Pres

I just realized that I never came back to reply, and it's super irritating when people do that...
Anyways, I tried working faster and stirring more vigorously, and the plaster set up as usual. Success!
I didn't know that faster stirring made for stronger plaster, so I'll get out the jiffy mixer next time. (I learned to mix plaster in a community college class, so we might have been stirring by hand because it was more practical for a group of people than taking turns with a jiffy mixer.)
Thanks, all, I really appreciate the advice.

Always my key tool with plaster is the jiffy mixer -also drop the bucket hard a few times  to get the air bubble to rise to top  before pouring also is a good tip

Hi B.H., Welcome to the Forum!
Good questions.
Excepting small/test kilns, expect your kiln to be rated for 240v, single phase*.
Also expect to run a dedicated circuit for your kiln.
Firing clays and glazes produces fumes. Adequate ventilation is a must, in my opinion.
To fire cone 8, a kiln rated to at least cone 10 will last better than a lower rated kiln.
There are several archived threads here where some of your questions are discussed at length; I'll look later today, have to run just now!
 
*Not sure what the electric standard/convention is in Southampton.
Here in California (USA) we have 240v single phase at our home. Three phase is typically only found in commercial buildings...

If this is in the UK?  then we need to know more on what the electrical voltage is in the UK. Maybe some UK potters can chine in with this tec info

Only very small kilns will run on 120V service. Any kiln of functional size will need 220/240 volts. The smallest kiln I would consider is an 18" wide model. But ideally a 23" wide model would be the most functional, as you can fit plates and serving bowls in it much easier. First thing to do is to take a look at the web sites of some kiln manufacturers in your area to get an idea of what's out there, and see what the electrical requirements are for the size of kiln you want. Then have an electrician check out your system to see what size circuit your system can handle. Minimum you'll need a 30 amp breaker, on up to 50 or 60 amps depending on the size of kiln you want. At £800 you'll have to buy used, but looking at the new ones will give you an idea of what you'll need to do as far as hooking it up. If the kiln is indoors, it will need to be vented, or at the very least have 2 windows that can create a cross draft with fans.

The OP shows a location in the UK and price limits in pounds. The standard electric service there is 230V. In the US, standard residential electric service is 120/240V, where the normal household receptacle is 120V and other special purpose receptacles are 240V. Thus, in the US, there are a variety of kilns designed for either 120V or 240V service. I don't think there will be any 120V kilns in the UK, but I could be wrong.

I bet they made some small hobby doll kilns and the like in the UK that ran on 120 like they did here

I've had to reformulate over half of our pottery glazes, both cone 6 and cone 10 to accommodate the end of Gerstley Borate, Custer, and Texas Talc. Using frits for GB, Mahavir Potash Feldspar for Custer, and dolomite/whiting for talc. Of course, all of the recipes needed changes to amounts of silica, kaolin, etc.
The tough ones seem to be the recipes that were "breaking" glazes or used some sort of lithium. Those took some tweaking and testing to get to a similar match to the old glazes.
Our local supplier has switched from Custer to G-200EU in their clay body mixes without any noticeable difference.

I have been spending a lot of time and energy replacing my Gerstley Borate glazes. The new ones are coming along, but they just don’t have the same glow and magic. I am trying to push the limits of “how much boron can I get away with?”
The good news is that switching to Fabi Talc in place of Texas Talc has been seamless. 

I have a favorite glaze that uses talc, and up until lately have had quite a bit to use in glazes that I bought several years ago. However this last glaze batch found me with none left. Last year I had heard about  a shortage of talc, and believed I would have to reformulate my glaze to work with a different component, maybe dolomite. Imagine my surprise when I found Fabi Talc listed at SC. So I will be ordering some to use in my glaze. However, it makes me wonder if anyone has had to reformulate glazes or clay bodies due to a lack of materials? 
QotW: Have you had to reformulate any clays or glazes due to a shortage of materials?
 
best,
Pres

The clays I like from "nearby" vendor (about a hundred miles) have been reformulated.
The whitish stoneware seems about the same, the red behaves a bit differently.
My intent was (still is!) to look into alternatives this year; I've enough Gerstley, Custer, and Texas Talc to last a few years, however, years go quickly...

All the time now. Gerstley is gone and Gillespie is not a perfect match. 3134 requires a complete rewrite of the recipe. Custer is gone from the market, but I still have some. G200EU might be ok, haven’t tried it yet. Still have some old Amtal talc, but some Fabi is in my future. What’s next?

I have a favorite glaze that uses talc, and up until lately have had quite a bit to use in glazes that I bought several years ago. However this last glaze batch found me with none left. Last year I had heard about  a shortage of talc, and believed I would have to reformulate my glaze to work with a different component, maybe dolomite. Imagine my surprise when I found Fabi Talc listed at SC. So I will be ordering some to use in my glaze. However, it makes me wonder if anyone has had to reformulate glazes or clay bodies due to a lack of materials? 
QotW: Have you had to reformulate any clays or glazes due to a shortage of materials?
 
best,
Pres

First, why vinegar in the throwing water?
Usually when we see black on the wheel head it is simply a tiny bit of the aluminum abrading from the clay. Could just be the abrasion of the bat against the wheel. Does wiping it down not remove it?

