PeterH

Hello Handy,
Not quite sure why this is happening to you. When the "unexpected" happens to me I just roll with it. Rather than try to figure out why this is happening I would simply use this first casting as a "throw away" mold and continue pouring the mold. 
When you pour the second half it will likely go beyond half way and may hold onto the piece. In this case I would take a small trimming tool and carve back the plaster. (to the line you indicated/prefer)
Generally speaking I do not pour molds off clay.  (as the embedding material) If the form is complex I may use clay for that first pour but once plaster is poured I use that as the embedding material. (And discard the piece that was poured against clay.) This way I can more easily control the parting line and create a mold with nice tight seams.

Some eye-candy and tips on slip-cast multi-layer work - but for bone china rather than parian ware.
Multi-Colored Casting in Tempting Transparency
https://ceramicartsnetwork.org/pottery-making-illustrated/pottery-making-illustrated-article/Tempting-Transparency#
Some examples of Sasha Wardell's  work at http://www.strathearn-gallery.com/artists/435/sasha--wardell
PS Can you use setters with parian ware? It might be useful if you could.

I see there is plenty of miscommunication 
1.Tutorials I follow mostly are from Hammerly ceramics and VanTiki on YouTube. 
2. The printed figurine is solid. As filler I ment clay around the figurine.
3. What you see on picture is demolded object flip around. I do exactly what you posted on picture Mold Making and Plaster Mixing 101
Well I will let you know if I figure it out. Maybe I do something stupid what I'm not realizing 
 
 

I’ve never done it personally, but I’ve seen tutorials about painting parts (or all) of the plaster mould with a layer of coloured slip and letting it set up a little before pouring the “main” casting slip. It allows you to just use a coloured version of the slipcasting body of your choice to decorate, and it’s thoroughly integrated into the piece. 

@PeterHPSH is on the other side of the country from the OP. A bit closer would be Plainsman, and they’ve listed 2.5 kg at $619.35. Kinda better?
Plainsman may or may not ship to BC, but I know Ceramics Canada in Calgary will, or they’ll put things aside for you if you’re visiting family in town. They usually sell at about the same price. Lots of folks from BC order from Alberta to avoid the sales tax.
Adding or removing lithium is probably going to mess with glaze fit. Other questions for later rounds of testing might include whether or not the changed LOI will affect an iron red. I don’t know what this particular tenmoku turns out like, but speckling effects might change. 

@PeterHfrom that same wiki, 
“A 1.0 M solution (about the concentration of domestic vinegar) …”
So if domestic vinegar is somewhere between 5 (regular white vinegar) and 7% (pickling vinegar) by volume,  then 3 M vinegar would be between 15 and 21%. Very unscientific calculation there, but perhaps close enough for these purposes.
In what I thought was a rather spectacular example of greenwashing, you can get Eco Living Solutions brand 25% industrial grade acetic acid on that South American River website. 45 and 75% also appeared to be available in different brands, I just thought the marketing on that one was hilarious. 

It might be worth trying excess hot vinegar first.
Mechanism and kinetics of wollastonite fibre dissolution in the aqueous solution of acetic acid
https://www.sciencedirect.com/science/article/abs/pii/S0032591010005267?via%3Dihub
The dissolution of fibrous wollastonite (CaSiO3) in the aqueous solution of acetic acid (3 mol dm− 3) was investigated in the temperature interval from 25 to 50 °C using mixed batch-type reactor.

I'm a bit uncertain, but I think that 3 mol dm− 3  is about 18% vinegar. The pickling vinegar I use for descaling my kettle is 6%, so it would be weaker than that used in the paper, but might still be strong enough to dissolve your crystals (if they are derived from Wollastonite).  Perhaps worth trying before you buy the HCl.
PS You might be wise to check my workings.
Molar mass of acetic acid ~60g  https://en.wikipedia.org/wiki/Acetic_acid
1dm = 10cm. 1 dm 3   = 1000ml = 1 litre
So 3 mol dm− 3  = 3*60g/l = 180g/1000g = 0.18 = 18%
 

It sounds like you have access to a kiln. Is there a problem with doing a ^018 firing? If the expense of the gold seems a problem, but you want to make several items, I think you will find that a little goes a long way. There is enough in a small bottle to do some preliminary tests before you commit to the final piece (s).
Gold luster is best used in small areas and, as in your example, on black or dark surfaces. 

