PeterH

I remember seeing several "iron wire and golden thread" pots in the Percival David museum years ago, and they formed a lasting impression.
A couple of weeks ago I noticed that a crackle pot that I probably made in the 1980s had developed a significant number secondary cracks. But these cracks only visible when looking hard from a foot or so.  So I've been wondering if I should stain these secondary cracks with a brown "Indian ink". Although I'm not certain that the primary cracks are bold enough to give a good end result. 
PS From p585 of Ceramic Technology by Rose Kerr and Nigel Wood (Volume 5 part 12 of https://en.wikipedia.org/wiki/Science_and_Civilisation_in_China)
Perhaps the best evidence for the contemporary appreciation of crazing in Kuan and Ko ware is the occasional practice of staining the major glaze-crackle with an intense black pigment to provide a network of fine black lines on a smooth light ground. By necessity, this would have happened soon after the firing, and most probably when the wares were still hot from the kiln, when the craze lines were relatively open. Ceramics can continue to craze for days, or even for years, after firing,and this secondary crazing system often appears as a finer network on Kuan wares, between the major crackle lines. This secondary crazing is often stained a lighter colour, perhaps deliberately or perhaps simply through use. These two crazing systems supplied the celebrated "gold thread and iron wire" effect, so often admired in Kuan and Ko wares.  How the fashion for staining the crackle began is not known,but one possibility is that it was first used as a `rescue' process, designed to improve the appearance of accidentally oxidised pieces.

The software I'm using (Glazemaster) calculates COE 6.52 for that glaze, which, if all things were equal, would craze on some of the clays I've tried (and no longer use...), and maybe craze on one or more that I use now.
However, all things aren't equal!
My understanding is that:
  a) calculated COE is especially helpful when adjusting a recipe, where the ingredient ratios are adjusted, and/or a new ingredient is introduced;
  b) calculated COE is less helpful for comparing glazes that have radically different ingredients/recipes, where a glaze with a lower number may craze more than one with a higher number.
My own experience supports both notions.
I'd started over several times in my quest for a well-fitting clear.
The sodium and potassium were lowered, and lowered again; talc was raised, and raised again; lithium was introduced - via petalite, close, a bit more talc, a smidge more petalite, voila!'
I've posted the recipe here somewhere; if you're interested, OP, shout. No guarantee it would work with the clay in question! GlazeMaster calculates COE of 5.31

I remember seeing several "iron wire and golden thread" pots in the Percival David museum years ago, and they formed a lasting impression.
A couple of weeks ago I noticed that a crackle pot that I probably made in the 1980s had developed a significant number secondary cracks. But these cracks only visible when looking hard from a foot or so.  So I've been wondering if I should stain these secondary cracks with a brown "Indian ink". Although I'm not certain that the primary cracks are bold enough to give a good end result. 
PS From p585 of Ceramic Technology by Rose Kerr and Nigel Wood (Volume 5 part 12 of https://en.wikipedia.org/wiki/Science_and_Civilisation_in_China)
Perhaps the best evidence for the contemporary appreciation of crazing in Kuan and Ko ware is the occasional practice of staining the major glaze-crackle with an intense black pigment to provide a network of fine black lines on a smooth light ground. By necessity, this would have happened soon after the firing, and most probably when the wares were still hot from the kiln, when the craze lines were relatively open. Ceramics can continue to craze for days, or even for years, after firing,and this secondary crazing system often appears as a finer network on Kuan wares, between the major crackle lines. This secondary crazing is often stained a lighter colour, perhaps deliberately or perhaps simply through use. These two crazing systems supplied the celebrated "gold thread and iron wire" effect, so often admired in Kuan and Ko wares.  How the fashion for staining the crackle began is not known,but one possibility is that it was first used as a `rescue' process, designed to improve the appearance of accidentally oxidised pieces.

I believe the image in the first post is a work by Yō Akiyama and is from his work using stoneware, heat and peeling off layers of clay to achieve the cracks.  If you search his name you can find many examples of his work.
From this Wikipedia link:
"Akiyama developed and fine-tuned the latter technique in the 1980s while experimenting with the feasibility of peeling the outer skin off a ball of clay, in the same way that one might peel a fruit. To achieve this, he heated a ball of clay with a gas burner, creating a shape with a soft center and a hard, outer shell. Since that first experiment, Akiyama has refined his technique and manipulated this template to create a multitude of cracks and chasms on the surface of his pieces, in some cases completely inverting the shape."
 
