Babs

Some time ago I posted about challenges with wollastonite clumping.  I have now found a process which is helping with this issue.  I utilize one of these flour sifters when weighing out the wollastonite.
  I sift the material directly into a pan on the balance until I have the necessary amount.  It's pretty low tech, but it works.  Perhaps not feasible for large-scale batches, but I'm usually making 1-2kg batches of most of my glazes, and it works fine for that.
 

Couple of areas where clay can be sensitive to fast heating, also slow at start, or even candling if you not sure of moisture content  and clay thickness. Some folk hold somewhere around 700-800 °C to drive off xhemically bound water but if you havent had to up until now, I wouldn't start.
Let's know how you go,centainly save on energy and time.

i have not read this entire post but would like the original poster to consider spraying glaze to avoid disturbing the underglaze.
a very simple siphon sprayer costs about $30 and is branded EZsprayer.  it is very fast and a kiln load, big kiln, can be done in an hour or so depending on how many colors you use.
just a thought.

Thanks @Babs! Assume this is to have a slow start/ avoid shock/sudden high temp - is this right?
Will def. give a go

Run it up as you would for your normal bisque i.e.the same ramps  until I'd say
600°C then proceed as for your normal glaze firing ramps to goal temp/ cone.
 
 
 
 

I believe that recommendation is to prevent the material from getting into the element grooves. I don't think that switching to another material is necessarily any better in that regard. If you're going to do it, use the material that works the best which would be silica sand, and just be sure not to get any into your elements, and vacuum them out after firing.
There is very little shrinkage in a bisque firing, so it's more about even heating/cooling and/or expansion/contraction during the heating/cooling.

when wondering around the property this week I notice a rotting stomp of a large pine tree that was blown down a few years ago; the dried yellow clay still on the bottom of the stomp was simular to the color of the plastic cat litter buckets;  the clay on the stump contains iron oxides.  Long ago while solving problems for plastics, fine particles of iron oxides were used to produce colors to the plastics.  
My point is you should think about the iron being taken from the plastic.  Test using a plastic bucket that is not yellow.  
LT

Hi and welcome! I wish it was under better circumstances.
The pictures are worth a thousand words, and thank you so much for including those!
The fact that the piece is broken so cleanly, and in 2 near-perfect vertical lines all the way through means that this wasn’t specifically your clay, or anything you did during building the piece. It’s a nice dense clay  that probably stuck to the kiln shelf due to the mass and size of the piece, and cracked during cooling. For the next pieces, I’d fire them on some sand/alumina so that the piece has the equivalent of little refractory ball bearings to shift around on. You could also use a waster slab that will shrink at the same rate as the piece, but take the brunt of the force and absorb the crack instead.
If the clay survived the bisque just fine, another possibility is to not fire the piece to full clay maturity. Porosity in the end piece is less of a concern for you than it would be for someone throwing functional ware.

Bloating for sure is caused by overfiring but then there is also blebbing.
I think that in the last 20 years or so the term bloating is used to cover both bloats and blebs  but with pyroplastic claybodies, such as many of the smooth white bodies, an air bubble within the clay wall will expand during glaze firing when the glaze has melted enough to seal the surface of the clay and the air pocket expands causing a bump on the surface of the clay. These don't show up during the bisque but do show up during the glaze fire, does't have to be overfired to happen.

I'm afraid I kind of agree with BlueBird. If it has half dollar size holes in it due to corrosion, the rest of it is probably not structurally sound.
The non-pugmill option is to simply not wedge and not recycle. Most clay bodies are good to go for throwing right out of the bag.
I switched to slab building about a year ago after 30 years of throwing, due to bad arthritis in my hands. Gotta say I don't really miss throwing. I'm happy to still be working with clay, and the challenges and possibilities of working with new techniques have me more excited about ceramics than I have been in a long time.

There are other cost savings with firing to lower temps besides just the cost of electricity, big time if you're firing to cone 10 in the electric kiln.
- Extended element life. Firing just 04 will give you 2-3x the element life versus glazing at 5/6, double that vs cone 10.
- Longer kiln life
- Longer kiln furniture life
- Less energy removing excess heat from the studio (if you're running AC or fans)
Plus you can increase output with shorter firing schedules, and it's better for the planet.

A credit card, pinking shears, and some nice gloopy slip did this. 

Old credit cards make good bench-scrapers and ribs. They can be cut into any profile  needed for shaping and trimming pots, smoothing seams and surfaces. Notching the edges of the card will give you many kinds of texture possibilities. 

We call that color ‘snot red 

No reason you can't put the water into the old glaze bucket to start with. I agree with sieving once unless you have a specific reason for doing that.

This one from my students. If you manage to wear the skin off your pinky, vet wrap is a good way to protect it. 

I've taken to using the web between the pointer finger and the next finger to compress lips. No extra reaching!
 
best,
Pres

A thought I’ll share: As soon as I get the powder into the water bucket I put the lid on and go do something else for a while. It lets things get hydrated before mixing, but mostly I do it to reduce dust in the air. 

Were your pots warm when you wiped? If not you may not be getting as much ink in the craze lines.

Just for reference once I reach bisque temp in all my gas Kilns (I have 4)
I usually leave the gas setting alone and just use the damper to contol kiln
no need to micro adjust  gas settings thru a firing past 1800-2000

It's easier to overpower these little round kilns. Sometimes you need to back off the burners to get them to go. Also, what size shelves did you have in the kiln? You usually need to use a smaller shelf than what an electric kiln of that size would use, so there's room for air to flow. A lot of people also put a shelf at the top, like 3 inches below the flue opening. Even a short pipe over the flue will increase the draw. You can even make a small chimney out of stacked soft brick.

Wondering if a  pipe chimney would draw more  air through, and damper needed for sure.
 

You need a damper-I suggets thin broken kiln shelve say 1/2 inch thick so that the weight is minimal -or just a soft brick which is light still
Also I would run as the larger pipe (I thought you said it was 3/4) all the way to kiln. It looks like you necked it down somewhere in last 10 feet with smaller flex? Its usually not a pressure issue with natural gas its a volume issue, so keep the pipe as big as you can to the kiln.
I have those same type of burners on an updraft .  You cannot change your altitude  so you need to have all the other functions perfect 
 

After firing and in situ. :-))

Ok, now download the firing log and feed that sweet thang into @jay_klay_studio's graphing program to visually see the tracks of the 3 sections. And if you really want to have some fun, add another 9999 drop all the way down to 100 after your regularly programmed cool to log how looooonnnggggg it takes for the last several hundred degrees. Several times over the years I've printed the extended graph of a few kilns as a teachable moment for the students of the virtue of patience, i.e., "Can I get my piece tomorrow?" "No, next Friday."