As far as I can tell it is an extended Si:Al ratio showing the relationship of acid (silica) to base (RO and Al2O3). There is a lot of discussion on if you should have B2O3 as an acid or a base and some interesting experiments showing that you can trade Al2O3 for B2O3 as they are both sesquioxides (an oxide in which oxygen is present in the ratio of three atoms to two of another element)
Some argue that if B2O3 was an acid you should be able to reduce silica when adding boron but most times you need to increase silica when adding boron so how can it be seen as the same as SiO2. 
 
If anybody wants to get copies of the Transactions of the American Ceramic Society volumes you can find them here - https://archive.org/search?query=subject:"American Ceramic Society" All in the public domain so I assume I am fine sharing here as it's not for commercial use. 
 

Thinks for posting the kiln plate. I hope that the experts will chime in, but I suspect that the max temperature of 1300C means that the element life - when firing to your desired temperature -- is likely to be quite short.
For example see the first answer in
PS I'm not certain if the figure of 50 firings includes the lower-temperature bisque firings.

A few thoughts on your crystals
- As you cannot dissolve them in hot water this might indicate that they aren't boron-based.
- If you have dilute hydrochloric acid it will dissolve most calcium salts, including the silicate
... see A in http://www.pharmacopeia.cn/v29240/usp29nf24s0_m12120.html
If you find a way of reproducibly creating the crystals it might be interesting to try:
- Using a different deflocculant (Darvan?), which will probably change the pH of the slip which might change things.
- Seeing if a small addition of sugar to the fresh slip influences the growth of the crystals [*]
[*] Adding sugar would probably be very bad for the moulds, but just might form an interesting experiment. I mention it because sugar has a significant effect on the settling time of cement, apparently by its surface action on things like Wollastonite.
 


 

A bit more searching and I have found how they are calculating the oxygen ratio. Orton seems to say it is only useful in comparing similar glazes and they all seem unsure if you need to include B203.
 
I have no idea  what to do with it yet.

Just to mention the discussion of unwanted crystal growth in http://ceramicstoday.glazy.org/articles/flambe_magic.html
... it also makes me wonder if there could be a "pumping" action if the liquid is repeatedly warmed and cooled.

>If anyone is aware of a small quantity source for the darker, more deeply pyrolyzed starch sizing/adhesive called "British gum" please let me know. 
May be of relevance.

Pyrotechnics data for your hobby: Dextrin
https://pyrodata.com/chemicals/Dextrin
Sources:
Dextrin is easily prepared from starch. Potato and cornstarch will both work fine. The starch is spread out on a sheet in a layer about 1 cm thick and placed in the oven. The oven is then heated to 220°C(400°F) for several hours. The dextrin will turn slightly yellowish brown. One way to check if all the starch has been converted is to dissolve a small sample in boiling hot water and add a drop of KI3 solution (Lugol's iodine solution). A blue colour indicates presence of starch, which means the conversion hasn't completed yet. KI3 solution is conveniently prepared by dissolving a crystal of elemental iodine in a potassium iodide solution.

The complete removal of starch could be important in your application, so I would try the starch-iodine test.
PS
Dextrin and Making Dextrin
http://www.wichitabuggywhip.com/fireworks/dextrin.html
 

If you are trying different brushes &  handling techniques there is a Chinese calligraphy practice paper/cloth that you can draw on with a water filled brush. When wet it gives a dark image which slowly  fades as it dries. Often called magic-paper/cloth. Sometimes it has guide-lines for calligraphy, but plain sheets are also available.

PS another sort of specialised brush

Just eye candy:  glazes where slow cooling can have a dramatic effect.

From Super Cool! Slow Cooling in an Electric Kiln
https://ceramicartsnetwork.org/daily/article/Super-Cool-Slow-Cooling-in-an-Electric-Kiln

...and

The samples above remind me of fashion art. Simple line work using pen or brush to capture the essence  using gestures etc… If you google fashion artists you may find more samples and more inspiration. Folks who are good at it often capture things using pen and simple gestures very effectively with simplicity.

Some fashion Artists here : https://www.fashionillustrationgallery.com/artists
Andy Warhol definitely is in this list

No experience, but might that have been done with a ruling pen? Although these are often used to make very uniform "ruled" lines I believe that shifting the angle of use can produce varying line widths. This example seems to have a similar blotch-iness  in the thicker lines in your example.

Are You Using Your Ruling Pen to its Full Potential?
https://garnerwildlifeart.wordpress.com/2021/05/28/what-is-a-ruling-pen/

No experience, but might that have been done with a ruling pen? Although these are often used to make very uniform "ruled" lines I believe that shifting the angle of use can produce varying line widths. This example seems to have a similar blotch-iness  in the thicker lines in your example.