I use a talisman at work, and while it’s great for 10 gallon batches of glaze, it would be wildly impractical in my home studio. The cleanup of the brushes is a pain. 
I have a smaller sieve that sits in a 5 gallon pail at home, and I use a large round sash brush to push the glaze through. It works pretty fast and cleans up very easily. 

@ABlancBest bet here is to assess the kiln problem, fix it, and then re-fire the load to ^6.  Check your elements to make certain none of them has broken first. If they are in good shape, then the problem is probably in the lead boxes. Is this kiln run on a cone setter or a programmable controller?  If in a setter was the cone in the setter still as if unused?
 
best,
Pres

Pack the middle the tightest.
Have you tried just using the cone 08 preprogrammed firing schedule?

Density of the load has an effect on the way heat moves in the kiln. Kilns are heated by 3 different forms of heat transfer: Radiant, Conduction, and Convection.  Understanding these will help you to understand the need to pack the kiln consistently. Radiant heat is occurs first in the kiln as the elements radiate heat to heat up the air and the pottery. The pottery on the outer edges will heat up to radiate heat towards the center of the kiln. Please note that while Radiant heat is going on Convection is also occurring in the kiln as air heats up and begins to move to the top of the kiln forcing cooler air downward. Overly tight loads will inhibit the movement of air in the kiln causing areas that do not get air to not reach expected cones. However, as this is going on Conduction, where heat is moving through a solid, is taking place, Conduction is a slower process but it allows the pots to heat up from the outside to the inside, and the kiln from the inside to the outside. This good reason to have proper distance from the kiln to outside walls or other materials that could ignite.
Hope this helps to answer some of you concerns.
 
best,
Pres

Hi folks, we covered this a few years ago, but I was mixing glazes yesterday with my plastic bucket sieve, and a brush to run the glaze through the sieve into a spare bucket, and then back into the rinsed out original bucket.  I have often wondered about buying a Talisman sieve, but in the long run the cost scares me away, and I really get along fine with my bucket sieve. I will pick up a digital scale as the cost of them has come down.
QotW: Talisman, Bucket or other type of sieve for glaze mixing?
 
bestg,
Pres

Thanks Min, yes it only has 1 thermocouple. I'll make note of this info for my next bisque firing

Density of the load has an effect on the way heat moves in the kiln. Kilns are heated by 3 different forms of heat transfer: Radiant, Conduction, and Convection.  Understanding these will help you to understand the need to pack the kiln consistently. Radiant heat is occurs first in the kiln as the elements radiate heat to heat up the air and the pottery. The pottery on the outer edges will heat up to radiate heat towards the center of the kiln. Please note that while Radiant heat is going on Convection is also occurring in the kiln as air heats up and begins to move to the top of the kiln forcing cooler air downward. Overly tight loads will inhibit the movement of air in the kiln causing areas that do not get air to not reach expected cones. However, as this is going on Conduction, where heat is moving through a solid, is taking place, Conduction is a slower process but it allows the pots to heat up from the outside to the inside, and the kiln from the inside to the outside. This good reason to have proper distance from the kiln to outside walls or other materials that could ignite.
Hope this helps to answer some of you concerns.
 
best,
Pres

Density of the load has an effect on the way heat moves in the kiln. Kilns are heated by 3 different forms of heat transfer: Radiant, Conduction, and Convection.  Understanding these will help you to understand the need to pack the kiln consistently. Radiant heat is occurs first in the kiln as the elements radiate heat to heat up the air and the pottery. The pottery on the outer edges will heat up to radiate heat towards the center of the kiln. Please note that while Radiant heat is going on Convection is also occurring in the kiln as air heats up and begins to move to the top of the kiln forcing cooler air downward. Overly tight loads will inhibit the movement of air in the kiln causing areas that do not get air to not reach expected cones. However, as this is going on Conduction, where heat is moving through a solid, is taking place, Conduction is a slower process but it allows the pots to heat up from the outside to the inside, and the kiln from the inside to the outside. This good reason to have proper distance from the kiln to outside walls or other materials that could ignite.
Hope this helps to answer some of you concerns.
 
best,
Pres

I should add I put my large shallow porcelain sink  and water setup  with high ball valve pipe and hose setup in studio from a salvage yard in 1973.  The sink is shallow but large.That was 51 years ago. Lot of water thru the screens  since then.

I used to use a Talisman but switched over to using a cordless drill with a brush attachment and a regular plastic sieve that sits in the glaze bucket . WAY easier to clean up!!! Can clean the brush attachment in a small basin or pail of water or under a running tap. Takes seconds and no big sink needed. I have one sieve for clear and light coloured glazes and the other for the dark glazes.
I sold my Talisman.
To give credit where credit is due this idea is from @liambesaw

I feel that whatever works for you with slip use that . If it works use it. I will add that in my clay body and calc class back in collage we tested all types of attachments (long before magic water ) and what was leaned that scoring and slip make for stronger bonds. It's a night and day difference  so score and slip . If you are not that you are making weaker bonds.