How Are Bonsai Pots Made? (The Complete Journey Of Clay Through The Production Process)

Bonsai pots are pretty important for the hobby of bonsai, but have you ever wondered how they are made?

Creating a ceramic bonsai pot is quite a long process and I will go through the main steps that are required to go from a lump of clay, all the way through to a finished pot that you can plant a tree into.

This will be general overview of the process, as you may find some potters do things slightly different, potentially adding or removing some steps, but in general this is how you make a ceramic bonsai pot. 

The Clay Is Selected

To get started with making a pot, you need some clay.

This really can be an important decision as the clay you choose can really affect things, such as the function, look, feel and just how you actually make the pot.

Different clays will of course be different colours, which will affect the final colour of the pot, but there is so much more to that that.

Different clays are going to have different strengths, heat resistances, workability and even how long you need to wait for them to dry as well as how they react to being fired.

Of course a lot of these clays are going to be priced differently and will also have different availability which all needs to be taken into consideration too.

Picking the right clay for a pot really has a lot more to it than just going for the first one a potter can get their hands on. 

The Clay Is Shaped Into A Pot

The first and maybe one of the biggest steps in the process is turning the lump of clay into the actual shape of the pot.

This may seem easy, but it is actually extremely difficult. This will either be done by hand, or in a mould. Usually the moulds will be used by factories so they can mass produce pots quickly.

When we think of creating a pot, this is usually the only part we think about, this is when a shapeless lump of clay gets turns into what looks like a finished pot, so it’s easy to overlook the rest of the steps.

I have written about this process in more detail, where I talk more about the different ways the clay can be shaped by hand or moulds,  which you can read here –  What Are The Different Ways Bonsai Pots Can Be Made ( Shaping Pots by Hand vs Factory Made)

The Pots Are Left To Dry

Once the pots have been shaped then are then left to dry. Usually the clay that is being used looks pretty firm and you might think this step is a total waste of time, but it’s extremely important.

The drying allows any water in the clay to escape, which is important as you do not want water trapped in the clay when it is fired. Trapped water will turn to steam in the hot kiln and it can crack the pot as its tries to escape from the clay.

Leaving the pots to dry out first is going to reduce the risk of cracking significantly.

The pots are usually left for a few days and even sometimes up to a week. You are probably never going to get 100% of the water out, but letting them dry out as much as possible does drastically help.

The Clay Pots Are Fired In A Kiln

Once the pots are bone dry they are then fired in a kiln, which is basically a super hot oven that transforms the soft clay into the solid clay.

This part of the process can vary greatly from potter to potter based on a number of different things such as what clay is being used and what the end goal is.

There is usually a heating phase followed by a final maximum temperature that is reached and then a cooling phase. What temperatures are used and how long these stages all last for can all be varied for different results.

When people think about pottery they assume the real skill is in shaping the clay …which it is …but there is also a real skill in understanding how to fire the clay to get the best results.

If you get this part wrong the clay may crack or end up being brittle, which basically means it is useless, so it is extremely important that you get the whole firing process right.

The firing process can also influence how frost proof a pot is, usually the hotter the kiln, the less porous the final pot will be. A less porous pot is less likely to absorb water, which can expand inside the pot when it is frozen, causing the pot to crack.

Electric or Wood Fired Kiln

Traditionally kilns would have been fuelled by wood fires, but now they are usually electric.

You might think they are the same I guess you can compare it to using an electric oven, or cooking on a barbecue …both will cook your dinner, but you will get a very different result.

The electric kiln is going to give you very consent results as well as being easier to manage and run. The wood fired kiln is going to take a lot more effort and skill to operate and you can also produce some very interesting results, especially with glazes.

Which one is used is going to depend on the individual potter and what they have access to, or prefer to work with.    

Pots Are Usually Fired Twice

You will find that it is very common for bonsai pots to be fired twice. The first firing is usually at a lower temperature and this is often called “bisque firing” this changes the clay into a harder form, but it still remains quite porous.

The second firing is usually hotter and this is when the glazed is applied.

Pots Can Now Be Glazed

After the pot has had its initial firing and has cooled, it can be glazed and re-fired.

Not all pots are glazed, but as I am sure you know, they are popular in the bonsai world. The glazes can be a pre-bought mix, or the potter can create their own.

There is also many different ways they can be applied to the pot. Every potter will probably do things slightly differently which is why we have so many different coloured pots

Why Are Bonsai Pots Not Glazed On The Inside?

You have probably noticed that in the inside of a bonsai pot is not glazed, this is for a few reasons, the first being that it would be pretty pointless. The pot is going to be full of soil …so you are not exactly going to be able to see it and enjoy it. It would be kind of a waste of glaze.

However, it is actually more beneficial to leave it unglazed. The clay can be quite porous and it can absorb some of the water from the soil. This can help stop the inside of the pot being so wet and it also means that when the soil dries out, the water can come back out of the walls and help moisten the soil.

This is generally better for the tree compared to using a plastic pot where the water excess water can get trapped in between the walls of the pot and the soil. I don’t think the problem is noticeable enough for us to worry about, but it does happen and the breathability of a ceramic pot is just generally better, even if it isn’t really that measurable.         

Plastic Pots Are Made Differently

When it comes to plastic pots, the process is pretty different. Although, I guess there are some similarities. The manufacturer has to pick what type of plastic they use, as these can have different properties, as well as the colour they want, but I think their spectrum of choices is a little more limited compared to clay. 

Plastic pots are then formed in moulds, which is how they are the all exact same. The process will usually be done by machines and once they come out of the moulds they are pretty much ready. They don’t need fired in a kiln and they wont have any glaze added.

Conclusion

As you can see the journey from a lump of clay to a final bonsai pot does require quite a few steps.

Each step requires a lot of time and skill to get things right, so you can probably now see why some pots are quite expensive, however, the craftsmanship that goes into them is certainly worth paying for.

(You can read more about – What Shape Bonsai Pots Can You Get?)