurement of ceramic heat work.  If large witness cones are used, they should be placed into Orton cone plaques rather than lumps of clay for more consistency.  Junior kiln sitter cones are not designed to be used as witness cones. 

Cones should be placed approximately 2 inches from the edge of the kiln shelf so that they are in a similar location to the heat being measured by the tip of the thermocouple.  Cones placed in the middle of the kiln shelf will naturally be slightly cooler, especially in larger diameter kilns, because they are physically further away from the radiant heat of the elements and they may be shielded by pottery in the kiln.  The variation will not be dramatic but it would be enough to show a difference in the cone bend.  If a user is comfortable monitoring cones during a firing while wearing kiln glasses, the cones can be placed directly in front of the peep holes for viewing during the firing.  If only one cone is used, it should be placed on the kiln shelf closest to the thermocouple.  As a general practice for consistency, cones should routinely be placed in the same location in the kiln during each firing for better comparison over time. 

Check out more helpful kiln articles on our blog. 

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Choosing a kiln for your classroom is both exciting and a little scary. This is certainly one of the largest capital expenditures an Art Teacher will make in their career, and you want to get it right.  

We created a great document that addresses everything you need to know about choosing the right kiln. We suggest you download this Kiln Management pdf here for more detail. It even has an order sheet with signoff spaces for the Architect, Contractor, and Art Teacher to make sure everyone is on the same page. In this article we will go over the high points. 

Type of Kiln 

There are many styles of kilns to choose from however, most schools choose a top loading electric kiln like the one pictured here for the following reasons:

• They are the best value in terms of cost per cubic/foot. 
• Electric kilns are easier to use and safer than gas kilns. 
• Contrary to popular belief, they are actually easier to load than frontloading kilns because you do not have to cantilever the weight of heavy shelves away from your body which could place undo stress on your back. 
• They have a sectional design that allows them to be easily taken apart to move through doorways and staircases. Frontloading kilns are not only much heavier, many are too large to move through standard doorways and can pose problems when trying to move them into the designated kiln room. 
• The controllers on these kilns are designed to be intuitive and are easy to learn, even for teachers who are new to ceramics. The KMT controller pictured here has a kiosk style programming mode that walks the teacher step by step through the process. 

Size of Kiln 

The size and number of kilns needed for your school will be a direct function of how many students are in the program and the size of the projects they will be making. The most common sizes used in schools are the 10 cu/ft and 7 cu/ft models.  

The image below from the Skutt website shows how many 6” bowls can fit in a 7 cu/ft KMT1027 kiln. For this model it is 39. A 10 cu/ft KMT1227 kiln can hold 50 6” tea bowls.  Using this image as a tool, you may determine that you will need 2 KMT1227-3 kilns to handle the ware your program of 100 students produces. If that is not in the budget you can just purchase one kiln but will need to do multiple firings. 

A 6” tea bowl is a good representation of an average size of a student project. If your students are going to produce larger projects, you will need to take that into account when sizing you kiln. 

Sometimes the options for where you can locate the kiln in a school are limited. You will want to be sure the space you choose will allow for the footprint of the kiln plus, the 20” of clearance required by code. The outside measurements of all Skutt Kilns can be found at Build A Spec. 

Electrical Specifications 

Ordering a kiln that does not match the electrical supply available at the school is one of the most common mistakes purchasing agents make and it is an expensive mistake. If the kiln does not match the supply it needs to be shipped back to the factory at the schools expense. Also, if it is not packed correctly in the original packaging, there is a strong likelihood that the kiln will be damaged in transport and the school would be liable for the entire cost of the kiln. 

In most schools the available supplies are: 

• 240 Volt/1 Phase 
• 208 Volt/1 Phase 
• 240Volt/3 Phase 
• 208 Volt/3 Phase 

Unlike many other electrical appliances, kilns need to be matched to the exact supply they will be hooked up to. Do not let anyone tell you 220 Volt. This is a generic term in the USA for either 208 Volt or 240 Volt. Use the form mentioned earlier in the Kiln Management document to have them sign off and verify the voltage before ordering the kiln.  

Venting 

There are basically 3 main purposes for venting: 

• To remove heat from the room 
• To remove fumes created by the firing process from the room 
• To create an atmosphere inside the kiln that is beneficial to the ware 

If the kiln room exceeds 100 °F the kiln is designed to shut off to protect the electronics in the controller. Most kiln rooms are equipped with an overhead vent sized by an HVAC professional to ensure the room stays below temperatures that could shut down the firing. 

