Jeff Longtin

A couple thoughts: would it be possible to inflate the toy using water? Potentially you could freeze it , after its filled, to make it solid.
You mention foam insulation...have you tried the foam tire inflation kits that bicyclists use? I'm told they work really well to keep a tire inflated.
Another alternative could be latex rubber.  It would flex with the form but you could apply several layers to develop strength.  
An extreme thought would be to put the inflated form into a box and then fill the box with alginate.  Once set you would gently cut the alginate and remove the toy and then fill the alginate mold with plaster.

Will keep my eye out for some and give it a go. I can see this working really well for large flat surfaces.

HERE is a good PVC size chart. Different types of pipe are measured differently- some by ID some by OD. They all come in various thicknesses as well.

Welcome to the Forum Johnny. What you have is a slip casting tank/pouring table. The parts are very simple mechanical parts. You may be able to find replacements at a Home Depot type store.  The motors are standard Dayton motors available through Graingers. (The tank/table itself is fairly unique and not easy to find a replacement for it.) 
To what degree you clean them, and use them, or buy new, is up to you. The market for tank/pouring tables is mostly a thing of the past. As a result they are much more expensive than they used to be. Cleaning what you have, and seeing how well it works, would be a good first step. 
When I first started casting, in the 80's, I was strongly encouraged to buy a casting/pouring table. I thought the design seemed logical enough so I was excited to cast up 1000's of pots. I soon found the design not so ideal. As I filled the table with molds at some point I chipped a few and plaster chunks fell into the slip.  That was annoying. Then I found that the little bits of hard clay that were left over, after draining the molds, would fall into the slip tank and need to be screened out. (as with the plaster.) I found that time consuming and inefficient.
In the end I found it easier to pour the slip into the slip tank and drain the mold away from the tank. Once the initial amount of slip is emptied out the mold is set aside and the remaining drainage is simply discarded. (In case plaster chips, and other stuff, contaminate it.)
Good Luck

Yes, Rae. I usually lay the grids on top of 1"x1" or 2"x4" strips for that reason. Especially fresh plaster.  For porcelain platters I find it's not necessary to provide that much circulation. Simply putting the grids on plywood bats works well in that situation.

As its comes up in the past, on occasion, I will mention a tool I use in the studio that is quite helpful.
Plastic grid light diffusers.
When I first started making molds I was surprised to find that freshly poured plaster emits a lot of moisture as it drys. My first attempts to provide a flat drying surface, 3/4" plywood, resulted in complete disasters. (As the plaster dried it dampened the wood. As a result the wood warped. As the wood warped so did the plaster. Completely ruined the plaster forms I was making at the time.)
A few days later, while at my day job, (maintaining a 26 story building) I replaced some overhead light diffusers in the freight elevator. Noticing that they were rigid I took them into the studio and tested them as drying surfaces. 
They're perfect. They're stiff so they don't warp. And they're plastic so they don't absorb any moisture from plaster or clay forms. The ones that work best are made of square grids that have hollow spaces in middle.
Down side is that they have little burrs, every so often, so one needs to be careful when drying clay pots on them. 
 
 

As its comes up in the past, on occasion, I will mention a tool I use in the studio that is quite helpful.
Plastic grid light diffusers.
When I first started making molds I was surprised to find that freshly poured plaster emits a lot of moisture as it drys. My first attempts to provide a flat drying surface, 3/4" plywood, resulted in complete disasters. (As the plaster dried it dampened the wood. As a result the wood warped. As the wood warped so did the plaster. Completely ruined the plaster forms I was making at the time.)
A few days later, while at my day job, (maintaining a 26 story building) I replaced some overhead light diffusers in the freight elevator. Noticing that they were rigid I took them into the studio and tested them as drying surfaces. 
They're perfect. They're stiff so they don't warp. And they're plastic so they don't absorb any moisture from plaster or clay forms. The ones that work best are made of square grids that have hollow spaces in middle.
Down side is that they have little burrs, every so often, so one needs to be careful when drying clay pots on them. 
 
 

Welcome to the Forum Johnny. What you have is a slip casting tank/pouring table. The parts are very simple mechanical parts. You may be able to find replacements at a Home Depot type store.  The motors are standard Dayton motors available through Graingers. (The tank/table itself is fairly unique and not easy to find a replacement for it.) 
To what degree you clean them, and use them, or buy new, is up to you. The market for tank/pouring tables is mostly a thing of the past. As a result they are much more expensive than they used to be. Cleaning what you have, and seeing how well it works, would be a good first step. 
When I first started casting, in the 80's, I was strongly encouraged to buy a casting/pouring table. I thought the design seemed logical enough so I was excited to cast up 1000's of pots. I soon found the design not so ideal. As I filled the table with molds at some point I chipped a few and plaster chunks fell into the slip.  That was annoying. Then I found that the little bits of hard clay that were left over, after draining the molds, would fall into the slip tank and need to be screened out. (as with the plaster.) I found that time consuming and inefficient.
In the end I found it easier to pour the slip into the slip tank and drain the mold away from the tank. Once the initial amount of slip is emptied out the mold is set aside and the remaining drainage is simply discarded. (In case plaster chips, and other stuff, contaminate it.)
Good Luck

