How it's made

[VladCruceanu]

How is this kind of wall made with hand building techniques?  Straight walls are easy to build and join with 45 degrees cut. Being curved at the end is making me very curious. 

Sometimes I see bonsai pots that are don t have vertical walls but again, curved walls. 

[VladCruceanu]

Same with this add on in the middle of the wall. Is it carved or added? If it's added on the wall, how can I obtain a straight, very thin form?

[neilestrick]

It's probably slip cast from a mold.

[Magnolia Mud Research]

2 hours ago, neilestrick said:

It's probably slip cast from a mold.

Or produced in a press mold.  

LT

[shawnhar]

Those have to be hollow right? No way I could have walls that thick survive firing, lol

That add on frame thingy would be super easy to add, just roll a thin slab on paper and cut that out with a straight edge and stick it to the pot. (I say super easy but it would be a pita keeping the lines straight when applying)

Curved walls are not hard to do with slab built boxes, you just cut arcs instead of 90 degree straight lines, but keeping everything uniform  and straight is super hard without a mold. If I were going to try and reproduce that I would have to have a mold, I'm pretty new though and in my 1st hand building class.

[Rae Reich]

I believe these are slip cast from one-part molds. The feet and side decorations are cast separately and added on, as well as the lugs inside for securing bansai roots. The rims are thick for sturdiness, but the walls, if you look closely, are thinner. Examining one in person would be instructive.

For production of multiples, I would hand build my desired original bansai planter shape, sculpting detail with no undercuts. Cast the form in plaster so that it will be  filled from the top with slip. 

Or just hand-build single originals to suit your fancy without regard for slip casting requirements. 

[Chilly]

On 11/19/2018 at 12:25 PM, VladCruceanu said:

How is this kind of wall made with hand building techniques?  Straight walls are easy to build and join with 45 degrees cut. Being curved at the end is making me very curious. 

Sometimes I see bonsai pots that are don t have vertical walls but again, curved walls. 

 

Thick slabs to start, carved away, both inside and out.  Possibly clay added to round out.  Similar to making a sculpture, start with a lot of clay, then remove what is in the wrong place, and add more where needed.  Try to aim for an even thickness.

 

On 11/19/2018 at 12:26 PM, VladCruceanu said:

Same with this add on in the middle of the wall. Is it carved or added? If it's added on the wall, how can I obtain a straight, very thin form?

 

This could be pushed out while the clay was still soft.

 

Like others have said, these are highly likely slip-cast.  I don't think it would be easy to make from slabs, but not impossible either.  I have made a slba-built one similar to the first one, but slightly less curved.  For a one-off, something to fill your time, they are doable.  For wanting to make and sell lots, make a solid one, with the outside as you want, and then make a mould.

Good luck

[Fred Sweet]

Vlad-

Once you have a mold, you can use it as a press mold. If you do use it as a press mold you can “customize” each one after you drop them out. Doing this can keep you involved with the basic form and slow down the inevitable “burn out”, as well as being able to provide your customers with an ever-changing product.

Regards,

Fred

[Chilly]

39 minutes ago, Fred Sweet said:

Vlad-

Once you have a mold, you can use it as a press mold. If you do use it as a press mold you can “customize” each one after you drop them out. Doing this can keep you involved with the basic form and slow down the inevitable “burn out”, as well as being able to provide your customers with an ever-changing product.

Regards,

Fred

 

You can do the same with slip-cast if you make it thicker than required.  I've done this and then made new moulds from the altered originals.

[VladCruceanu]

I understand how the mold works when I have the object but I am in the situation where I have to create the object and after that build the mold. The first idea coming in my head is to use a 3D printer for the object and after make the mold. How are you doing it? 

Perfect straight walls can be made only when using a mold or I should improve my techniques? I am hand building from slabs and when I am creating a larger pot (40 cm x 20 cm) it seems impossible to keep everything 100% straight. For smaller pots is not hard. Even if the large pot seems straight during the building and finishing phases, at bone dry level is always deforming. I am slowly drying to bone dry, covering the whole object with a bag and putting it on a shelf. The room is heated from the ground level and there are no strong airs inside, it's a closed chamber.

[Chilly]

Make your model from solid clay, don't let it dry out. 

Cast your plaster mould when the clay is still moist, but firm enough to take the weight of the plaster. 

Or you could cast a solid lump of plaster and carve that into the shape of your model, then cast your mould from that. 

Your model could also be carved from wood.

[Min]

I would make the mold from a solid mass of clay like Chilly suggested. You would make it rim side down on a flat smooth surface, I would use a profile rib to get the sides uniform, make the mass bigger than the finished size and scrape it down with the profile rib and level the top of the clay (which will be the bottom of the pot). Cottle boards around the damp clay and plaster poured. Feet would be added after the pot is poured, the trim detail on the sides could be worked onto the form prior to casting it or added after the piece is poured.

