Piedmont Pottery

At 400c they ought not to be very sintered nor fully dewatered. I. Would bisque them so they end up the same as your established norm. Not very likely all organics are burned out at this point. It may work with some cool result but why risk this load?

I frequently have to fire student pieces that are freshly made and way too thick, and to keep classes on schedule I have to fire them before they have a chance to dry.  I soak at 180F for 10-16 hours before ramping up, depending on the thickness/wetness of the pieces.  The cost of electricity to keep the kiln at 180F is relatively small, and I have never had any student pieces explode.  It is probably overkill to soak that long, but it works, so I'm sticking with it.

I frequently have to fire student pieces that are freshly made and way too thick, and to keep classes on schedule I have to fire them before they have a chance to dry.  I soak at 180F for 10-16 hours before ramping up, depending on the thickness/wetness of the pieces.  The cost of electricity to keep the kiln at 180F is relatively small, and I have never had any student pieces explode.  It is probably overkill to soak that long, but it works, so I'm sticking with it.

My understanding of the physics (fluid dynamics) behind the downdraft vent is that the box under the kiln (L&L calls it the bypass collection box, Skutt calls it the plenum cup) has an opening on the opposite side from the hose connection so that the fan at the output on the far end of the system can pull a significant volume of room air through the box and thus create a venturi effect to draw the kiln fumes down through the holes in the base of the kiln. The L&L collection box has an adjustable "sliding valve" to regulate the amount of room air drawn through the box (thus adjusting the venturi suction across the holes in the kiln base) while the Skutt plenum cup just has a hole. This flow of room air also serves to cool whatever fumes are being drawn out of the kiln and up through the fan. The system does not apply direct suction to the holes in the kiln.
Because air flows seek the path of least resistance, the hole in the pipe of your vent will both increase total air flow at the fan and reduce suction at the base of the kiln when everything is in good condition. However, it introduces the necessary cooler room air at some distance after the fumes leave the kiln. Also, your design with the fan in the middle of the duct run provides the appropriate negative pressure from the kiln to the fan, but applies positive pressure after the fan, blowing the exhaust into the stove hood in hopes that it will be picked up. As Bill notes, this may not work, but also as the duct work corrodes over time (it will, count on it), the positive pressure will blow the stinkies back into the room long before they come out by the stove hood. The design of the Skutt and L&L systems places the fan right on the outside wall of the room so that the whole system remains under negative pressure until being exhausted to the outside. Then, any minor leakage in the duct work will draw air in, not push the fumes out.

Yes, definitely search the forum, references to manuals etc… are many for this kiln. Just something to note, electric kilns rated cone 10 will only make it to that temperature a handful of times with very new elements. Most folks buy a cone ten kiln so they can get about 150 firings at cone 6. In general, Electric kilns and cone 10 work are not the best combination for sure. An old used cone 10 kiln with used elements probably will not make cone 10. 1100 degrees is a long way off so likely part of that kiln is not firing as well. Troubleshooting by measuring element resistances are likely the first best test. Please disconnect the power first!

The most user friendly versions seem to be either Ravenscrag Slip or Alberta slip based, if you’re mixing your own. Ravenscrag can sometimes be interesting to get your hands on in the US, but many suppliers carry Alberta slip. 
Scroll down a bit on this page, and you’ll get the recipe plus firing and application tips for best results.

Your are at three times the length of time, If it does not complete, it’s only bisque, they can be refired.. Crazy idea but if you have a pyrometer you could see if it’s climbing at a slow rate. I assume you do not have one so for me personally, I would switch it off and repair it.

Lots of possibilities here. Start with seeing if all the elements glow when you put them on high for a bit. If a section isn't working, then you'll have to figure out where the power flow is stopping in the system, either in a wiring connection or a switch.
If the bricks are in good condition, then it's generally worth repairing. Chances are it's just one part that is the problem.
If it's in an environment where it could get rained on or be subject to dewy mornings, I would definitely not upgrade it to a digital controller unless you do a wall mounted controller and bring it inside when not in use, however that doesn't help any of the issues with the current system because it would all still be in use as well.

I am overwhelmed by you all taking the time to read my comment and then responding.   Some background information - my great grandmother also suffered from arthritis in the hands and ended up being unable to use them to dress and wash.  The doctor and my mother scared me with stories, so I gave in and sold my wheel but…. I can’t stop thinking about throwing clay, there is something so special about the feel, creating a mug or bowl etc from a wet ball of clay.  I feel like my zest for life has gone. I’ve tried candle making and paying for lessons. But it really doesn’t do it for me - heat wax add fragrances and wick, pour done!  Since reading your comments I feel reenergised and want to have another go. Thank you all so much for your positivity. 

I don’t believe they make 40 amp receptacles or they are uncommon,  50 amp is common. It’s ok for connecting items and wiring to be rated more than they will carry. Not less though else the 40 amp breaker will not protect them and they become the fuse. #6 awg cord is common and fine to be overrated. The cord has conductors next to each other in a confined space so it will heat up more and, it has to remain flexible over its life so good practice for the cord to be sturdy and over rated as well as the plug and receptacle.
 
I like your thinking and would normally suggest if it’s financially feasible for the exact reason you state. Besides it will reduce the voltage drop which puts more power in the kiln and less heating in the wire even if only a minor amount.
You need to get the breaker size right though to protect everything appropriately. Neil mentions the not less than 125% nor more than 150% of the actual kiln load for sizing in North America because electricians often are not familiar.
Since you are running cable, last mention - whether 6/3 or 8/3 mąkę sure it includes an earth ground, JIC it is needed, it is there. For this kiln you need ALL 4 wires.

