PeterH

Two ideas you may find useful.
1) Stain the cracks to make them more visible (you may have more than you think).
2) Use a thermal stress-test to make "latent" cracks appear sooner.
... one from Digitalfire https://digitalfire.com/test/iwct
 
 

Found the image below on her book of faces page. Maybe u.g. on the slipcast textured blanks then wiped, sanded  or scraped down?

Textured clay, black , colour, sand down bumps leaving white?

Not saying this is her method but I think I would just texture the clay and paint the designs with underglaze. Clear glaze over the top might even get me some minor movement especially if sequenced to encourage.

Where there is a very slight difference in COE, a thicker glaze might show a crack where a thinner layer wouldn't (depending on some associated factors...).
COE is fundamental to combating crazing!
Materials expand and contract as they heat up and cool down, respectively.
Where clay and glaze expand and contract at rates that are different (enough), problems happen!
At one extreme, bits of glaze pop off the work, shivering, and at the other extreme, the glaze cracks, crazing.
Crazing can be ameliorated by changing the glaze formulation/composition, also by using a different clay.
You'll hear and read the term "fit" and "glaze fit" - where the glaze "fits" the clay, there aren't shivering or crazing problems.
Here's links to some articles:
Co-efficient of Thermal Expansion (digitalfire.com)
Glaze Crazing (digitalfire.com)
...and a few threads from this Forum:
Crazing Clear Glaze - Clay and Glaze Chemistry - Ceramic Arts Daily Community
Crazing question - Clay and Glaze Chemistry - Ceramic Arts Daily Community
The cracking depicted in the OPs image (first post, above) seems a special case to me - typical crazing forms a pattern, where a large pattern indicates a closer match than a fine pattern. I'm curious to know if the clay is cracking, or is it the glaze?

Weight if dry ingredients are involved.
But volumetric mixing (of made-up glazes) for test-tiles is a great idea ... providing you use a syringe with a decent scale.

@Jmvelezz Finally ...
Transformation of Six Leaves Glaze to Contemporary Ceramic Bases on the Taoism Characteristics
http://ithesis-ir.su.ac.th/dspace/handle/123456789/2977
... click on  60155902.pdf near the bottom of the page.
... which seems to be link to  http://ithesis-ir.su.ac.th/dspace/bitstream/123456789/2977/1/60155902.pdf
... which looks like the same link that doesn't work when you use it directly!
I've not found any English-language page at the university that would let me report the problems to the universities IT department. I suspect that they have got their permissions in a twist.
PS You may want to remove the watermark before printing. How to do it depends on your system. Start with a google for something like print pdf without watermark. Don't have the file any more, but think I uncompressed the pdf file then edited it directly (on Linux possibly using pdftk & vi).

If your piece is sculptural or decorative, there’s no problem with using your non-yellowing varnish. 
While I’ve seen some instances of copper washes or copper based raku glazes re-oxidize and change colour over time, they don’t fade.  I’ve not seen it happen with iron based pigments however.
Worth noting that raku artists who know about this phenomena will varnish their pieces to prevent it. 

A little googling if it's of any help.
This seems to be the video, and readers comments about the email address being non-functional.
https://www.youtube.com/watch?v=VC0QXALQT_M
A discussion
https://cone6pots.ning.com/video/home-made-slab-roller
Another users experiences
http://mudismymedium.blogspot.com/2012/04/slab-roller.html
... which comments on the non-functioning email & web references, and gives
https://www.biggovtsucks.com/docs/SlabRollerModified.pdf
https://www.biggovtsucks.com/docs/SlabRollercuttingchart.pdf
Good hunting!
PS A thread on a different DIY roller, with some comments that seem relevant.
 

If I remember correctly there is a video somewhere of making a Vertical slab roller also, 
best,
Pres

Hi colormek8art,
Welcome to the Forum!
Wow, that kiln looks to be in good shape.
While waiting on responses, could you confirm the phase requirement; is it three phase?
Also curious, what are the amperage and max temp ratings?
To test/run safely, the wiring must be proper.
The max temp rating could be important; what temperature target/range do you work in?