Profile rib made from wood, cut the curve in the wood to the shape you want the sides. Like the metal one in the image below but leave a right angle at the base of it so the rib runs square along the flat surface you are forming it on. I made a series of molds like this years ago for a dinner set and used slabs of clay to make the plates and bowls.

 

[Mark C.]

Its made from a mold-I knew someone who is now deceased who made that exact same form of bonsai pot-slip cast from red clays.

The feet are added later to form.

[Magnolia Mud Research]

Why not use the 3-D printer to make the mould(s)?

LT

[Rae Reich]

On 11/23/2018 at 9:57 AM, Magnolia Mud Research said:

Why not use the 3-D printer to make the mould(s)?

LT

If one has access to one, it would be making a form that includes trim, so not castable. The printer would be needed for every pot. 

[Rae Reich]

On 11/23/2018 at 12:03 AM, VladCruceanu said:

I understand how the mold works when I have the object but I am in the situation where I have to create the object and after that build the mold. The first idea coming in my head is to use a 3D printer for the object and after make the mold. How are you doing it? 

Perfect straight walls can be made only when using a mold or I should improve my techniques? I am hand building from slabs and when I am creating a larger pot (40 cm x 20 cm) it seems impossible to keep everything 100% straight. For smaller pots is not hard. Even if the large pot seems straight during the building and finishing phases, at bone dry level is always deforming. I am slowly drying to bone dry, covering the whole object with a bag and putting it on a shelf. The room is heated from the ground level and there are no strong airs inside, it's a closed chamber.

To have straight walls, make your form inside a box or container with the desired dimensions. You might need to create your own from wood. 

Curved detail on the outside can be kept straight with a tool like Min suggests, used with a guide nailed or clamped in parallel to the form.

[VladCruceanu]

Many thanks all for the replies.

@Rae Reich Great ideas, cheers.

[VladCruceanu]

23 hours ago, Rae Reich said:

To have straight walls, make your form inside a box or container with the desired dimensions. You might need to create your own from wood. 

Curved detail on the outside can be kept straight with a tool like Min suggests, used with a guide nailed or clamped in parallel to the form.

Something like this you mean? How did the guy made that 2-3 parts box? What material is that?

 

 

[Rae Reich]

He is using a plaster mold which has 3 parts - a top and a 2 part bottom. Making plaster molds for ceramic forms is a skill you would need to learn if you want to make multiple pieces of your own original design.

You might be able to purchase a plaster bonsai mold to make basic forms, to which you can add your own design elements.

Or, you can make your bonsai without using a form or mold, with clay slabs as the maker above did for his other pieces. Using straight edges as guides can help you make symmetrical forms if that quality is essential to you. 

[Chilly]

13 hours ago, VladCruceanu said:

Something like this you mean? How did the guy made that 2-3 parts box? What material is that?

 

As Rae says, it's made from plaster. 

How is it made?  Hummmm. There are very few videos that show the whole process.  Google "plaster mould making", and you will find lots on making one-piece moulds, not much on two-piece, and almost nothing on three-or-more-piece moulds.

If you've not worked with multi-part moulds before, they can seem amazing.  They are in many parts so you can remove the finished item, which has undercuts.  If they were one piece, you would never get the finished piece out.

 

If you are going to go down this rabbit hole, I suggest you find a mould to purchase, so you can see how it works.

I find visualising how the mould should come apart the most difficult part.

I own a two-piece, commercially made bonsai mould,.  The top part was broken, so we stuck some plywood to it to hold it together.

With this mould, like the one in the video, the top is to give a smooth finish to the rim.

Like here

 

[VladCruceanu]

7 hours ago, Chilly said:

As Rae says, it's made from plaster. 

How is it made?  Hummmm. There are very few videos that show the whole process.  Google "plaster mould making", and you will find lots on making one-piece moulds, not much on two-piece, and almost nothing on three-or-more-piece moulds.

If you've not worked with multi-part moulds before, they can seem amazing.  They are in many parts so you can remove the finished item, which has undercuts.  If they were one piece, you would never get the finished piece out.

 

If you are going to go down this rabbit hole, I suggest you find a mould to purchase, so you can see how it works.

I find visualising how the mould should come apart the most difficult part.

I own a two-piece, commercially made bonsai mould,.  The top part was broken, so we stuck some plywood to it to hold it together.

With this mould, like the one in the video, the top is to give a smooth finish to the rim.

Like here

 

Where did you bought the bonsai pot mould from?

Thank you all for your help.

[Chilly]

The mould came from someone who had hundreds.  I only got it because it was broken.