Does your former clay manufacturer offer any info as to what the claybody you like is made from? Example below of what mine supplies, this isn't going to give you a recipe but it would be a starting place to try and test some possibilities. It is expensive but you could always pay to have an analysis done with a sample of your old clay to give you a chemical analysis like below and then try and work off that.
Do you have access to the same spars and kaolin etc as you used to? What type of clay are you looking to replicate? How much knowledge of materials do you have and do you use glaze calc software?
It might be doable, but chances are whatever you come up with isn't going to be an exact match to what your old clay recipe was. Looking at the analysis of the clay I use below as an example, for the alumina, it doesn't tell you where the alumina is coming from obviously. Some from whatever kaolin and ball clay is in the body plus some from the flux it's using, a tiny bit if there is bentonite in the mix etc. I would have to guesstimate how much ball clay or kaolin is in the mix then work backwards from there filling in the remaining with how much flux (probably nepheline syenite) is needed to give me an absorption figure of the targeted 1% this body has. And so forth for the silica plus fluxes.
Do you mix your own glazes? If so I would be looking to alter those to fit the clay you have access to now.

Great story Mark. 
Coincidentally I brought in a copy of "Clay and Glazes  for the Potter", by Daniel Rhodes, this morning, to introduce a younger employee to the types of books I referenced in my younger days. I asked her if she was familiar with "Alfred" as being the center of the universe, in the pottery world, for many years. She nodded that she heard of it but wasn't familiar with  it beyond that.
It certainly had an impact, on this young potter, from afar. 

I have used iron oxide mixed with water - and some times with a pinch of baking soda - applied to green ware and bisque ware for various clay bodies; firing at Raku temperature, cone 3, cone 5, cone 10-12, wood firing, and electric kilns.  I have never needed the extra melting that a "frit" is supposed to provide.  The amount of water depends on your esthetics.  A little bit can go along way.   I have also made a slip of the clay body and added some iron oxide to apply on the green ware as an surface coating. 
LT
 

I think you want an engobe. You mix the stain, might take a lot, into a slip-like medium that you paint on. When it’s fired, it still will look unglazed, but will not rub off.  

Definite maybe on this.
I would really think about if you want the dust and labor of making clay, it really is a lot of dusty work.
If you only go through a small amount of clay and can mix it up in a 5 gallon / 25L pail then it wouldn't be too bad to do but much more than that and you are probably better using what is available to you and spending the time you would take formulating and mixing a claybody and spend it on glaze testing instead.

Well, I am officially a potter now, sort of. Still a long way to go but the foundation is there. We have a retail store that has done well and I finally left my corporate job to pursue pottery further (and our store). We have a shelf in the store to sell my wares and it does around 1k a month, I know it's not much but that is passive, it just sits there. looking forward to this next chapter in our lives!
My sponge holders have come a long way!

I also think that your customers don’t need the gory details of your pricing formula. Its not that I think we need to lie about things or not be transparent when necessary. It’s that presenting any additional charges, whether it’s adding shipping to checkout or sales tax or credit card fees, is drawing unnecessary attention to something no one really likes. It generates a feeling of misrepresentation when you keep adding things to the price tag, and that can be really frustrating (or worse) for some. I don’t want my customers frustrated, I want them happy so they come back. I don’t want to generate more opportunities for myself to have to smooth ruffled feathers.

Agree 100%! Credit card transaction fees are charged to the seller and should be paid for by the seller. If you're operating a business you should have enough business education to know about COGS (Cost Of Goods Sold). CC fees should be part of those calculations and NOT a method of punishing a certain section of your customer base for using a service YOU are providing. If you don't want to pay CC fees then don't take credit cards. Nuff said.

https://euclids.com/pages/kiln-elements
Euclids will be able to make you some.

Hi Bam,
Tony Hansen's digitalfire.com site has entries on each oxide, including colorants.
Ceramic Oxides (digitalfire.com) and an article on colorants Colorant (digitalfire.com)
I like Susan Petersen's book The Craft and Art of Clay, particularly the glaze section, which includes an entry on each important ingredient (including colorants) and clear discussion of unity.
I use cobalt carbonate, copper carbonate, rutile, tin oxide, chrome oxide, iron oxide, uhm, oh yeah, zircopax.

no, you have some  dry clay stuck on the walls inside the tube.   that creates a ragged lump that forces the damp clay to shape itself around the lump.   if you keep pugging,  and use a little water as you insert the clay, it will start to look like a normal straight pug.  normally,  twice is nice for making the clay exactly the way you want it but when you have this situation, you are gathering tiny hard bits of that dry clay in the middle of the pug. 
keep on and keep calm, it will eventually work its way out.  you might cut the chunks through and feel for small hard lumps now instead of finding them in your thrown walls.  there are no rules saying the first pug of the clay is enough.  it is your very strong  machine, make it do what you want.

Throwing with soft clay is always easier on the joints that stiff clay, arthritis or not. +1 for getting advice from an appropriate and qualified medical professional.

Its plain and simple. You just need a new Dr.

The cortisone may do it but if not its a simple staright froward surgery and I have seen many great outcomes .In terms of arthritis use warm water and keep using your hands to keep them strong. I think your doctor is taking the stay in bed thoght way to far. If you stay in bed life will not hurt you they say until the heart attack .
If you want a real opion go see a hand doctor not a GP
I have had two major hand surgies and have arthrites and large knuckles -no one has said stop throwing-maybe a bit less but move it or loose it is the theme in life. At least mine

Is that the firing schedule you typically use, and this sagging pot was an odd one? If so, then it's probably a thickness issue. Otherwise, it's probably over-firing. That 30 minute hold is adding heatwork equivalent to going another 1.5 cones hotter.