... or perhaps not.

Electroplating vs Electroforming: What’s The Difference?
https://facfox.com/docs/kb/electroplating-vs-electroforming-whats-the-difference

Electroforming
https://en.wikipedia.org/wiki/Electroforming
The process involves passing direct current through an electrolyte containing salts of the metal being electroformed. The anode is the solid metal being electroformed, and the cathode is the mandrel, onto which the electroform gets plated (deposited). The process continues until the required electroform thickness is achieved. The mandrel is then either separated intact, melted away, or chemically dissolved. ... my emphasis
PS Note that when the form is to be separated from the mandrel it is advantageous if the electro-deposited layer is only weakly attached to the mandrel. For electroplating strong adhesion is desirable.

If you find a potential image is there any way of getting a preview of how it will look when fired as a transfer (which will typically have a different resolution and pigment model)?

Sounds like a lovely idea. I think, though, that pot making and landscape painting are not often found in the same person! 
Assuming you have a few local artists who already do plein aire paintings of your area, you could ask if they would give permission to use their images for a limited edition run of ceramic decals that a local, or even an Etsy-sourced potter could apply to their dinnerware. (Be sure to also get some practice, generic decals for the potter’s firing calibration tests, for best possible results.)
Alternatively, there may already be images of your favorite areas that do not require copyright to reproduce.
I think there have been several references to ceramic decal makers in past posts, but an internet search should lead to Custom Ceramic Decal Maker. 
 

Tough question!
Parian* is generally defined as a "self-glazing porcelain" which appears to have nearly zero absorption.
How are you using Parian?
Do your finished wares absorb water, at all?
 
*Composing a Workable Parian Clay Body (ceramicartsnetwork.org)

Example of cobalt concentration vs depth of colour
Cone 6 Ultramarine Cobalt Blue Glaze (Glossy Clear plus Cobalt Carbonate)
https://www.thestudiomanager.com/posts/cone-6-ultramarine-cobalt-blue-glaze-glossy-clear-plus-cobalt-carbonate

Tst
... but it doesn't have the cyan-ish tinge.

No, I think my math. Assuming 8”round prox. 20.32 cm so area should by 3.14x((20.33/2)^2 ) = Prox 324 sq cm. So 22W (from above)/ 324= ..068W per sq cm. A bit more than your floor heater ought to melt ice off your mirror as opposed to heating a floor to comfort temps.. I think you are in range and my quick calcs are wrong above.
All done flipping back and forth on this iPad, but seems right. Someone should triple check all the calcs if the OP does want to do this in some fashion, I think we can sneak up on a real potential load.

Looks like Cobalt Carbonate price has dropped recently!
Petalite price hasn't...

Example of cobalt concentration vs depth of colour
Cone 6 Ultramarine Cobalt Blue Glaze (Glossy Clear plus Cobalt Carbonate)
https://www.thestudiomanager.com/posts/cone-6-ultramarine-cobalt-blue-glaze-glossy-clear-plus-cobalt-carbonate

Tst
... but it doesn't have the cyan-ish tinge.

Just another data point: electrical heating film for underfloor or sauna heating @ 440w/sq meter.  https://tinyurl.com/2abs2xdf
Didn't quite believe the difference in the wattage figures, so checked my maths.

The rather large difference maybe related to the speed of response required?

Thanks Peter - the 1% cobalt is close. Agree with you that a little more green needs to be added to get a blue closer to cyan. A good starting place though. May throw the question over to Glazy. Perhaps an Italian potter knows the formulation. I have Londi's bio, which I haven't read yet - may provide a few clues. Will report back if I nail it.

A picture showing the inside of one of the busts might help. Even better if there is something like a ruler in shot to give the scale.
Either posted here or on your website.

The density of snow varies significantly. I kind of really liked the heated mirrors above  for approximate established data. I think we really need more of a description as much as practical as the mounting and what it is mounted to could significantly affect the required energy as well. Gotta start somewhere so maybe size, mounting, materials ….. Maybe a display case in the end is practical.