Are You Using Your Ruling Pen to its Full Potential?
https://garnerwildlifeart.wordpress.com/2021/05/28/what-is-a-ruling-pen/

Just eye candy:  glazes where slow cooling can have a dramatic effect.

From Super Cool! Slow Cooling in an Electric Kiln
https://ceramicartsnetwork.org/daily/article/Super-Cool-Slow-Cooling-in-an-Electric-Kiln

...and

Just eye candy:  glazes where slow cooling can have a dramatic effect.

From Super Cool! Slow Cooling in an Electric Kiln
https://ceramicartsnetwork.org/daily/article/Super-Cool-Slow-Cooling-in-an-Electric-Kiln

...and

There isn't a one size fits all type program for slow cooling. What works for one glaze won't necessarily give you the same results with another glazes. If the glaze is a high gloss one then slow cooling might not have any appreciable effect on it. If on the other hand it's one with fairly high amounts of one of the matting oxides (calcium, magnesium, alumina, strontium, barium, titanium or zinc) then slow cooling will more than likely have an effect. Getting the schedule is a bit of trial and error but a general starting place for a cone 6 glaze fire once it's reached it's top temperature could be 9999F to 1900F then ramping down at 150F an hour to 1400F then off.  (9999F is basically putting the kiln in a freefall without getting an error message)
If you do a drop and hold schedule for healing pinholes and blisters then I would suggest dropping your peak temperature at a rate of 9999F to 100F below your top temperature then holding there for approx 20 minutes then proceed with the 9999F to 1900F then 150F down to 1400F then off. 
If you find the glazes are too matte then increase the temperature it drops at (perhaps to 175F an hour) and/or raise the 1400F up and see how they turn out. If they are too glossy but might be matte with a slower cool (perhaps 125F and hour).
 

Might have been this one, where the choice of terminology seemed to be a hindrance rather than a help.
I'll freely admit that I'm not sure what temper means, and I'm pretty sure that it means different things to different people.
One meaning is:
Temper is non-plastic material that is added to clay to keep it from cracking when it dries. It is most often sand, ground stone or ground fired ceramics but historically a wide range of materials have been used for temper. 
e.g. see
Tempering Pottery Clay https://ancientpottery.how/tempering-pottery-clay/
Temper (pottery) https://en.wikipedia.org/wiki/Temper_(pottery)
Another meaning  relates to the non-pottery specific definition of tempered as
limited or controlled, or made less extreme https://dictionary.cambridge.org/dictionary/english/tempered
... and I expect that there are others.
OTOH you seem to want an additive to achieve a really smooth clay. So I don't think its currently  cracking, and you are trying to make its smoothness more extreme.  So I suppose I'm asking if something like "less gritty" or "more plastic" would capture your intentions better (and leave less room for misunderstandings).
PS What mesh-size is your final sieve?
Particle Size in How to Find and Test Your Own Native Clays
https://digitalfire.com/article/how+to+find+and+test+your+own+native+clays
But for fine functional ware, you will need a way to screen out +100 mesh sizes (see links below).

Might have been this one, where the choice of terminology seemed to be a hindrance rather than a help.
I'll freely admit that I'm not sure what temper means, and I'm pretty sure that it means different things to different people.
One meaning is:
Temper is non-plastic material that is added to clay to keep it from cracking when it dries. It is most often sand, ground stone or ground fired ceramics but historically a wide range of materials have been used for temper. 
e.g. see
Tempering Pottery Clay https://ancientpottery.how/tempering-pottery-clay/
Temper (pottery) https://en.wikipedia.org/wiki/Temper_(pottery)
Another meaning  relates to the non-pottery specific definition of tempered as
limited or controlled, or made less extreme https://dictionary.cambridge.org/dictionary/english/tempered
... and I expect that there are others.
OTOH you seem to want an additive to achieve a really smooth clay. So I don't think its currently  cracking, and you are trying to make its smoothness more extreme.  So I suppose I'm asking if something like "less gritty" or "more plastic" would capture your intentions better (and leave less room for misunderstandings).
PS What mesh-size is your final sieve?
Particle Size in How to Find and Test Your Own Native Clays
https://digitalfire.com/article/how+to+find+and+test+your+own+native+clays
But for fine functional ware, you will need a way to screen out +100 mesh sizes (see links below).

+1 for a fine mesh kyanite. @EarthToMatthew, good article on kyanite additions to clay below, worth a read to see if it sounds like what you are looking for.
https://digitalfire.com/material/kyanite