 

A couple things:
plaster - if mixing 70-100 results in a thick mixture, and you only mix for 2-3  minutes, its likely you have old plaster. Adding more water helps with the pour but it will result in soft plaster. (Also takes longer to set up.) New plaster would be a good start.
slip - If you don't know if, or what, deflocculant was added to the clay before you purchased it, it may be best to first attempt to make a slip with a decent flow. Add enough water to get a decent flow and let the mix sit overnight. See how much it thickens overnight. In the morning add some more water if it needs it. 
Its been my experience that if the slip is over deflocculated it will gel up in the mold no matter how thin you mix it. 
If the slip has too much water you will mostly get an extremely thin casting. I've never gotten a lumpy pour with too much water. Lumpiness is mostly a case of deflocculation issues.
Mold soap - did you allow the soap to dry before pouring the plaster? If it was still wet it could seal the surface of the plaster and slow the absorption of water.
Laguna Clay sells their B-mix in a powder form in a "Casting" version. They list the recipe on their website. What their website does not indicate is that the "Casting" version also contains the dry form deflocculants, soda ash and barium, already mixed into the dry powder. 

Changing the mesh size of the silicon carbide apparently influences the appearance.

PS I suspect that refiring can only smooth/collapse/consolidate previously fired lava glazes, as all their fizz was expended in their first firing.
As the top half of the cylinders indicate thicker application of the glaze increases the foaming -- especially for finer grades of SiC.

+1 ... but I failed to find the extract on cracks.
In case it isn't just my finger trouble, here is an extract from an earlier posting
http://ceramicsfieldguide.org/pdf/materials-handouts/ClayCracks.pdf

Changing the mesh size of the silicon carbide apparently influences the appearance.

PS I suspect that refiring can only smooth/collapse/consolidate previously fired lava glazes, as all their fizz was expended in their first firing.
As the top half of the cylinders indicate thicker application of the glaze increases the foaming -- especially for finer grades of SiC.

There are a myriad of reasons pieces can crack. Forming methods, trimming methods, drying methods, firing methods, glaze reasons, cooling methods and so forth. The go to resource for tracking down and determining why a piece cracked is Frank and Janet Hamer's book The Potter's Dictionary of Materials and Techniques. It is well worth purchasing and comes highly recommended by many people. You can see a snippet of the book and the relevant section on cracks in the link below.
There are over 30 scenarios for cracks.
https://books.google.ca/books?id=TApnGTVLwxAC&pg=PA86&lpg=PA86&dq=hamer+and+hamer+cracks&source=bl&ots=inS6KQPb4N&sig=ACfU3U3-WW9HznLwIEytHMyGanL2bpymZA&hl=en&sa=X&ved=2ahUKEwiG1JCB0KPgAhWyPH0KHX7EBo4Q6AEwB3oECAcQAQ#v=onepage&q=hamer and hamer cracks&f=false

Changing the mesh size of the silicon carbide apparently influences the appearance.

PS I suspect that refiring can only smooth/collapse/consolidate previously fired lava glazes, as all their fizz was expended in their first firing.
As the top half of the cylinders indicate thicker application of the glaze increases the foaming -- especially for finer grades of SiC.

Changing the mesh size of the silicon carbide apparently influences the appearance.

PS I suspect that refiring can only smooth/collapse/consolidate previously fired lava glazes, as all their fizz was expended in their first firing.
As the top half of the cylinders indicate thicker application of the glaze increases the foaming -- especially for finer grades of SiC.

Changing the mesh size of the silicon carbide apparently influences the appearance.

PS I suspect that refiring can only smooth/collapse/consolidate previously fired lava glazes, as all their fizz was expended in their first firing.
As the top half of the cylinders indicate thicker application of the glaze increases the foaming -- especially for finer grades of SiC.

Changing the mesh size of the silicon carbide apparently influences the appearance.

PS I suspect that refiring can only smooth/collapse/consolidate previously fired lava glazes, as all their fizz was expended in their first firing.
As the top half of the cylinders indicate thicker application of the glaze increases the foaming -- especially for finer grades of SiC.

Changing the mesh size of the silicon carbide apparently influences the appearance.

PS I suspect that refiring can only smooth/collapse/consolidate previously fired lava glazes, as all their fizz was expended in their first firing.
As the top half of the cylinders indicate thicker application of the glaze increases the foaming -- especially for finer grades of SiC.

If the kiln was fired to cone 4 then for a typical bisque firing this was way too hot. Common bisque cone is 06 - 04.
Common cone numbers go from 022 up through 14. The zero in front of cones 022 up to 01 is very important. There is a big difference between a typical cone 04 bisque and a cone 4. Cone 04 will leave the pots porous enough for glaze to easily stick to it, cone 4 is nearly at the maturity level, this is why the glazed pot fused to the bisque piece that was on top of it. 
It's difficult but not impossible to glaze overfired bisque. Try warming the piece up in the oven then dipping it in the glaze. Brushing glazes go on easier but each coat will take longer to dry. It might be easier to remake the pots rather than try and glaze them.
edit: I wouldn't fire a bisque piece on top of a glazed piece even at cone 04. Some glazes start to flux (melt) enough at cone 04 that they could still stick to a bisque piece.