First a few caveats.
1) As you ask what is the diameter of the wire I assume that you haven't got it yet. If so, why use expensive nichrome when you are operating it at such a low temperature? Oxidation of the conductor isn't going to be an issue, so nichrome's big selling point doesn't apply.
2)  At the temperature you mention the wire looses heat  mainly through conduction and convection rather than radiation. These are very dependent on the (changing?) surroundings of the wire. 
3) The amount of heat required to melt snow off the wall (I'm assuming the fabric is inside the wall) may significantly exceed that required when the outside conditions are dry. Do you have any guestimate of the weight of water that might need to be unfrozen? (It takes about 0.1 Kwh to melt 1Kg of ice once it's at 0C.)

4) While it still needs careful engineering, I suspect that a thermostat-based solution would handle the wide range of conditions better.
Then a reference from the Electrical Engineering section of a Q&A site
How do i find nichrome temperature
https://electronics.stackexchange.com/questions/84516/how-do-i-find-nichrome-temperature
... I rather go with the second answer
You can't. Sorry.
The temperature of the wire depends not only on the electrical power on this wire, but also on the ambient conditions - i.e. how the heat is dissipated. This way, the temperature of the wire will not be constant in time, but will change depending on the air temperature and movement, materials that are in contact with the wire and so on.
In order to make the temperature constant you will need to make the ambient conditions pretty stable, or to use temperature regulator that to regulate the electrical power on the wire in order to get the same temperature in different conditions.
As long as the theory behind such phenomenons is too complex, the calculations are actually possible, but very complex. In most cases, experimental way is much more reliable and useful.
Simply use regulated power supply and change the wire current until the temperature becomes what you need. But always remember that in other conditions it will be different.
PS I see that StackExchange have tags that direct heating questions to interested readers. Maybe posting there would give you a better answer.
https://diy.stackexchange.com/questions/tagged/heating
https://diy.stackexchange.com/tags/heating/info
I've almost no personal experience with StackExchange, other than it's software section which is always informative.

First a few caveats.
1) As you ask what is the diameter of the wire I assume that you haven't got it yet. If so, why use expensive nichrome when you are operating it at such a low temperature? Oxidation of the conductor isn't going to be an issue, so nichrome's big selling point doesn't apply.
2)  At the temperature you mention the wire looses heat  mainly through conduction and convection rather than radiation. These are very dependent on the (changing?) surroundings of the wire. 
3) The amount of heat required to melt snow off the wall (I'm assuming the fabric is inside the wall) may significantly exceed that required when the outside conditions are dry. Do you have any guestimate of the weight of water that might need to be unfrozen? (It takes about 0.1 Kwh to melt 1Kg of ice once it's at 0C.)

4) While it still needs careful engineering, I suspect that a thermostat-based solution would handle the wide range of conditions better.
Then a reference from the Electrical Engineering section of a Q&A site
How do i find nichrome temperature
https://electronics.stackexchange.com/questions/84516/how-do-i-find-nichrome-temperature
... I rather go with the second answer
You can't. Sorry.
The temperature of the wire depends not only on the electrical power on this wire, but also on the ambient conditions - i.e. how the heat is dissipated. This way, the temperature of the wire will not be constant in time, but will change depending on the air temperature and movement, materials that are in contact with the wire and so on.
In order to make the temperature constant you will need to make the ambient conditions pretty stable, or to use temperature regulator that to regulate the electrical power on the wire in order to get the same temperature in different conditions.
As long as the theory behind such phenomenons is too complex, the calculations are actually possible, but very complex. In most cases, experimental way is much more reliable and useful.
Simply use regulated power supply and change the wire current until the temperature becomes what you need. But always remember that in other conditions it will be different.
PS I see that StackExchange have tags that direct heating questions to interested readers. Maybe posting there would give you a better answer.
https://diy.stackexchange.com/questions/tagged/heating
https://diy.stackexchange.com/tags/heating/info
I've almost no personal experience with StackExchange, other than it's software section which is always informative.