Chilly

Depending on any Internet restrictions in Malawi this might work, it’s how I read the book:
https://archive.org/details/pioneerpottery00card
 
l’m in over my head if I start talking what type of glass, what proportions, and the procedure for such a glaze. Stoneware potters of the southeast USA  were well know to use this type of glaze  a couple hundred years ago. 

You need a book that is written for UK available materials.  John Britt is fine in principle, but contains stuff we can't get.
The book you need to look for is Glazes Cone 6 by Michael Bailey.  (A quick google didn't find any for sale at a sensible price, but they do come up occasionally.  I bought mine 5 years ago, second-hand but brand new.)  

Potters have their own kind of white powder problems. 

I think that Tony Hansen's demonstration of the fallibility of ChatGPT is worth posting.
ChatGPT is completely wrong about the cause of glaze crazing!
https://digitalfire.com/picture/3159
... a fine example of ignoring the elephant in the room.
... a fine example of ignoring the elephant in the room by ChatGPT
PS It reminded me of a very old software engineering joke (1970s?).
A man was been taken on a cross-country flight in a helicopter. During the flight the ground became completely covered in dense fog, and the pilot became lost. The eventually came across the top of a office tower sticking above the fog, and they hovered nearby. The man attracted the attention of somebody in the office and held up a placard saying "where are we?", and received the answer "in a helicopter hovering 60ft above the ground".

The pilot said "OK I know exactly where we are, and set off towards their destination.
Later he explained "the answer you got was technically correct and not the slightest help, so obviously we were at the Microsoft help centre whose location I know".
Maybe ChatGPT is another help centre.

Separate the two processes: 1) filling the seams/gaps, and 2) filling the mold.
1) pour a small amount of slip into the mold and use a brush to push the slip into the seams/gaps. Wait a minute or two. Use the brush a second time to push the slip into the seam/gaps. Wait another minute or two. Do the same thing a third time if necessary. Wait another minute or two.
After you see the seam/gaps sufficiently filled THEN go ahead and start filling the mold. Go slowly to make sure your gaps are filled and no slip is leaking out. 
If it looks like you filled the gaps sit back and breathe a sigh of relief.
Right now my purse vase molds are just plaster parts held together with straps and rubber bands. The shape, 8" wide, 8" tall, 3" deep, is really susceptible to blowout if I forget to seal the seams. The above method assures that the slips stays in place and I get a decent casting without a lot of mess or stress.
 
 

As I find pictures helpful in forming memories, not a dissimilar 2-stage process to that in
Inlaid Slip Casting
https://ceramicartsnetwork.org/pottery-making-illustrated/pottery-making-illustrated-article/Inlaid-Slip-Casting

The only thing I would add, is if you want a defined line between different colours of underglaze AND are going to brush on the clear glaze, we have better results with  firing before brushing on the glaze.

I see!! (As I say, I am very new and am still trying to learn about clay properties, language ect! So that’s really useful). I think I was under the impression that firing to eathernware, being a slightly higher temp would make the piece more durable and less prone to breakage than if it was left at bisque! That is useful to know that I should be looking at the range of temperature my clay should be fired at to help gauge. 
Thanks. 

Thank you Chilly, that’s helpful:) 

I think you've got it.
Horizontal cracks within the glaze (acting as reflectors) would affect the colour (by reducing the distance light travels in the glaze) even if the colour is uniformly distributed in the glaze.
The small amounts of colourants in copper-reds might also be significant.
Snowflake Crackle https://ceramicartsnetwork.org/ceramic-recipes/recipe/Snowflake-Crackle
Color
The first thing I noticed when I did color tests with the usual colorants and opacifiers (copper carbonate, red iron oxide, chrome oxide, stains, Zircopax Plus, etc.) was that, as the color improved, the crazing ceased. This was because all oxides have expansion/contraction rates and adding them changed the CTE of the glaze enough to stop the crackle effect. I ran more tests with very low levels of colorants (under 1%), which kept the crazing yet still produced a nice color.
PS Do you have any similarly fired pots which  didn't show this effect? An ice-water stress test might be interesting.
PPS I wanted to suggest that the relative freedom from cracks near the edge of the bowl was a significant clue, but couldn't word it right.
So here is a picture of the effected -- with a smaller crackle size and hence smaller outside ring.
I've been testing a Snowflake crackle glaze. Here it is over coloured slip
https://www.reddit.com/r/Pottery/comments/8jjxxi/ive_been_testing_a_snowflake_crackle_glaze_here/

The only thing I would add, is if you want a defined line between different colours of underglaze AND are going to brush on the clear glaze, we have better results with  firing before brushing on the glaze.

Big plan for this summer is to get my partner fit and well and back out doing stuff after 18  months of surgery/partial recovery/surgery/partial recovery/surgery.
I'm going for a week's "summer school" with the Guild of Weavers, Spinners and Dyers - There will be with 300 people spread over 18 different courses.  I will be dyeing with natural dyes.  We will be staying at an agricultural university in Shropshire.
The rest will be filled with hiding from the sun - sun rash is really irriting - in all senses, gardening, spinning, weaving, dyeing and volunteering.  Oh, and some pottery.