Perhaps this video, which you mentioned in an earlier posting.
http://mcgyakimono.blogspot.com/2010/08/making-teaware.html
PS Thanks for so many memorable postings.

Perhaps this video, which you mentioned in an earlier posting.
http://mcgyakimono.blogspot.com/2010/08/making-teaware.html
PS Thanks for so many memorable postings.

Perhaps this video, which you mentioned in an earlier posting.
http://mcgyakimono.blogspot.com/2010/08/making-teaware.html
PS Thanks for so many memorable postings.

Sorry, but yet another update that I hope helps anyone else that goes through the headaches I have gone through with this clay body.

So, all of the suggestions in this thread did help, the wedging, the compression direction (slow drying vs not) etc but I still found I was getting a 5-10% crack rate. Very minor, never through, but nonetheless present.

That said I have gotten this to 100% success rate adding a few more steps into my routine so I hope this helps.

First off, as many have mentioned, lets assume you have consistent thickness in your bottoms and forms, wedged well. From there two things seem to be the game changers for me. Instead of just compressing out > in, it seems the clay really loves to be forcefully spread in > out, then forcefully out > in. Take your time with this, I start my forms with a rather thick bottom and by the time I am done really compressing in both directions it is the right thickness. The last thing I do is when the pots are leather hard, if not a bit before, is use a tool of some sort, a spoon will work, a sponge stick, your finger, whatever....and compress manually outward in with said tool. With these two additions I have fired over 200 mugs with zero cracks.
When I say forcefully above I mean really forcefully. The way I came across this was by making some plates, which I laughed at while making, thinking of coarse a plate would crack. When I make plates I use a ton of force with my fist getting it wide, then compress in to even the surface…wouldn’t you know it, no cracks.

Hope this helps to those dealing with this in the future!

I expect you are right that it doesn't contain any "smarts" for minimising the effect of failing elements.
PS What information I found (but haven't read in detail)
I think that the CE is just an indication is passes European community standards
CE marking for Electronic equipment - EMC testing
So your controller is probably a Stafford ST316B.



 
Data sheet, installation guide and user guide at https://staffordinstruments.co.uk/st316b-controller/
Site https://staffordinstruments.co.uk/
Contact https://staffordinstruments.co.uk/contact-us/

I expect you are right that it doesn't contain any "smarts" for minimising the effect of failing elements.
PS What information I found (but haven't read in detail)
I think that the CE is just an indication is passes European community standards
CE marking for Electronic equipment - EMC testing
So your controller is probably a Stafford ST316B.



 
Data sheet, installation guide and user guide at https://staffordinstruments.co.uk/st316b-controller/
Site https://staffordinstruments.co.uk/
Contact https://staffordinstruments.co.uk/contact-us/

Do you want/need the inside of the tube glazed?
Would some sort of bellows help you blow out the glaze -- e.g. an air-filed glaze trailer.
Pipe cleaners, or a more durable equivalent such as:
5 x Straw Cleaning Pipe Cleaners kit, Bristle Metal Pipe Cleaner for Drinking Straws, easy to brush and clean pipes, Pipe Cleaner Kit, Straw Cleaner Brush and kit for craft supplies
https://tinyurl.com/5ftme7n7

 

It depends.....  Some people are heavier appliers than others.  Commercial glaze usually says apply 3 coats.  I have seen people apply three coats that look like my 1 coat, and others whose 3 coats would puddle all over the kiln shelf.
At our community centre, I get newbies to do a "number of coats" test tile, before they do any glazing or underglazing.  A square tile of clay, marked into 4 smaller squares.  Corner 1 gets one coat of underglaze, corner 2 gets 2 coats, corner 3............etc
This gets bisque fired and then they apply 1 coat of clear on half of corner 1, 2 coats on half of corner 2..........
Second fire to earthenware, (we don't do any high-fire) then they (I) can determine if they are a light applier or a heavy applier.  This gives them a guide for future applications.    
We often repeat with a vertical tile with texture.

@PeterH Copper Oxide gives me dark specks. The carbonate is much more finely milled and gives a more uniform colour
@Min good to know. I might go the non cadmium green and mix it with black and a pinch of blue to get a more emerald green. I’m too scared of poisonous cadmium!

Useful reference
Amps vs. Volts vs. Watts vs. Ohms: What’s the Difference?
https://www.familyhandyman.com/article/electrical-terms-explained-watts-volts-amps-ohms-diy/
... with a good summary