My hunch is that there is too much sand in the clay.  I would have suggested you test the clay first before adding that much sand. 
Has the sand been washed? I've never worked with sea sand but I wonder if it adds salt to the clay? Do you know the mesh size of the sand? A smaller mesh would have less impact on plasticity. 
 

My hunch is that there is too much sand in the clay.  I would have suggested you test the clay first before adding that much sand. 
Has the sand been washed? I've never worked with sea sand but I wonder if it adds salt to the clay? Do you know the mesh size of the sand? A smaller mesh would have less impact on plasticity. 
 

My hunch is that there is too much sand in the clay.  I would have suggested you test the clay first before adding that much sand. 
Has the sand been washed? I've never worked with sea sand but I wonder if it adds salt to the clay? Do you know the mesh size of the sand? A smaller mesh would have less impact on plasticity. 
 

My hunch is that there is too much sand in the clay.  I would have suggested you test the clay first before adding that much sand. 
Has the sand been washed? I've never worked with sea sand but I wonder if it adds salt to the clay? Do you know the mesh size of the sand? A smaller mesh would have less impact on plasticity. 
 

To answer both questions:
M.A. Handpainted - Unless the bisque has been in a nice box and well wrapped I would suggest you wash it, and let it dry, before you paint it/glaze it. A fine dust can accumulate and spoil any surface decoration you apply.
LeeU - Years ago I made molds for all kinds of folks wanting to make all kinds of things. A few of these folks were the "paint on bisque" crowd. Coming from a potters background it puzzled me at first but then I realized it made sense.  If the piece isn't going to serve a functional purpose, and will be strictly decorative, why go through the bother of high fire. If bisque temp produces an item that will be permanent, without the higher temp firing costs, it makes sense to stay within the bisque range. Sure, a higher temp would make it more durable, but this was not a crowd that was looking for  generational durability. They just wanted a decorative piece to put in their house.  
On the flip side, I did make a mold of a classic Belleek porcelain vase.  It was the most delicate thing I've ever held and it had a crack. I reproduced it in modern porcelain and the customer was very pleased. Upon delivery she told me the vase had been in the family over 100 years.  
I met all types making molds and it was an eye opening experience.

To answer both questions:
M.A. Handpainted - Unless the bisque has been in a nice box and well wrapped I would suggest you wash it, and let it dry, before you paint it/glaze it. A fine dust can accumulate and spoil any surface decoration you apply.
LeeU - Years ago I made molds for all kinds of folks wanting to make all kinds of things. A few of these folks were the "paint on bisque" crowd. Coming from a potters background it puzzled me at first but then I realized it made sense.  If the piece isn't going to serve a functional purpose, and will be strictly decorative, why go through the bother of high fire. If bisque temp produces an item that will be permanent, without the higher temp firing costs, it makes sense to stay within the bisque range. Sure, a higher temp would make it more durable, but this was not a crowd that was looking for  generational durability. They just wanted a decorative piece to put in their house.  
On the flip side, I did make a mold of a classic Belleek porcelain vase.  It was the most delicate thing I've ever held and it had a crack. I reproduced it in modern porcelain and the customer was very pleased. Upon delivery she told me the vase had been in the family over 100 years.  
I met all types making molds and it was an eye opening experience.

To answer both questions:
M.A. Handpainted - Unless the bisque has been in a nice box and well wrapped I would suggest you wash it, and let it dry, before you paint it/glaze it. A fine dust can accumulate and spoil any surface decoration you apply.
LeeU - Years ago I made molds for all kinds of folks wanting to make all kinds of things. A few of these folks were the "paint on bisque" crowd. Coming from a potters background it puzzled me at first but then I realized it made sense.  If the piece isn't going to serve a functional purpose, and will be strictly decorative, why go through the bother of high fire. If bisque temp produces an item that will be permanent, without the higher temp firing costs, it makes sense to stay within the bisque range. Sure, a higher temp would make it more durable, but this was not a crowd that was looking for  generational durability. They just wanted a decorative piece to put in their house.  
On the flip side, I did make a mold of a classic Belleek porcelain vase.  It was the most delicate thing I've ever held and it had a crack. I reproduced it in modern porcelain and the customer was very pleased. Upon delivery she told me the vase had been in the family over 100 years.  
I met all types making molds and it was an eye opening experience.