When I make a plaster form it usually takes 5-7 days before its completely dry. I place plaster forms on plastic grates that allow air to freely flow around the object. If I forget to prop the piece properly and leave it on a wood board, or plastic sheet, it will develop a brown/green mold where it was in contact with the wood or plastic.
"Brushing off" - unfortunately this is subjective. When you pick up a plaster mold/form you will usually have some white powder on your hands/fingers. An indication that the plaster form is deteriorating would include an increasing roughness to the plaster surface.
 

My thoughts after reading that you can get the product on the Big river website.
Great to read that there is so much love and caring in our Community. 
 

@CharliesMomma, since you now know what was used another option would be to purchase another kit and make some test pieces with it.(just use something from around your house to make some little pieces with creases, maybe wrap them with saran wrap to get the creases) Wrap them up and leave them in tissue and see if they develop the same discolouration. If they do then finish drying them in the same way as your original pieces. Test those pieces with a quality plaster mildew/mold remover and leave them alone for as long as possible ( a year at least) then check for deterioration of those pieces. I would also contact a plaster restoration company if there is one near you and ask them about this, have them test the sample pieces.

Until you hear back from them I would put them in an area with lots of air circulation to help dry them completely.

This is such a good thing to do.  My usual saying is "It won't come out of the kiln any smoother than it goes in". 
You could also try gently wiping with a barely damp sponge.

When I've used Murphy's soap I used a quite damp sponge and applied on a thin layer. I let that dry then repeat with a bit of light buffing between coats. Keep adding coats until water beads off the surface. I then bought some mold soap, for me it works better. (I used Murphy's on a whole fish once, as the plaster heated up it made a nasty smell of hot stinky fish combined with Murphy's, Can't use the stuff now without gagging a bit, probably too much info)

This is such a good thing to do.  My usual saying is "It won't come out of the kiln any smoother than it goes in". 
You could also try gently wiping with a barely damp sponge.

Big plan for this summer is to get my partner fit and well and back out doing stuff after 18  months of surgery/partial recovery/surgery/partial recovery/surgery.
I'm going for a week's "summer school" with the Guild of Weavers, Spinners and Dyers - There will be with 300 people spread over 18 different courses.  I will be dyeing with natural dyes.  We will be staying at an agricultural university in Shropshire.
The rest will be filled with hiding from the sun - sun rash is really irriting - in all senses, gardening, spinning, weaving, dyeing and volunteering.  Oh, and some pottery.

Big plan for this summer is to get my partner fit and well and back out doing stuff after 18  months of surgery/partial recovery/surgery/partial recovery/surgery.
I'm going for a week's "summer school" with the Guild of Weavers, Spinners and Dyers - There will be with 300 people spread over 18 different courses.  I will be dyeing with natural dyes.  We will be staying at an agricultural university in Shropshire.
The rest will be filled with hiding from the sun - sun rash is really irriting - in all senses, gardening, spinning, weaving, dyeing and volunteering.  Oh, and some pottery.

Big plan for this summer is to get my partner fit and well and back out doing stuff after 18  months of surgery/partial recovery/surgery/partial recovery/surgery.
I'm going for a week's "summer school" with the Guild of Weavers, Spinners and Dyers - There will be with 300 people spread over 18 different courses.  I will be dyeing with natural dyes.  We will be staying at an agricultural university in Shropshire.
The rest will be filled with hiding from the sun - sun rash is really irriting - in all senses, gardening, spinning, weaving, dyeing and volunteering.  Oh, and some pottery.

Processing 150 pounds of clay. Should keep me going a little while. I’ll probably do another batch before fall. 

Just an update and I do not wanna jinx anything but I did about 50 more mugs wedging each ball individually per @Min’s suggestion and another chunk wedging larger amounts but then doing my normal elongating wedged clay to wire off smaller balls. I then truly spent an insane amount of time compressing bottoms. No visible cracks on any of the individual wedged ones and a handful on the ones using my normal method but with intense amounts of compressing. Looks like this is just going to be part of the process with frost. Thanks for all the suggestions and hope that is the end of that.
I do want to add some compliments to frost as well. It is hands down the best looking glazed porcelain I have ever seen. I also love how even when fairly wet it holds it shape very well for handling. This is especially important for me as I do all attachments much sooner than leather hard so I never have to really worry about joint cracks. So I may have to spend more time on the wheel but handles etc are much more efficient for me now.
off to do some glaze fit adjustments now…

Aha! The clay body is a buff one, which means it’s both a thickness thing and a reaction with the iron in the clay. 
The simplified explanation is that whatever’s in honey flux, it behaves very much like a rutile blue glaze. The blue colour isn’t from a pigment, it’s from how light refracts back through the glaze and into your eyes. So thickness and the colour of the background the glaze is on will affect the end results. A thinner application and a lighter background will make this glaze look like it does on the Dover white clay example Lee posted above, and you can see what thickness did to your buff Anasazi. If you put this glaze on a red or black clay, you’d need only a very thin layer to get that same blue/white variegation effect that is on the chess piece in your last picture. 
If you want it to look like Lee‘s version, you’ll have to use a different clay, or apply a white slip/underglaze to your existing one. 
 
edited to add: given that the MSDS lists zinc in the materials, cooling time may be a factor as well. If the kiln pack was tighter on one firing than the other, that could also account for the difference. Zinc tends to allow glazes to stay more fluid for longer periods, giving them more time to either continue any chemical reactions or to just smooth out.