A downdraft vent like Skutt’s EnviroVent 2 is installed to take care of the fume removal and improving the chamber atmosphere. The vent is powered by a fan motor mounted to a wall which is connected to a collection cup which fits up under the kiln floor and draws air through small holes drilled in the slab. The fumes are then evacuated from the room much like a clothes dryer.  

This process brings fresh oxygen into the kiln chamber which improves combustion and helps to even out temperatures throughout the kiln.   

Accessories 

You will need a few additional kiln accessories to fire your kiln. To load ware in layers in the kiln you will need a furniture kit. This is composed of various sized refractory posts that are used to stack the shelves along with the shelves themselves. Each kiln model has it’s own recommended furniture kit with the number and size of shelves and posts matched to fit the model. 

You will also want to purchase some pyrometric cones which are used in each firing to measure the accuracy of the thermocouple and the uniformity of heat within the kiln chamber. 

Want to stay up-to-date with teacher and education-related product news and events? Sign up for our newsletter here, and make sure to check the “school teachers” email list. 

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Choosing a pottery wheel that best fits your needs appears at first glance to be a fairly simple proposition. When you actually dig into all of the details associated with your choice it can be a little daunting. Hopefully this article will bring a little focus to the decision-making process. 

Skutt Prodigy pottery wheel

One of the primary factors that guides every purchasing decision is price. A pottery wheel can last a lifetime if you take care of it. However, you may find that your commitment to the craft may not be as permanent. Potter’s wheels can range in price from a few hundred dollars to a few thousand. We suggest that you begin with an entry level wheel. As your throwing style evolves, you will have a better understanding of the features and specifications worth more investment.  

Entry Level Wheels 

Don’t spend too much…but don’t spend too little 

A quick Google or Amazon search will bring up wheels that cost under $500. These are basically toys for children, not serious tools to develop your craft. Many of them are cheap imports that either lack the power necessary to properly throw a pot or are of such poor quality, the will only bring frustration as they disintegrate before your eyes. 

As a general rule, stick to name brands. You should plan on spending between $800 and $2000. Also, you will want to avoid table-top models. Most people quickly advance beyond their capabilities. Your clay supplier can be an excellent resource to recommend a beginner wheel that is right for you. 

Your Forever Wheel 

Okay, so now you are hooked. You have determined that throwing pots is a passion that will last a lifetime and your skills have advanced to a level that you can appreciate the features that justify spending a little more money on a wheel. You will want to explore the following characteristics when choosing your Forever Wheel. 

• Power 
• Fit and Weight 
• Wheel noise 
• Unique Features 
• Customer Service and Warranty 

Power – It’s All About Torque 

“Torque is a measure of the force that can cause an object to rotate about an axis.” 

When wheel manufacturers describe the power of their wheels, they generally talk in terms of horsepower (HP) or how much clay the wheel is capable of centering. These descriptions of power can be misleading and subjective. The true measure of a wheel’s power is torque.  

The amount of clay that can be centered on a wheel has a lot to do with the skill level of the potter. The amounts that manufacturers list in their marketing materials seem to be more dependent on what their competition is listing then any scientific measure.

Motors with the same HP rating can have vastly different torque ratings depending on the type of motor and how it is assigned it’s HP rating. For example, Skutt’s continuous duty, 1/3 HP rated motor has more torque than other leading brands ½ and even 1HP models. For more information on wheel motors and power click here. 

Manufactures generally do not publish torque ratings primarily because there is no industry standard for such a measurement. This again is a good time to ask your clay supplier for advice. Chances are, if the wheel can handle the amount of clay shown in this photo, it will certainly meet your needs. 

Fit and Weight 

When we talk about “fit” we are simply talking about how comfortable you feel while throwing. Is it the right height? Do your legs fit comfortably around it? Where are your arms going to rest while throwing? The best way to find this out is to visit a distributor showroom and actually sit behind one. 

The weight of the wheel can also play an important role in how the wheel feels. Some people prefer a heavier wheel so they can use it as a brace with their legs when centering clay. Others may need to regularly move their wheel or even transport it to places other than their studio. If this is the case you may want to consider a model that is smaller or lighter. 

Noise 

Wheel noise has probably received more attention than it deserves. This attention is more a product of marketing campaigns than reality based. The bottom line is most commercial wheels on the market today are very quiet. If the quietest motor is your only criteria, you may be sacrificing other important factors like torque. 

Some potters actually prefer the wheel to make a little sound as it gives them an auditory sense of the speed of the wheel head. Normally, if a wheel is making too much noise, something is wrong with the bearing or the motor. 

The SSX controller offered by Skutt as an upgrade will significantly reduce the sound produced by the wheel motor but its primary function is to provide smoother transitions in speed especially at low RPMs.  