I've been casting cone 6 porcelain, for years, and never had a problem with underglaze and seams/handles. 
As I cast thin I prefer to apply underglaze, Amaco, when the pot is bone dry.

Just to give you a heads up Lucy, if I'm perceiving the image correctly, it would appear you have a 1227. The "12" referring to the number of bricks running around the kiln. Just do a quick count before you buy elements.  An element for a 1227 will be different than an element for a 1027.
I can't recall if a 1227 has fuses but if it does those would be a simple fix. (50 amp fuses are about the thickness of your index finger and 2" long.) When an entire section is black its either a relay or a fuse.
 
 

To pick up on what the Pres mentioned...my gut tells me the slab is being overworked. (In the making process.) Too many "walls" are being attached and its causing stress in the firing. The walls may be necessary for strength and to hide things, but the attachment process is too stressful. Can I presume the slab is flat on a surface and you're pressing the walls into it? The question would be how can you reduce the stress when going thru this process?
My gut tells me you should create a form that is intact on its own, essentially, and then put the shaped slab OVER it. That way taking stress off the slab itself.

To pick up on what the Pres mentioned...my gut tells me the slab is being overworked. (In the making process.) Too many "walls" are being attached and its causing stress in the firing. The walls may be necessary for strength and to hide things, but the attachment process is too stressful. Can I presume the slab is flat on a surface and you're pressing the walls into it? The question would be how can you reduce the stress when going thru this process?
My gut tells me you should create a form that is intact on its own, essentially, and then put the shaped slab OVER it. That way taking stress off the slab itself.

To pick up on what the Pres mentioned...my gut tells me the slab is being overworked. (In the making process.) Too many "walls" are being attached and its causing stress in the firing. The walls may be necessary for strength and to hide things, but the attachment process is too stressful. Can I presume the slab is flat on a surface and you're pressing the walls into it? The question would be how can you reduce the stress when going thru this process?
My gut tells me you should create a form that is intact on its own, essentially, and then put the shaped slab OVER it. That way taking stress off the slab itself.

To pick up on what the Pres mentioned...my gut tells me the slab is being overworked. (In the making process.) Too many "walls" are being attached and its causing stress in the firing. The walls may be necessary for strength and to hide things, but the attachment process is too stressful. Can I presume the slab is flat on a surface and you're pressing the walls into it? The question would be how can you reduce the stress when going thru this process?
My gut tells me you should create a form that is intact on its own, essentially, and then put the shaped slab OVER it. That way taking stress off the slab itself.

To pick up on what the Pres mentioned...my gut tells me the slab is being overworked. (In the making process.) Too many "walls" are being attached and its causing stress in the firing. The walls may be necessary for strength and to hide things, but the attachment process is too stressful. Can I presume the slab is flat on a surface and you're pressing the walls into it? The question would be how can you reduce the stress when going thru this process?
My gut tells me you should create a form that is intact on its own, essentially, and then put the shaped slab OVER it. That way taking stress off the slab itself.

Good Morning Christy Ann. I have years of experience with MN Clay. 
When you mention Minnesota Clay 03 are you referring to Minnesota Clay #3 White Stoneware? It's been a very popular white stoneware for many years. 
Are you using the clay right out of the bag or is it reclaimed clay? Sometimes reclaimed clay can have bits and pieces that bloat in the glaze firing.
I use Amaco underglazes and regularely fire them to cone 6.  I use a cone 6 clear glaze over them.  Is your glaze a cone 6 glaze? Do the bubbles appear to be clear, i.e. glaze like, or does appear that the actual clay piece has bloated/bubbled?
 

Mold Design decision - While you can make a multiple part mold for a complex form you need to also consider the usability of such a mold. Each part creates a seam.(That needs to be cleaned.) Each part needs to fit together, well, with its neighbor, so the mold holds together tightly.
If you have a mold with lots of small parts you then have to be really careful when you work with the mold. If you crack, chip, or break just one part does it ruin the whole mold?
For the aforementioned reasons it is best, if possible, to keep your parts to a minimum. (Less time spent cleaning, less worry about breakage.)
Undercuts - A way you can keep detail but reduce its impact is to design the undercuts so they face one direction, either front or back. If you alter the undercuts so they follow the "pull" of the mold, as you separate the two pieces, then you can keep detail but make it work for you and not against you.
Hope this helps.

Great story Mark. 
Coincidentally I brought in a copy of "Clay and Glazes  for the Potter", by Daniel Rhodes, this morning, to introduce a younger employee to the types of books I referenced in my younger days. I asked her if she was familiar with "Alfred" as being the center of the universe, in the pottery world, for many years. She nodded that she heard of it but wasn't familiar with  it beyond that.
It certainly had an impact, on this young potter, from afar.