Unique Product Features 

Every manufacturer offers their own set of unique features that define their brand. For example, Skutt wheels are the only wheels that come standard with an easily removeable wheel head that makes cleanup so much easier. This design also allows them to use a one-piece splash pan that will never leak and can easily be taken to the sink for cleaning or transport your trimmings without having to empty them first. For information on other unique features click here.

Customer Service and Warranty 

Most people do not think of service or warranties until they actually need them. Ask around to see which companies offer the best service. There is nothing more frustrating than having to go through endless phone prompts and not being able to reach an actual person. 

Research what your warranty actually covers. Some warranties seem like a good deal but when you read the small print, you are left holding the bag any many cases. Skutt is one of the few companies that will not only cover the replacement part, they also cover the labor to install it which is often times the biggest expense. Be wary of companies that prorate their warranties in the small print.

Skutt was recently able to increase its warranty period to 10 years based on the implementation of new longer lasting technology in the foot pedal.

Ready to start seeing your options? Check out Skutt’s collection of pottery wheels, and use our pottery wheel distributor locator to find where to buy a wheel closest to you. 

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If you own a Skutt Kiln with a KilnMaster Controller you may only be using a fraction of the features available to you. Some of the coolest features are accessed while the kiln is firing. We call these Hot Keys. Most of these give you diagnostic information that is helpful troubleshooting your kiln or just gain better insight into the actual performance during the firing. Below is a list of the Hot Keys and their functions on newer KilnMaster Controllers (ones with green display lights):

1, 2 and 3

These keys will display the temperature reading of the corresponding thermocouple on a Zone Control Kiln. Zone Control is an optional upgrade available that places a thermocouple in each section of the kiln. This allows the controller to sense when one section of the kiln is firing too hot or too cold and make adjustments during the firing.

In a 3 section kiln, the one key will display the temperature in the top section, 2 will display the middle, and 3 will display the bottom. The controller must be configured for Zone control for these keys to work.

5

The five key will display the programmed rate of rise in degrees per hour for the active segment in the program.

7

The seven key will perform an Amp check and then continue the firing. It will temporarily stop the program, turn each relay on individually and give you the amp reading. Once all the relays have been cycled on it will continue the firing. A list of the desired amp readings for each model can be found under the Library tab on the Skutt website under troubleshooting.

Each Amp reading represents a section of the kiln starting from the top. If your kiln only has two sections the 3 reading will be zero. If one of the sections that does exist comes back with a reading of Zero, chances are likely you have a relay out. If it is reading low, it may be an indication that your one or more of the elements in that section are starting to wear out. It is a little more complicated than that so if you want a complete description on how to accurately interpret the results read the white paper on Interpreting Diagnostics under the Library Tab of the website.

8

The eight key will flash 3 decimal points representing the outputs on the control board. The outputs are what tell the relays to turn on. The one on the left will represent the top section of the kiln, the middle represents the middle section and the one on the right represents the bottom section.

This is a very complex troubleshooting tool and almost always needs to be used in conjunction with other tests to gain useful information. Most likely this test will be initiated at the request of a Skutt Technician.

0

The zero key will tell you the elapsed time since the kiln was started. This can help you estimate when to be there for the ending of the program.

View

The View key will tell you what segment of a program the controller is currently running. It will also tell you what we call the “traveling set point” and the temperature of the circuit board. The traveling set point is the temperature where the kiln is supposed to be if it were keeping up with the program.

Just because you program a kiln to fire at a particular rate to a temperature does not necessarily mean it is capable of achieving that rate. It will only do the best it can. This diagnostic feature allows you to see the actual performance. Again this feature requires advanced troubleshooting skills to extract meaningful data and will most likely be interpreted by a Skutt Technician.

The Board Temperature is a very useful in determining if your kiln room is properly ventilated. It’s kind of hard to believe that the room temperature could have much impact on the temperature of the circuit board when it is sitting so close to a kiln chamber that is 2350F, but it does.

If the board temperature reaches 160F the kiln will shutoff to avoid damaging the controller. We calculate that if the room air exceeds 100F while the kiln is firing you run the risk of getting an “E-bd” error and the kiln shutting off. Often times a fan blowing on the controller is enough to prevent this from occurring.

One last feature accessed through the view key is “skip step”. This will advance any program to the next segment in the program. To activate skip step press View then ENTER and ENTER again.

Review

Review is generally used prior to pressing Start to ensure you have entered the correct program but it can also be pressed while the kiln is firing just in case you are second guessing yourself (or someone else who may have programed the kiln).

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